Open-source mapping for disaster response

At FOSDEM 2026 Petya Kangalova, a senior tech partnership and engagement manager for the Humanitarian OpenStreetMap Team (HOT) spoke about how the project helps people map their surroundings to assist in disaster response and humanitarian aid. The project has developed a stack of technology to help volunteers collectively map an area and add in local knowledge metadata. "One of the core things that we believe is that when we speak about disaster response or people having access to data is that they really need accessible technology that's free and open for anyone to use."

I was not able to attend FOSDEM 2026 in person, but watched the session via FOSDEM's live stream. The video and slides from the session are available on the FOSDEM 2026 talk page.

HOT is a separate entity from OpenStreetMap (OSM), the grassroots endeavor to map and annotate the globe. But HOT, a non-profit non-governmental organization (NGO), cut a deal to use the OSM name and maps, as well contribute its work back to OSM's maps. LWN first covered HOT in 2014. The project focuses on "blank spots", which are areas of the world that lack maps, and especially those areas suffering (or might easily suffer from) a disaster such as a hurricane or volcano activity. Disasters around the world can kill hundreds of thousands of people and leave millions displaced each year. People, especially in dire circumstances, "need technology that is open and free", Kangalova said.

HOT recruits volunteers to collect imagery with drones, and provides tools to annotate important details of maps it creates, such as buildings and roads. The results are submitted to OSM and shared with local disaster-relief agencies. Thus far, the project has mapped more than 175 million buildings and 3.8 million roads, thanks to more than 540,000 mappers.

Essential to this mission is a full end-to-end mapping workflow built on a set of open-source tools. This software is collaborative in nature. It is designed to be used by many people simultaneously to form composite, annotated maps. It is also designed to be easy to use for people with no experience in geographic information systems (GIS).

Haitian earthquake

HOT was born 15 years ago, in response to a 7.0 magnitude earthquake in Haiti that left more than 300,000 dead and more than a million displaced. "When the earthquake happened, there were no maps available" for respondents to work from, Kangalova said. At the time, Google had mapped the main roads, but the government held the only local maps detailed enough to be useful to relief workers. Those maps, however, were housed in buildings damaged by the quake. Within 48 hours, the OSM community had cobbled together a set of satellite imagery for the area.

OSM has a pretty comprehensive coverage of the US, Europe, and Australia. Kangalova noted that HOT, now with about 70 full-time employees throughout the world, set up hubs for the under-mapped regions of Latin America, the Caribbean, Africa, and Asia. Projects have been done and documented for Argentina, Bangkok, Bali, Nepal, and Sierra Leone, as well as many other spots. Anyone can view and edit the maps. The intended users are "local governments making decisions about the specific infrastructure. Sometimes it's around specific routes and sometimes it's about reaching people post-earthquake and other disasters", Kangalova said.

The goal is to support local efforts to generate data of their own communities so that when an emergency happens that data will be on hand, Kangalova said. Local governments and humanitarian aides can then use the maps and related data they need during times of duress. The project helped the Balinese Disaster Management Agency in Indonesia to map evacuation routes for those near Mount Agung, an active volcano.

After 50 years of near silence, Mount Agung started awakening throughout late 2017 into early 2018, resulting in several full-blown magmatic eruptions, as well as considerable shocks with earthquakes of magnitude 4.0 and higher. According to the Indonesian Ministry of Energy and Mineral Resources, more than 10,000 residents had to be evacuated from the area around the mountain. They were from the hamlets scattered through the mountainous highland regions that surround the mountain. The winding roads were not clearly documented, so an early warning system was clearly needed.

For the project, employees of the Balinese agency learned how to operate the drones and the accompanying software, according to HOT's summary video. The drones provided high-resolution aerial imagery, which were used to scout for locations for early warning systems. The imagery also allowed the agency to identify the exit routes, and publish a contingency plan for volcanic eruptions.

Mapping by the many

HOT's approach is collaborative and iterative. The first step is gathering imagery. No imagery, no map. A first pass can be provided by satellite, but more detailed imagery is also needed; it is procured by a coordinated set of drones, traveling around 100 meters or so above the land. The software stitches together the imagery and metadata. It then calls on residents to supply information about the landmarks. This last part is the most crucial: the local knowledge. "We can all see this is a building, but what is it?" Kangalova said.

HOT recommends using a number of relatively low-cost drones for the task of gathering data; currently the DJI Mini Pros versions 4 and 5, as well as the Potensic Atom drones are supported. An area needing to be mapped is separated into field-mappable chunks, with the results combined into a single entity. The HOT stack is a mix of tools it developed in-house along with open-source-mapping software added to fill in the gaps.

Kangalova discussed the whole stack, technology by technology. To create the flight plans, HOT created Drone Tasking Manager (DroneTM). Unlike other mapping technology, this software can split a flight plan into separate tasks run by different individuals. The project uses OpenDroneMap, a third-party open-source-mapping application, to process the imagery and make it GIS-ready. The results are fed into another third-party tool, OpenAerialMap, to store and display aerial imagery, making it available for searching via an API or by the web.

With this imagery, volunteers can independently annotate different sections, identifying roads, bridges, and the like. This work is coordinated by the HOT Tasking Manager. An AI-powered assistant, fAIr, may be used to help fill out information with local models trained on local data. Those on the ground can contribute what they learn through the Field Tasking Manager, a standalone mobile and web application. It is integrated with third-party open-source projects OpenDataKit and QField to build the forms and templates.

Commercial applications can also be used to collect data, Kangalova said. ChatMap creates maps and associated artifacts from messaging applications such as WhatsApp and Telegram. Data from a user's location can be uploaded, along with any associated notes and imagery. Creating maps from all this OSM imagery is the job of uMap, an open-source GIS tool developed by OpenStreetMap France, which integrates the maps with other data. A HOT export tool can be used to download OSM imagery for other applications.

All of HOT's projects and tools are on GitHub and the project welcomes contributions. "All the projects that I've mentioned, you see the repositories, their current current volunteer projects, and ways to get involved", Kangalova said.

HOT has created a wealth of open-source technologies to help communities map their surroundings in a collaborative way. Perhaps more importantly, it does the legwork of assembling this stack of open-source software to execute a specific mission, a formidable task for outsiders. And then during times of duress, it trains volunteers to quickly get results. In doing all this, HOT fulfills one of the most vital missions of open source, to help people everywhere through the power of software.