Last December, I had the privilege of attending State of the Map Latin America (SOTM LATAM) in Belém, Brazil. I want to first share my gratitude to the entire community. I may be biased because I am latina myself, but latinos sure know how to make one feel loved and welcomed. This was my first […]
Last December, I had the privilege of attending State of the Map Latin America (SOTM LATAM) in Belém, Brazil. I want to first share my gratitude to the entire community. I may be biased because I am latina myself, but latinos sure know how to make one feel loved and welcomed.
This was my first time at SOTM LATAM, and I was deeply inspired by the energy, passion, and dedication of the OpenStreetMap (OSM) community in this region. The event showcased an impressive array of presentations and workshops, from mapping remote areas of the Amazon to using innovative tools and techniques for open mapping. I am so grateful to everyone who shared their work and insights, broadening my understanding of the challenges and opportunities in Latin America.
As a Director of the OpenStreetMap Foundation (OSMF), I had the opportunity to present about the role of the OSMF, the purpose of the Board of Directors, and how we strive to support the global OSM community. Engaging directly with attendees highlighted how essential it is for the OSMF to maintain stronger connections with regional communities. I was surprised to learn that this was the first time an OSMF Board member had attended a SOTM LATAM. Representation matters, and I am committed to ensuring this is not the last time. Strengthening our communication channels with the LATAM community is vital, and I am eager to build more meaningful and consistent engagement.
Open Conversations with the Community
A key part of this experience was the opportunity to hear directly from participants. During the event, an open online collaborative document page was shared, allowing attendees to express their thoughts, feedback, and even grievances with the Board. Some of the valuable insights included:
Regional Representation on the Board: There were discussions around creating dedicated Board seats for representatives from different regions to ensure equitable representation, particularly for communities that may struggle to gain sufficient global votes.
Lack of Awareness of Working Groups: Many attendees expressed that they were unaware of the existence and functions of OSMF Working Groups. Promoting these groups and encouraging participation from Latin American communities could strengthen regional representation and collaboration.
First Formal Board Presence: For many, this was the first time they had the opportunity to hear directly from a Board member. The engagement was positively received, and it was clear that there is a desire for more consistent interaction between the OSMF and Latin American communities.
Recognizing Regional Entities: Some established and active communities in the region are not formally recognized as official OSM chapters. This can create challenges in accessing grants and participating in global events. Greater support from the OSMF could bridge this gap.
Building Strategic Partnerships: Participants highlighted the potential for OSMF to collaborate with independent media organizations in Latin America, especially within data journalism, indigenous journalism, and environmental reporting. Strengthening these connections could increase OSM visibility and promote responsible use of open geospatial data.
Funding for Training and Capacity Building: Accessing financial resources for training journalists and other community members on OSM tools was identified as a critical need. Expanding funding opportunities for local projects could accelerate mapping efforts and amplify the impact of OSM data.
Moving Forward
The feedback shared during SOTM LATAM was invaluable. Meaningful participation and representation of all regions are essential for the growth and success of OpenStreetMap. We need to be more engaged with this and all communities. If you have any suggestions our communication channels (1;2;3;4 ) are always open.
To everyone I had the pleasure of meeting, thank you for your warm welcome and for sharing your perspectives. If you have further questions, comments, or feedback about the event or the OSMF, please feel free to reach out. ¡Obrigada, SOTM LATAM!
SOTM LATAM 2025 I’d like to also share with you all that SOTM LATAM 2025 will be in Medellin, Colombia from September 4th-6th. This is a great opportunity for all to get to know this amazing OSM Community and learn about the inspiring work they are doing.
In 1973, Gunther W. Holtorf was assigned as the manager of Lufthansa in Indonesia.
From his first year working in Jakarta, many friends and visitors from abroad frequently asked him to act as their guide in the city. To assist his guests, despite having no formal background in cartography, he began sketching maps of Jakarta. His work proved useful and well-received, encouraging
In 1973, Gunther W. Holtorf was assigned as the manager of Lufthansa in Indonesia.
From his first year working in Jakarta, many friends and visitors from abroad frequently asked him to act as their guide in the city. To assist his guests, despite having no formal background in cartography, he began sketching maps of Jakarta. His work proved useful and well-received, encouraging him to create a more detailed and comprehensive map of the city.
To achieve this, he initially approached the Jakarta City Planning Office. Instead of obtaining the topographic maps he sought as a base, he only found outdated maps of the city. This situation led the local civil servants to encourage him to produce a new map.
Gunther accepted the challenge. Every weekend, he explored Jakarta, navigating its narrow alleys and streets by foot, bicycle, and car. In addition to his weekend excursions, he also dedicated time each morning from 6:00 to 9:00 before heading to his office.
Throughout his explorations, he experienced various encounters. On one occasion, while passing through Tanah Abang and Tanjung Priok, his car’s tires were punctured by nails deliberately scattered on the road by robbers, who then seized his bag and equipment.
However, he also received warm welcomes from local residents. He was frequently approached by people who recognized him, particularly those who spoke English or German. “Hey, aren’t you the foreigner who was here last year?” he recalled hearing from friendly locals.
Finally, in 1977, coinciding with Jakarta’s 450th anniversary, his first map was completed. The 40x40 cm map—referred to by Holtorf himself as a “children’s map”—was presented to Jakarta’s governor, Ali Sadikin. Lacking professional training in cartography—his background being in economics—Holtorf entrusted the actual cartographic production to Cartographia, a Budapest-based company in Hungary.
The map covered areas from Ancol to Jalan Gatot Subroto. Since Holtorf resided in Kemang, he included a small portion of that neighborhood as well. However, districts such as Pasar Minggu and Kalibata were omitted, as he humorously considered them to be “foreign territory.”
Despite its simplicity, Ali Sadikin welcomed the map enthusiastically, as no previous map had depicted Jakarta in such detail.
By 2001, Holtorf’s Jakarta map had reached its twelfth edition, covering a much larger area. The southern boundary extended to Puncak, the eastern to Karawang, and the western to Tangerang. Each time a new edition was released, Holtorf personally verified Jakarta’s ever-changing landscape, a process that often took months. His sources of information had also expanded, including data from the National Coordinating Agency for Surveys and Mapping (Bakosurtanal), the Ministry of Public Works, Jasa Marga, and property developers.
In der letzten Woche waren drei von uns – Amanda, Michael und Frederik – auf der FOSSGIS-Konferenz in Münster. (Die Geofabrik ist auch Sponsor der FOSSGIS-Konferenz.) Die Veranstaltung, die jedes Jahr interessante Vorträge und Gespräche rund um alles im Open-Source-GIS-Bereich bietet, hatte dieses Mal rund 750 Besucher:innen und fand in den denkmalgeschützten Räumen im Schloss […]
In der letzten Woche waren drei von uns – Amanda, Michael und Frederik – auf der FOSSGIS-Konferenz in Münster. (Die Geofabrik ist auch Sponsor der FOSSGIS-Konferenz.) Die Veranstaltung, die jedes Jahr interessante Vorträge und Gespräche rund um alles im Open-Source-GIS-Bereich bietet, hatte dieses Mal rund 750 Besucher:innen und fand in den denkmalgeschützten Räumen im Schloss statt.
