Budapest city heat map:mapping the hottest spots and cooling options in the city.
Cities never heat up evenly. Pavements, roofs, tree canopies and courtyards store and release heat at different rates, creating microclimate hotspots that traditional weather gauges cannot detect. High-resolution heat maps reveal this hidden mosaic of heat. They show which roofs require reflective coatings due to being heated by the sun, which asphalt street sections or parking lots need shade, and which leafy areas already act as coolers. In other words, a good heat map transforms the general feeling of ‘summer heat discomfort’ into concrete information that can be used by planners, designers and residents.
To make this information accessible to all, we have launched an interactive web portal covering the central areas of Terézváros (District VI) and Erzsébetváros (District VII), with plans to expand to other areas soon: https://city.can.hu/osm-orto-heat-layers.html
What information can you find on the map portal?
You can navigate between the following map layers:
- Orthophoto viewing: View high-resolution orthophotos of Terézváros and Erzsébetváros.These provide detailed aerial views of the districts.
- Thermal Image Viewing: Users can access and explore thermal images covering the entire districts, captured by remote thermal cameras. Thermal images display temperature variations across the landscape.
- Predicted thermal images:The platform offers predicted thermal images, generated from orthophotos using a CNN model. These predictions provide insights into potential thermal distributions based on the orthophotos.
- OpenStreetMap Layer: An OpenStreetMap (OSM) layer is available to provide contextual geographical information. Users can overlay the OSM layer with orthophotos and thermal images to enhance navigation and analysis.
You can switch between layers and easily zoom in on the map. Seamlessly scan from a panoramic view of the area to individual rooftops. You can compare layers, Place the raw heat data collected by drones alongside the ortho photo or the predictions generated by AI to judge the model’s accuracy for yourself. Our open-source Convolutional Neural Network (CNN) model can be used by researchers and other cities. It is available at this link.
How the map was created?
We flew DJI Mavic 3 Thermal drones on cloudless summer afternoons in 2023, when roofs and pavements were at their hottest. You can read more about the drone survey here. After calibrating the surface emission factor, the images were stitched together into centimetre-sized orthomosaics with geographic references. At this resolution, even the cooling effect of a single street tree becomes apparent.
How can you analyse the heat map?
You can analyse the data visually. You can see the surface temperature by zooming in on the area you’re interested in. Hot surfaces, such as dark roofs and fresh asphalt, appear bright red. Cool zones, including light-coloured roofs, shaded areas and reflective membranes, appear in soothing shades of blue.
You can download the raw heat map data from this link and use it as a separate layer for your own analysis, provided you comply with the copyright information.
You can run analysis scripts on the heat maps. One such analysis script can be downloaded from this link.
Why are these maps important?
With the help of heat maps, we can now identify specific roofs, streets and playgrounds where urgent action is needed. Community groups use the maps in workshops to demonstrate to neighbours why a patch of asphalt can be so oppressive and how it could be transformed by planting a few trees. As the portal is part of a GIS environment, users can instantly switch between standard and heat maps to provide indisputable evidence.
For larger-scale projects affecting the city’s infrastructure (e.g. creating pedestrian zones, renovating roofs, or planting new trees), we repeat the drone flights. Side-by-side ‘before and after’ maps provide convincing evidence of what works and help secure funding for the next round of interventions.
Discover it for yourself!
The portal is live, and the code and measurement data are publicly available. Budapest’s invisible heat patterns can be explored more effectively and converted into useful knowledge.