Alle Vorträge wurden vom CCC-Videoteam aufgezeichnet und können auf https://media.ccc.de/c/fossgis2025 angesehen werden. Amanda hat über ihr Projekt WaterwayMap gesprochen; Michaels Thema war, wie man in Deutschland noch neue Mapping-Aufgaben findet, und Frederik hat einen neuen OSM-Datenabfragedienst namens Postpass vorgestellt.
Der FOSSGIS e.V. hat auf seiner Mitgliederversammlung beschlossen, dass er Unternehmen und andere Organisationen, die OpenStreetMap nutzen, als „Förderer“ gewinnen will, um mehr Planungssicherheit für seine OpenStreetMap-Aktivitäten zu erreichen. Die Geofabrik hat natürlich gleich ja gesagt – wir sind die ersten! Unterstützen auch Sie die wertvolle OSM-Arbeit des FOSSIGS e.V., indem Sie Förderer werden.
Hello, my name is Gray Forsyth and I am currently a geography student with a strong focus in GIS at the University of Colorado Denver. I was recently introduced to Open Street Map by my remote sensing professor and OSM board member, Diane Fritz. I am excited to begin contributing high quality work to OSM.
I am beginning my OSM journey with a passion project to overhaul OSM’s data in my hometown,
Hello, my name is Gray Forsyth and I am currently a geography student with a strong focus in GIS at the University of Colorado Denver. I was recently introduced to Open Street Map by my remote sensing professor and OSM board member, Diane Fritz. I am excited to begin contributing high quality work to OSM.
I am beginning my OSM journey with a passion project to overhaul OSM’s data in my hometown, Wilson Wyoming. I decided to start this project because when looking at Wilson on OSM it was immediately clear that there was a significant amount of missing data, many inaccuracies, and lots of low resolution/quality vector work. I am excited to work on this project because I am not only passionate about making detailed, visually appealing and accurate maps, I also think Wilson is the most beautiful place on Earth (may be biased) and I want to do its landscape justice in the best way I can.
As I have already started the project, let me summarize the work I have done so far:
I began familiarizing myself with the editor by going around Wilson and beginning to address glaring errors. This first sweep began by focusing on Owen Bircher Park, where the boundaries, structures, pathways, and misc features were either inaccurate or missing. I then moved south to the downtown area of Wilson where many of the businesses and surrounding features were missing, inaccurate, unidentified, etc… There is also some work I have done to improve the roads in central Wilson.
Once familiar with the editor, I decided that the next order of business was addressing the two most obvious shortcomings (to me) of the data in Wilson; missing and low quality water features, and an abundance of missing structures in downtown Wilson.
Water is a very prominent feature throughout Wilson and is something that could use proportional attention. The riparian environment, as well as a significant amount of irrigation ponds and ditches, is not only a defining feature of the natural landscape, but a strong influence on Wilson’s residential topology.
Water work began by changing Fish Creek’s classification from stream to river, mostly because the symbology for rivers on OSM better suited the true size of the creek. I then began improving the accuracy and quality of Fish Creek’s vector line from around 2 miles north of and then around a mile south of central Wilson. This was mostly an aesthetic choice to make the line smoother and better representative of this defining water Feature. Ongoing water work consists of filling in the significant amount of missing ponds, ditches, and streams in central Wilson.
The amount of missing structures, specifically houses in central Wilson is fairly large, and existing structure data is mostly all inaccurate in position and shape. (also unclassified) So far I have made considerable progress in the east side of downtown Wilson. I have been striving to most accurately represent structure footprints, and cross referencing other imagery and street view when needed. I have also been adding driveways.
I will give another update once I feel the water and missing structure problems have been thoroughly addressed. Thanks for reading and feel free to reach out to me at grayforsyth21@gmail.com for any reason :)
how to move the street name to the side of the street.
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with this file coloured+name_offset.mapcss projeto.softwarelivre.tec.br/s/4z2jzQSjkL5oPTW you can move the street name to the side of the street, making the street name visible for better mapping of street names.
In this video I teach you how to use this file that you have to download to your computer.
File Link colou
how to move the street name to the side of the street.
with this file coloured+name_offset.mapcss https://projeto.softwarelivre.tec.br/s/4z2jzQSjkL5oPTW you can move the street name to the side of the street, making the street name visible for better mapping of street names.
In this video I teach you how to use this file that you have to download to your computer.
Как и почти все, я включал геолокацию, не задумываясь, как это работает, но проблемы, возникшие на моем смартфоне вынудили меня углубиться в тему и написать статью, чтобы, в первую очередь, упорядочить собственные знания и во вторую, сэкономить ваше время при решении схожих задачь.
Статья написана любителем и не претендует ни на что. Если нашли о
Время чтения: 10 минут.
Введение
Как и почти все, я включал геолокацию, не задумываясь, как это работает, но проблемы, возникшие на моем смартфоне вынудили меня углубиться в тему и написать статью, чтобы, в первую очередь, упорядочить собственные знания и во вторую, сэкономить ваше время при решении схожих задачь.
Статья написана любителем и не претендует ни на что. Если нашли ошибки, укажите на них в комментариях.
Т.к. смартфон является единсвенным инструментом картографии для подавляющего числа мапперов вне дома, неработающая геолокация может стать катастрофой. Чтобы этого не произошло, нужно выполнить ряд простых действий, но сначала термины)
Немного терминологии:
1. GNSS - Global Navigation Satellite System
Глобальная навигационная спутниковая система. Именно ее большинсво людей называют ошибочно GPS. В мире есть несколько систем GNSS: ГЛОНАСС - Россия, Navstar GPS - США, Beidou - Китай, Galileo - Европа, IRNSS - Индия и другие.
Полное покрытие имеет только ГЛОНАСС, GPS и Beidou.
Все (или почти все) современные модули геолокации смартфонов используют несколько систем навигации одновременно. Как правило, это: GPS, GLONASS, Galileo, Beidou.
2. Альманах
вид данных, которые передаются спутником на землю. Содержит информацию об орбитах всех спутников. Эта информация хранится на смартфоне и позволяет спрогнозировать примерное местоположение спутника в течении времени. (Например: Дня)
Эта информация достаточно долго хранится, но на ее основе будет не точное определение геопозиции.
Альманах для GPS транслируются каждые 12,5 минут, ГЛОНАСС каждые 2,5 минуты. Албманах может потерять свою актуальногсть, если на смратфоне сбилось время или местоположение изменилось на 100-200-300 км.
3. Эфемерида
точное местоположение каждого спутника. Гораздо точнее альманаха, обновляется каждые 30 секунд, но акутальность данных всего 30 минут. На приктике: Отключили геолокацию на час, при включении, модуль геолокации сначала обратиться к альманаху, а затем уже к эфемериде, что увеличит время поиска точной позиции.
4. Холодный старт
запуск геолокации после длительного отключение. В этом случае, данные эфемериды и альманаха станут неактуальными и смартфону придется с нуля искать спутники. Без использования вспомогательный технологий, этот процесс может занять до 10-20 минут.
5. Теплый старт
Запуск геолокации, которая ранее использовалась (но не раньше 30 минут с последнего старта). В этом случае, данные альманаха будут актуальный, а эфемериды устареют.
6. Горячий старт
Запуск геолокации, которая работала менее 30 минут назад. Поиск местоположения будет почти мгновенной, так как данные альманаха и эфемериды актуальны.
7. Assisted GPS
A-GPS - технология, которая позволяет почти мгновенно определять геолокацию даже в зданиях. Оно обновляет данные о местоположении спутников не с самих спутников, а загружая данные из сети. Это позволяет почти мгновенно запустить геолокацию даже при холодном старте. Мне не встречался ни один современный смартфон, который бы не поддерживал A-GPS.
Думаю, этого достаточно для поверхностного понимания работы геолокации на смартфоне. Теперь о том, как улучшить скорость и точность ее определения.
Как улучшить геолокацию на смартфоне.
Я буду описывать действия на примере дегуглизированной прошивки E OS на android 14 , но предполагаю, что на других прошивках действия будут схожи.
1. Включаем A-GPS
Настройки - Местоположение - Использовать A-GPS.
Как говорилось выше, это позволит обновить по сети данные о местоположении спутников (Альманах), что в разы ускорит холодный старт.
2. Поиск сетей Wi-Fi и Bluetooth
Настройки - Местоположение - Сервисы геолокации - Поиск сетей Wi-Fi и поиск устройств Bluetooth - включить.
Они позволяют определять свое местоположение относительно других устройств. В описании указано, что функция работает даже при выключенном Wi-Fi и Bluetooth, на практике гораздо лучше, когда модули включены. В идеале, датчик геолокации, wi-fi и bluetooth работают вместе, чем увеличивают точность местоположения, но в крупных городах, где многоэтажки, всякие антены и прочее, сигнал спутника гораздо слабее, в помещении и вовсе почти не поределяется. В метсах, где сигнал GNSS глушат, wi-fi и bluetooth вовсе не заменимы.
3. Отключаем ограничение поиска Wi-Fi
Настройки - О телефоне - Номер сборки - Тап несколько раз, пока не разблокируется режим разработчика - Назад - Система - Для разработчиков - Ограничивать поиск сетей Wi-Fi - Отключить
Дело в том, что гугл в какой то момент ограничил поиск сетей до 4 раз в 2 минуты. Вроде, чтобы не расходовать заряд батареи, который при постоянном поиске сетей будет снижаться. Это надо иметь ввиду при походах за город, хотя на открытых местностях спутники достаточно быстро находятся и точно определяют местоположение, так что вне города определение wi-fi и bluetooth из пункта 2 можно отключить, а в городе всегда есть где подзарядиться, так что не вижу в этом особо проблемы.
4. Калибровка компаса
Напрямую с точностью местоположиения не связан, хотя прирост, в теории, возможен. Что явно станет лучше, это направление стрелки при навигации, котороая может смотреть не в сторону движения, при плохой калибровке. Так же, это поможет с проблемой напаправления фото, если вы занимаетесь сьемкой панорам.
Для проверки калибровки компаса, рекомендую скачать приложение с F-Droid (свободный аналог гугл плей): https://f-droid.org/ru/packages/com.bobek.compass/
Справа серху этого компаса будет датчик его калибровки (Треугольник, похожий гна знак сети). Рисуйте смартфоном восьмерку по горизонтальной плоскости, пока точность не станет максимальной. мне 5-7 восьмерок вполне хватает.
Обычно это действие не требуется, но если ваши задачи требуют повышенной точности, таких как панорамы, треки для отрисовки ОСМ, или мелкие обьекты, типа подъездов, лучше включить геолокацию и нарисовать в воздухе несколько восьмерок.
5. Проверьте точность даты и времени на смартфоне.
Спутник передает сигнал своего времени и местоположения. Телеофн сравнивает со своим и на основе этого строит геолокацию. Чем больше отличается время на смартфоне от фактического, тем больше будет погрешность определяемого навигатором местоположения относительно вашего фактического. Как то так. Андроид берет время с ntp серверов, мобильного оператора, сети и т.д., но почти в 100% случаев проблем с временем нет. В теории, они могут появится, если вы долго находились без сети и андроид пользовался своими внутренними часами, но этот вариант не вижу смысла рассматривать.
6. Проверить чехол.
Убедитесь, что на чехле вашего смартфона нет магнитов. (В идеале, чтобы чехол был не металлический). Они могут исказить ваше местоположение. Чаще всего, магниты встречаются на чехлах книжках.
Прочая информация
Для хорошей геолокации требуется минимум 4 спутника. У каждого есть свой радиус действия. Пересечение окружностей 3 спутников даст местоположение с погрешностью 10-20 метров. Четвертый спутник снизит погрешность до 2-3 метров
Телефон так же определяет геолокацию по сотовым вышкам и насколько мне известно, дополнительных действий от вас тут не требуется, все происходит автоматически, была бы связь
Многие знакомы с термином триангуляйция, однако когда речь идет о геопозиции, этот термин несвосем верен. Правильный: Трилатерация - Триангуляция - Основана на измерении углов, где для местоположения одной точки нужно знать как минимум две других. - Трилатерация - Основана на измерении расстояний, где для уточнение точки требуется как минимум три точки (в нашем случае: спутника) с известным местоположением.
На маркетплейсах продаются наклейки, которые улучшают качества сигнала. Я не нашел вменяемого обоснования работоспособности данного метода, поэтому решил не тратить на них денгьги.
Иногда достаточно просто перезагрузить смартфон, что перезагрузит и модель геолокации, что может сказаться на его работе.
Если совсем ничего не помогает, возможно, дело в самом модуле и надо нести смартфон на диагностику. Есть программы для теста работоспособности модуля геолокации, но я не пользовался, не подскажу.
Говорят, на некоторых смартфонах геолокация работает лушче, чем на других, рейтинг где то видел, но подбирать смартфон по качеству геолокации, на мой взгляд, неправильно.
З.Ы. Началось все с того, что у меня никак не работала геолокация в помещении, несмотря на включенный блютус и вифи. Стал углубляться, проблему решил, а с ней и проблему индор маппинга (Маппинг всяких ТЦ.)
How to map objects in Openstreetmap with Rapid Editor.
UmbraOSM (Brazilian OpenStreetMap Mappers Union) brings you another video tutorial, teaching you how to use the Rapid editor to map buildings and roads in OpenStreetMap. Check it out and improve your mapping skills!
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Rapid Editor rapideditor.org/
www.youtube.com/watch?v=SOIQnPCuAug&t=902s
video link on youtube
U
How to map objects in Openstreetmap with Rapid Editor.
UmbraOSM (Brazilian OpenStreetMap Mappers Union) brings you another video tutorial, teaching you how to use the Rapid editor to map buildings and roads in OpenStreetMap. Check it out and improve your mapping skills!
¡Ya la vereda La Esmeralda se encuentra totalmente mapeada!
Parte de la vereda ya estaba mapeada por las contribuciones realizadas en el mapedo de las veredas Cascajo Arriba y Cascajo Abajo. Sin embargo, entre el inicio del año, el trabajo, y algunas labores como Secretario de la Asociación de Cartografía Colaborativa de Colombia - AC3, no pude contribuir por un ti
Últimas contribuciones
¡Ya la vereda La Esmeralda se encuentra totalmente mapeada!
Parte de la vereda ya estaba mapeada por las contribuciones realizadas en el mapedo de las veredas Cascajo Arriba y Cascajo Abajo. Sin embargo, entre el inicio del año, el trabajo, y algunas labores como Secretario de la Asociación de Cartografía Colaborativa de Colombia - AC3, no pude contribuir por un tiempo.
Consideraciones
En una entrada de diario anterior propuse usar DAMN para gestionar las tareas de mapeo de las veredas. Aunque lo intenté, aún no me siento de todo familiarizado con la herramienta, entonces su implementación se continúa aplazando. El Taskin Manager de HOT seguirá siendo la herramienta por defecto.
Sostenibilidad
Sigue siendo cierta la necesidad de implementar mecanismos de mapeo más eficientes. Por el momento, se me ocurre solicitar los polígonos de las construcciones a la Subsecretaría de Catastro Multipropósito, que al haber realizado la actualización catastral del municipio en 2024, cuentan con cartografía actualizada que puede ser de mucha utilidad para el mapa.
Sin embargo, al tratarse de una importación masiva, esta se debe hacer de manera cuidadosa, y siguiendo el respectivo procedimiento, documentando el proceso en la Wiki, e informando a la comunidad.
Más sobre este proceso en el futuro.
Ya en una entrada anterior mostré una iniciativa para que más personas contribuyan al mapa, en el marco de la actividad del Open Data Day 2025 en la UdeA. Aún tengo pendiente realizar actividades similares en las Instituciones Educativas de Marinilla.
Para las Istituciones Educativas hay que hacer algo similar para solicitar información oficial sobre las Sedes, entonces aún no lo llevaré a cabo. También hay que tener presente que Doris Ruiz (dcruizr) hizo una importación masiva con las fuentes del DANE, por lo que es importante trabajar sobre lo que ya se ha avanzado.
Bastian Greshake Tzovaras recounted his experience of contributing to MapComplete software by adding a wayside shrines layer. These small roadside altars, dedicated to saints or folk deities, serve as places of prayer and remembrance. They range from simple enclosures to elaborate sites filled with offerings.
Using an old address book from 1910, Benjamin_K has mapped the hotels of Berlin in OpenHistoricalMap then analysed their spatial distribution.
While working on a custom web map style that displays walking and cycling route names, Andy Townsend discovered that some hiking route names function more as descriptions rather than actual names.
Andy Townsend shared a guide on using the JOSM validator to identify errors in OSM relations.
DoudouOSM observed that some OpenStreetMap contributors meticulously map individual farmland parcels, revealing agricultural patterns that reflect historical practices, local geography, and technological influences. These patterns, visible from satellite imagery, range from precise geometric layouts to intricate mosaic-like formations.
With Vietnam planning to cut its number of provinces in half as a cost-saving measure, Eugine Alvin Villar couldn’t help but note that this could become the next major mapping project for the Vietnamese OpenStreetMap community.
The Latin American and Caribbean Open Mapping Hub held► a workshop on OpenStreetMap and tools such as Mapillary, Organic Maps, and uMap for faculty members at Tecnológico de Monterrey, Mexico. At the end of the three-day workshop, social impact projects based on collaborative mapping were designed.
Imports
Mathias_ADAV outlined► the process of importing free-floating bike and e-scooter parking areas into OpenStreetMap, using open data released by the Métropole Européenne de Lille in July 2024.
Local chapter news
OpenStreetMap US has published its March 2025 newsletter. There is news of the State of the Map US and much more!
Events
The call for participation at the State of the Map 2025, set to take place in Manila, Philippines, from 3 to 5 October, is now open. The programme committee is inviting submissions for talks, workshops, and panels, offering participants a platform to share their work and engage with the global OpenStreetMap community.
Falcius tooted a report on the OpenStreetMap booth during the first day of Chemnitz Linux Days. The booth remained open on the second day, accompanied by a scheduled presentation► titled ‘OpenStreetMap is (Not) Just a Map’, which showcased a selection of thematic maps created using OpenStreetMap data, alongside entertaining anecdotes about the project.
OpenStreetMap Indonesia organised a mapping talk series titled ‘Improving Data Quality of Road Mapping’. The session featured M. Iqnaul Haq, Maps Ops Manager at GoTo Group, who discussed the crucial role of OpenStreetMap data in optimising route quality to enhance the operational efficiency of Gojek, an Indonesian technology company providing ride-hailing, food delivery, and logistics services.
The official lobster of the State of the Map US 2025 informed us that the poster session application deadline has been extended to Friday 18 April at 12:00pm EDT! Show your neat maps, personal projects, OSM research, and more.
Education
Raquel Dezidério Souto has written a short guide showing how to map trees in OpenStreetMap with MapComplete and visualise them in three different ways (with Panoramax, overpass turbo, or uMap). This guide will serve as support material for the field mapping activities that will take place as part of Green Open Data Day 2025 or for general instructions.
HeiGIT reported that Knoblauch et al. have published a paper that underscores the critical importance of integrating vector ecology and human behaviour into advanced disease modelling frameworks. A part of the GeoEPI project, the analysis integrates knowledge of Aedes mosquito biting behaviour with human movement patterns to significantly improve inferences about urban dengue dynamics.
Accurate road surface information is crucial for emergency response and route planning. But OpenStreetMap has comprehensive surface attributes for only 30–40% of the roads worldwide.
Using state-of-the-art GeoAI methods, HeiGIT has created an openly available worldwide dataset on road surface types. A new paper presented the methods behind the dataset.
Humanitarian OSM
Séverin Ménard tooted that OpenStreetMap France has launched a humanitarian mapping initiative to assess building damage in Mayotte, a French overseas department, following Cyclone Chido, a tropical cyclone that struck Southeast Africa in December 2024. Utilising post-disaster satellite imagery from Copernicus, the project has already covered Mamoudzou, Tsingoni, Bandraboua, and M’Tsamboro. The latest focus is Acoua, located in the northwest of Grande-Terre, Mayotte.
Maps
LordGarySugar has created a uMap that shows pins for house names in the United Kingdom coloured by their total occurrence count from Taginfo GB.
Frederik Ramm announced that Geofabrik is now hosting its own version of the original ‘ÖPNVKarte’, rebranded as the ‘Public Transport Map’ for international users. The company has also approached the OpenStreetMap operations team to recommend reinstating the map on OpenStreetMap.org, which had long featured ÖPNVKarte before its recent removal due to operational concerns.
OSM in action
[1] Orna, a location-based mobile role-playing game, utilises OpenStreetMap data to integrate real-world locations into gameplay. The game enhances players’ surroundings with virtual elements such as monsters and dungeons, with in-game positioning directly tied to their real-world location.
The Ministry of Public Works and Housing of the Republic of Indonesia has launched a National Road and Bridge Condition Map (Peta Kondisi Jalan), utilising OpenStreetMap data to assist travellers during the annual Mudik season. This mass exodus sees millions of urban migrants returning to their hometowns ahead of Lebaran (Eid al-Fitr). The initiative aims to provide infrastructure updates, ensuring smoother and safer journeys for holiday travellers.
Software
OpenHistoricalMap has released a renderer update that significantly improves performance by reducing vector tile sizes by 88% on average and as much as 96% in areas with dense historical boundary coverage.
ohsome-planet is a new software library, available on GitHub, that facilitates the transformation of raw OpenStreetMap history data into the GeoParquet format, making it more accessible and efficient for spatial data analysis. With ohsome-planet, HeiGIT is making a big step toward the development of ohsome 2.0.
Programming
David de la Iglesia Castro, from Mozilla AI, revealed that their team had developed AI-driven object detection and image segmentation models to map features in OpenStreetMap. As a test, he used a free Google Colab GPU to detect hundreds of swimming pools around his hometown, completing the process in about an hour.
In response to mounting (1, 2, 3) criticism, the development team has disabled the hosted demonstration and removed the upload functionality from their code, replacing it with a simple URL redirect to the editor. Acknowledging concerns over low-quality AI-generated contributions to OpenStreetMap, the team has also pledged to erase all previously submitted AI-assisted edits. In a statement, they assured the community that they are taking these steps to address the backlash and uphold mapping integrity.
To mark World Water Day, observed on Saturday 22 March, Carto Cité developed► some Overpass queries that take advantage of the OSM data model describing watercourses.
Fabio Manganiello is currently working on ‘GPSTracker’, a self-hosted solution designed as an alternative to Google Maps Timeline.
Releases
NeatNit just submitted a pull request addressing a longstanding issue on the OpenStreetMap website, where bidirectional text was not displayed correctly. While further improvements, such as fixing diary entries, are still needed, the update significantly improves the readability of changeset comments, which have been particularly challenging for right-to-left language users. Previously, users had to insert unnecessary line breaks to prevent text from becoming unreadable.
Version 8.4.1 of GRASS contains more than 80 changes compared to version 8.4.0. This new minor release includes important fixes and improvements to the GRASS tools, libraries and the graphical user interface, making it more stable and robust for your daily work. Most importantly, since the 8.4.0 release, the Python API, command line, and graphical user interface are using project instead of location for the main component of the data hierarchy while maintaining backward compatibility.
OSRM v6.0-rc1, an open-source routing engine built in C++ for use with OpenStreetMap data, has been released. The latest version includes performance improvements, enhanced algorithm efficiency, and several new features.
Did you know that …
… that OSM Fukushima regularly discusses every Japanese edition of weeklyOSM on YouTube? Would you also like to contribute to the success of OpenStreetMap? Then consider creating a YouTube channel in your language as well.
… SmallTownUSA, an automated bot on the en.osm.town Mastodon server, toots daily updates featuring US towns, with populations under 1000, that are currently under-mapped in OSM?
OSM in the media
Beate Meierfrankenfeld discussed►, in a podcast, how maps shape our world with Daniel Eschkötter, cultural and media scientist at the University of Bielefeld, Ute Schneider, historian at the University of Duisburg-Essen, and Jochen Topf, a software developer and author active in OpenStreetMap.
Other “geo” things
HeiGIT noted that Anne Schauss and Melanie Eckle-Elze participated in the German Conference on Disaster Risk Reduction (Fachtagung Katastrophenvorsorge), held on 26 and 27 March. The event brought together experts to discuss the latest developments, challenges, and opportunities in disaster risk reduction, particularly in the context of climate change.
François Savatier, of Pour La Science, reported that archaeologists have discovered 14,000-year-old carvings in the Ségognole shelter, located in the École River valley, about 60 km south of Paris. The engravings appear to depict a miniature map of the local river network, providing unexpected evidence of the cartographic knowledge possessed by Upper Paleolithic hunter-gatherers.
Business Wirereported that tech company Bending Spoons has completed its acquisition of Komoot, the Germany-based route-planning platform popular among adventurers and outdoor enthusiasts. However, the acquisition has raised concerns, with Ray Maker among those questioning Bending Spoons’ track record with previous acquisitions such as Evernote, WeTransfer, and Meetup. As uncertainty looms, users and observers worry about the potential changes to Komoot’s quality and overall user experience under its new ownership.
The Geological Service of Europe Union mantains the EGDI, a powerful and easy-to-use Web map application for visualising and querying spatial information through interactive maps, including various resources for further data analysis. This application has OpenStreetMap as its base layer and users can add layers from all the geoscientific topics EGDI covers or load a layer via a WMS address.
Following President Donald Trump’s decree renaming the Gulf of Mexico to the Gulf of America, German Google Maps users have launched an edit war over the names of local bodies of water, Spiegelreported►. By creating new points of interest, users can mark unofficial landmarks, which others can then view, rate, and comment on. In some cases, these new names have also sparked minor local patriotic disputes.
Murlidhar Mohol, India’s Minister of State for Civil Aviation, announced that multiple airlines have reported instances of GNSS interference affecting aircraft operating in and around the Amritsar and Jammu regions, which lie along India’s border with Pakistan.
Stefan Krempl, from Heise, reported that the German Aerospace Centre, in collaboration with European research institutions, authorities, and industry partners, has developed Ranging Mode, a terrestrial navigation system designed as an alternative to satellite-based solutions.
R-Mode utilises existing national maritime infrastructure, operating on medium wave and very high frequency radio signals, to provide a cost-effective backup navigation service that enables ships to determine their position without relying on satellite-based systems.
Over the past seven years, an R-Mode test field with eight transmitters has been established, covering about 800 km from Helgoland to Stockholm. In 2025, it will expand to include Finland and Estonia.
Upcoming Events
Where
What
Online
When
Country
Green Open Data Day (ou Dia Verde dos Dados Abertos)
2025-03-31 – 2025-04-01
Seropédica
Green Open Data Day 2025 (ou Dia Verde dos Dados Abertos 2025)
2025-03-31 – 2025-04-01
Saint-Étienne
Rencontre Saint-Étienne et sud Loire
2025-03-31
Santa Maria Maior
Missing Maps Lisbon Mapathon with MSF
2025-04-01
Salzburg
OSM Treffen Salzburg
2025-04-01
Missing Maps London: (Online) Mapathon [eng]
2025-04-01
San Jose
South Bay Map Night
✓
2025-04-02
Stuttgart
Stuttgarter OpenStreetMap-Treffen
2025-04-02
OSMF Engineering Working Group meeting
2025-04-04
City of Canning
Social Mapping Saturday: Rossmoyne
2025-04-05
OSMF Affiliation Focus Group Discussion: Thematic and non-geographical groups
2025-04-05
New Orleans
A Synesthete’s Atlas: Cartographic Improvisations between Eric Theise and Carl Stone
2025-04-06
Delhi
15th OSM Delhi Mapping Party (Online)
2025-04-06
Salt Lake City
OSM Utah Monthly Map Night
2025-04-09
Hamburg
Hamburger Mappertreffen
2025-04-08
München
Münchner OSM-Treffen
2025-04-08
Bern
Berner OpenStreetMap-Znacht
2025-04-08
Zürich
Missing Maps Zürich Mapathon
2025-04-09
Camerino
OpenStreetMap: Mapping & Hiking
2025-04-10
Bochum
Bochumer OSM-Treffen
2025-04-10
København
OSMmapperCPH
2025-04-13
Delhi
15th OSM Delhi Mapping Party
2025-04-13
中正區
OpenStreetMap x Wikidata Taipei #75
2025-04-14
Note: If you like to see your event here, please put it into the OSM calendar. Only data which is there, will appear in weeklyOSM.
1. Who are you and what do you do? What got you into OpenStreetMap?
I work in the field of geomatics and have been contributing to OpenStreetMap for many years. I started contributing to OpenStreetMap in 2012. Then I contributed more and more. In 2017, I joined the cooperative company Champs-Libres, where I work, because it was the only company working with OpenStreetMap data in Belgium. So you could say that I found my job thanks to OpenStreetMap.
I’ve always been interested in cartography. After my studies, I started to get interested in software for making maps on the web, at the time MapServer and OpenLayers… My aim was to make maps, especially on the web, to show things that weren’t very visible. For example, I made a map of community gardens in Brussels in 2010. Then I slowly saw the rise of OpenStreetMap. But at first I didn’t believe in it: the map was mainly empty and had poor accuracy, so I didn’t think OpenStreetMap would ever be mature enough to make good maps. I was wrong.
Today I’m an active contributor to OpenStreetMap and I’m also a member of the OpenStreetMap - Belgium local chapter association. I often meet other contributors in Belgium, and we form a super-community: people who are open and passionate! I regularly co-organise OpenStreetMap meetings in my region and I lobby for OpenStreetMap just about everywhere!
2. What is the OpenArdenneMap project and why was it created? Who uses it? How?
When I started contributing to OpenStreetMap, I quickly became interested in generating topographic maps. I first saw the OpenTopoMap project, then a project to reproduce the maps of the national geographical institute in France. At first, my challenge was to be able to produce maps that looked like those of the Belgian National Geographical Institute. It was above all a technical challenge for me, as I was just starting to learn how to code. I spent a long time looking for the best software for this. First I tried MapServer, which I knew. Then I switched to Mapnik, which is the cartographic software used to generate the basic style available on openstreetmap.org and on lots of other cartographic projects, including OpenTopoMap. Very recently, in 2022, I translated the OpenArdenneMap style into QGIS.
Today, OpenArdenneMap is a cartographic style that can be used with Mapnik or QGIS, the 2 being maintained in parallel without being 100% equivalent. OpenArdenneMap is a style designed for printing, not for web maps. The main difference between a map style for printing and web maps is that the labels are about twice as large as on a web map, but there are other subtleties, such as the choice of colours, contrast, etc. I use this style with my colleagues to generate maps that can be downloaded from the hiking.osm.be website. These maps are free to download and a financial contribution is requested from those who use them. There is a rather good commercial potential with this hiking.osm.be project, for instance to propose some paper maps to sell in touristic places, but so far we did not take the time to develop it.
BTW, I’ve discovered that the style has already been used by tourist operators in Belgium to print maps on tourist boards. Finally, I use it from time to time to create large-format maps for friends or family, or just for myself like this large 2 x 1m map of the Semois river. And there’s also an OpenArdenneMap tile server, although the style is primarily intended for printing, not the web.
3. What are the unique challenges and pleasures of mapping hiking maps, especially those designed to be printed? What aspects of the projects should the rest of the world be aware of?
There are huge challenges in making printable maps from OpenStreetMap data, and I think a lot of them haven’t been addressed yet. When you look at old topographic maps, they are generally of great graphic quality and have great aesthetic power. For me, topographic maps generated from geographic data don’t have the same power, for all sorts of reasons.
Clearly, a breakthrough came when cartographers created maps from geographic data instead of drawing them on paper. About ten years ago, I learnt that cartographers at the Belgian IGN did not necessarily digitize features on aerial images according to their exact location but according to a ‘cartographic common sense’: this means that they took certain liberties with the position of some features, in order to think straight away about creating the map.
In OpenStreetMap, there’s this famous principle: ‘Don’t map for the renderer’. Of course I understand that, but if you want a map, you want to map for the renderer. My leitmotif for the future of OpenArdenneMap is precisely this: to find techniques for moving from a geographic database to a printed map. This involves a whole host of techniques that are currently very little used in the OpenStreetMap community: cartographic generalisation, displacement, etc. - in short, all the cartographic techniques that have been theorised and put into practice throughout the development of cartography.
In this sense, I agree with Christof Horman’s analysis: even if the ‘carto’ style is a fabulous work of cartography and probably the most advanced cartographic style built from OpenStreetMap data, it is still a long way from the best cartographic practices. And the same applies to all the styles derived from OpenStreetMap using Mapnik or QGIS: they fail to produce high-quality topographic maps. Of course, you could argue that a manual pass is always needed to refine a map made with an automatic style, and this is probably still true, even in the age of artificial intelligence. But apart from that, there is clearly a lack of basic cartographic work that is still not applied in styles, or even implemented in algorithms. This is a long-term project that I’d like to carry out: a review of the use of advanced mapping techniques in the OpenStreetMap ecosystem.
To come back to OpenArdenneMap, as its name suggests, it’s designed for one region in particular: the Ardennes. A friend once asked me to produce a map of Brittany using OpenArdenneMap and then complained that the sea didn’t appear. Of course, there’s no sea in the Ardennes. Far from any chauvinism or nationalism, the idea is to create a rendering specific to a region, with its own characteristics and particular objects, and of course this can evolve over time. For example, there is a specific rendering in OpenArdenneMap for Christmas tree plantations, because they cover a large area in the Ardennes, perhaps 10% of the agricultural area. But this is a recent development, and it’s possible that in a few decades there won’t be any left.
One disadvantage of web maps is that we are witnessing a standardisation of styles, with styles that can be designed for a Californian environment and then applied in Europe: this makes no sense. Each region has its own geographical richness, the result of the evolution of the natural landscapes inhabited by the human communities who have lived there. And so each region is entitled to its own styles, which highlight its characteristics.
4. What have you learned? What is the best way for people to do something similar in their city or region or country?
I try to collect maps from my region and elsewhere, and compare them. This gives me ideas for developing new things in my cartographic style. OpenArdenneMap is a rather “vintage” style, but I also like to add more recent elements to the landscape, like wind turbines. I don’t do it enough, but I also try to follow what’s being done in other mapping projects like OpenTopoMap or the ‘carto’ style of osm.org. For example, I’ve taken up the idea of automatically orienting the names of water bodies according to their shape. Or orienting sports fields and church symbols according to their actual orientation on the ground.
A cartographic style affects many things: for example, you can spend a lot of time choosing suitable fonts. For OpenArdenneMap, I chose a font made in Belgium via a magazine, Medor.coop, and then I finally met its designer, who is also a cartography enthusiast. It’s the Alfphabet font, which reproduces a font used in the 1950s. In OpenArdenneMap, I try to display a lot of labels, so the font is important.
I also like drawing symbols and pattern symbols. I’m not very good at drawing in general, and I can’t see myself creating logos, but for map symbols, I find it quite easy.
Then there’s printing. That’s quite an art too! I’ve learnt the difference between offset and digital printing. Older maps were often printed in offset with true colours: this enhances their quality. This is one of the reasons why OpenArdenneMap only has 3 colours + black: it allows offset printing with true colours.
For those who want to start a cartographic style, I recommend starting with an existing style (in Mapnik or QGIS) and then gradually changing the colours, textures, what is displayed and what is not, etc. If you want to define a style that is available for several scales, starting from a blank page takes an enormous amount of time.
5. What steps could the global OpenStreetMap community take to help support projects like this?
I love seeing new cartographic projects being created. And we certainly still need to maintain the old ones, in any case there is potential for improvement even in old styles. As I said earlier, there’s a lack of techniques and algorithms that can be used for cartographic generalisation, specifically with OpenStreetMap data. One of the challenges of OpenStreetMap data is its lack of completeness and uniformity: sometimes you have to avoid to represent something on a map if it isn’t mapped everywhere. For example, I won’t show isolated trees if their distribution in my map area is too irregular. But for this kind of problem, it’s more up to the cartographer to find or develop algorithms for data preparation and cartographic generalisation.
I think there’s a lack of documentation on existing cartographic projects. At the same time, we probably don’t have enough experience of creating maps with OpenStreetMap.
6. Last year OpenStreetMap celebrated 20 years. As someone who has been very active in OpenStreetMap for a long time, where do you think the project will be in another 20 years?
I’m sure that the project will still be there, with its community. It may be difficult to recruit new contributors, but I’m not so sure. Already today, most people use OpenStreetMap without knowing it, because OSM data is integrated into a lot of different applications. This will certainly increase in the future. Perhaps whole areas of OSM use will be supplanted by other databases, for example for the road network, addresses or POIs. But the project will always be there for mapping enthusiasts. Maybe it will be reserved more for hobbyists.
In Belgium, we are increasingly approached by public authorities who are interested in contributing to OpenStreetMap, for example by local authorities who tell us about changes in the road network. We’re also trying to get public authorities to reuse the data, and there are more and more use cases. I’m sure that this will continue to develop in Belgium.
Thank you, Julien, for taking the time to share your insights. Wonderful. As an avid hiker, I love this style. But most of all I love the perspective that we need a rich diversity of mapping styles to capture the rich diversity of the world. And open data and open source tools make it possible.
Jste zkušení geodeti, nebo běžně používáte mapy. S GIS softwarem pracujete denně.
Situace
Ale teď potřebujete tvořit zákres do mapy se skupinou lidí, kteří nemají pokročilé mapovací zkušenosti a s počítačem také nejsou zrovna kamarádi. Nástroj mapování se tedy musí přizpůsobit jejich schopnostem. Zaznamenávat data do veřejné mapy není vhodné, potřebujete jen aktuální a přesnou podklad
Jste zkušení geodeti, nebo běžně používáte mapy. S GIS softwarem pracujete denně.
Situace
Ale teď potřebujete tvořit zákres do mapy se skupinou lidí, kteří nemají pokročilé mapovací zkušenosti a s počítačem také nejsou zrovna kamarádi. Nástroj mapování se tedy musí přizpůsobit jejich schopnostem. Zaznamenávat data do veřejné mapy není vhodné, potřebujete jen aktuální a přesnou podkladovou mapu.
Kdo s mapováním pomůže?
Mohou to být například:
Děti z dětského kroužku, které jsou sice šikovné na všechno možné, ale na QGIS nebo jiné profi aplikace mají ještě několik let času. Nedává smysl je obtěžovat s počítačem, když síla jejich schopností je v pozorovacím talentu. Tak je využijte a k počítači se vraťte později.
Lidé v krizové situaci, kterým právě katastrofa rozbila obydlí a nemají u sebe nic než oblečení a klíče od domu, který už neexistuje. V jejich momentálním rozpoložení budete těžko hledat soustředění, ale zároveň by bylo dobré upřesnit na mapě, co ve skutečnosti už je jen změť trosek. Dílo zkázy napáchala velká voda, oheň, nebo zemětřesení? Co když je potřeba je přesně lokalizovat a zároveň mapě dodat bližší metadata?
Senioři bez mapových zkušeností, kteří na kopcích za dědinou mají políčko, pastviny, vinohrad a ovocný sad… Rodnou ves znají velmi dobře, ale kdepak na ně s nějakou mobilní aplikací! Požádate je o pomoc, máte sice satelitní mapy, ale pantáta na ně slabým zrakem nevidí. Satelitní mapy neznají některé detaily, které znají ti dobří lidé ze vsi. A o ty právě jde.
Malozemědělci, nebo terénní ochránci přírody kteří jsou celý rok spíše venku, než doma. Počítače mají, ale v lese, v krajině, v nevlídném počasí je přeci nebudou používat. Data která zakreslí ručně, se do veřejné mapy nedostanou, ale přesto jsou velice důležitá na pozdější mapovou analýzu.
Týmy dobrovolníků z neziskové organizace realizující projekt participativního mapování je další případ. V situaci, kdy je potřeba úkolovat více různě zkušených dobrovolníků a jejich činnost probíhá na velkém území s nejasně definovanými plochami. Každý dobrovolník může používat vlastní mapu pro své okolí. Data nakonec musí být sjednocena do jedné georeferencované vrstvy, aby byla použitelná v GIS.
Netvrdím, že budu chytřejší než armáda, ale mohou to být i situace, které byste raději nechtěli zažít. Polní podmínky, kdy na místě a v čase žádné elektronické zařízení není bezpečné a data shromážděná z tady a teď v terénu, se dostanou do počítače až později. Přesto je potřeba mapovat a hlavně v té přesné formě předat. Digitalizace musí být co nejrychlejší. A doporučil bych nepoužívat Starlink.
This blog post is part of a series of blog posts about the new OSM file format “OMA”. This is the fourth post. At the end of the article you’ll find links to the other blog entries.
The real subject of this blog series is the newly developed file format. So far I have mainly talked about the tools for creating and using the format, because the format itself is a dry subjec
This blog post is part of a series of blog posts about the new OSM file format “OMA”. This is the fourth post. At the end of the article you’ll find links to the other blog entries.
The real subject of this blog series is the newly developed file format. So far I have mainly talked about the tools for creating and using the format, because the format itself is a dry subject. But now it’s time to dive more deeply into the format itself. I will not go into all the details, because I think that apart from some freaks like me, people are not interested in all the details. If you are, take a look at the specs.
Fast Access
OpenStreetMap data consists of a set of elements. Some of these elements are nodes, some are ways, and some are relations. You can think of OSM as a big storehouse where all the elements are scattered around:
Obviously it’s hard to find what you’re looking for, if there is no order.
The Order of OSM Files
Fortunately, it’s not that bad. In traditional OSM files there is some order: Elements are sorted by type and, as a second criterion, by ID.
This order doesn’t help much, when looking for certain elements. Especially: You can’t take an element out of the middle and look at it, you have to go through the elements from top to bottom.1
The Order of Databases
Because it’s hard to work this way, many ways of sorting OSM elements have been developed over time. For example, in a database they can be stored as tables with one element per row and one table for each type. You can think of this as storing nodes in one room, ways in another, and relations in a third room in our storehouse.
Typically, databases also contain some indexes. In our analogy, they are like posters at the entrance to each room, telling you, which shelf to look on for a particular element. Indexes are very important for quick searching.
The Order of OMA Files
Oma files sort elements on three levels: First by type and geographic location, second by key, and third by value. They contain something like a database index at each level, so typical searches can be handled very quickly.
In our analogy, you might think of the rooms in the building as the first level, the shelf units in each room as the second level and the shelves in each shelf unit as the third level; again, with posters at each level.
Small Filesize
The second design goal was to keep the file size small. Two mechanisms are used for this: Efficient storage of the elementary datatypes and compression. There are basically three elementary datatypes to handle: geographic coordinates, integers and strings.
Geographical coordinates
Coordinates in OSM data are given as a pair of numbers expressing longitude and latitude in the WGS84 coordinate system. A naive approche of storing them would be as a pair of floating point numbers. For full accuracy you would need to use double precision numbers, resulting in 16 bytes per coordinate.
That’s a lot. For example, germany.oma contains 576,208,086 pairs of coordinates. At 16 bytes per pair, this alone would result in a file size of over 8 GB.
It would be possible to use single precision numbers, accepting some small rounding errors. This would halve the number of bytes used. But there are better ways: If you multiply each number involved by 10,000,000, the two coordinates become integers that can be stored in 8 bytes without loss of precision.
This can still be improved using a technique called delta encoding: Two consecutive nodes in the file are often close to each other. So the difference between the coordinates of these two nodes is a much smaller number that can be stored in fewer bytes.
In Oma files, if the difference between two coordinates is between -32767 and 32767, this difference is stored, using only 2 bytes. This case is used in 94% of all coordinates. If it’s larger, 6 bytes must be used. This results in a total of 4,4 bytes for a pair of coordinates on average, almost halving the amount needed again.2
For comparison, the pbf and o5m formats use a similar, but slightly more complicated delta encoding. The result is the same: an average of 4,4 bytes for a pair of coordinates.
Integers
If you look carefully at OSM data, there are many places where there are small non-negative integers (the number of tags of an element, the number of nodes of a way, the version number, and so on). A normal integer takes up 4 bytes of space, and that’s a waste when the numbers are so small, because almost always 3 of those 4 bytes are just zeros. That’s like writing 0008 instead of 8.
So, Oma files store integers smaller than 255 in just one byte. Integers between 255 and 65534 use 3 bytes, and all larger integers use 7 bytes. On average, this results in 1,006 bytes per integer, which is almost perfect (using germany.oma as a reference).
Strings
There are a lot of repetitive strings in OSM data. Imagine how many times the string highway alone occurs. It would be nice to store these strings more efficiently. Other formats use lookup tables to do so. For example, the lookup table might contain highway at position 3, so instead of storing the string highway, the number 3 could be used.
I have experimented with such lookup tables too, but they turned out to be a bad idea. Why is that? Well, the whole thing is piped through a compression algorithm called deflate. This algorithm is very good at recognising repetitions, and so the repeated highway strings can be compressed better than repeated occurrences of 3.
It turned out, that table lookup mechanisms together with deflate increased the file size instead of reducing it.
So I didn’t do much with strings. There is only one small difference from the standard way of storing strings (in Java): I do not use a two-byte value to store the length of the string, but an integer, as explained above, which most of the time uses only one byte.
Compression
All slices can be compressed using an algorithm called deflate. This is a very old and well-established algorithm. It was developed back in the eighties and is used in zip files, pbf files and many other places.
Well, I didn’t think any more about compression – it worked, so what?
In a comment to my introductory post, user cello pointed out, that there are better algorithms available today. They are about 5 to 10 times faster, often with similar or even better compression.
I don’t know how well these algorithms will work together with the element storage decisions I wrote about above. They probably need to be added to the tools to find out. I haven’t found the time to do that and I probably won’t find the time to do so in the near future.
But I thought I could calculate rough estimates of the speed gains of these algorithms. All I had to do was measure the time taken by the deflate algorithm and divide it by 5 or 10. Unfortunately, the measurement produced some very strange results, leaving me with very little information to estimate.3
It could be, that the speed gain is almost nothing, or even a loss. It could also be that access times are halved. I can’t predict.
I thought for a long time about what to do with these new compression algorithms. Yesterday I finally forced myself into a decision: I will not include them in version 1 of the file format. It would take too many resources on my part and I can’t tell yet if anyone (besides me) will use OMA files anyway. But I definitely plan to include these algorithms in version 2 of the file format, when the time is ripe.
The analogy of a stack is somewhat missleading here. Actually you can look at every place in the pile, but you do not know, where one element ends and where the next starts. I described this in more detail in my introductory post. ↩
Oma files do not restrict the order of elements in a slice. If they where sorted in an approbriate manner, the average amount of bytes needed could probably be reduced to almost 4,0. I never tried this though. ↩
I used two versions of germany.oma: One compressed, the other not. The second one is about three times larger as the first one. Reading the whole file byte by byte takes 1 minute for the first one and 3 minutes for the second one; that’s what I expected. Next, I used these two files to read them with an OmaReader. I used an empty filter which means, that all elements are read. I expected this to be slower in both cases. While this was true for the compressed version (took now about 2 minutes), it was not true for the uncompressed version (took only 1 1/2 minutes). I have no clue why reading the whole file while jumping around in the file and doing some additional compution with the bytes is much faster than just reading the file sequentially… ↩
OpenStreetMap Blogs
図示した橙色経路が新しい経路なのだが、旧道・旧橋梁経由の方がルートとして短距離かつ右左折回数についても有利（旧ルートについては実質0回で道なり）である。それゆえか、執筆時点でも図右側のGoogleMapでは閉鎖された旧橋梁経由が案内されるため、特に南下する利用者については橙色のフェンスを見て立ち往生する様子が現地調査中だけでも3輌見受けられた。
Jacobina, BA
Rapid Editor 
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a report on the OpenStreetMap 
a mapping talk series titled ‘Improving Data Quality of Road Mapping’. The session featured M. Iqnaul Haq, Maps Ops Manager at GoTo Group, who discussed the crucial 
every Japanese edition of weeklyOSM on YouTube? Would you also like to contribute to the success of OpenStreetMap? Then consider creating a YouTube channel in your language as well.
