Elevation api

FastFlood API – Elevation Endpoint Documentation

The elevation endpoint allows users to retrieve terrain data for a specified geographic region. The API automatically collects and merges the best available elevation datasets, including high-resolution national LiDAR where available and global elevation datasets elsewhere. The resulting terrain raster is returned as a cloud-optimized GeoTIFF (COG) that can be streamed directly by GIS software or web mapping libraries.

The elevation endpoint is useful for terrain preparation workflows, flood modelling setup, or any application requiring high-quality digital elevation data.

Endpoint

POST https://webapp-prod-fastflood.azurewebsites.net/v1/model/dem

The request body must contain a JSON payload describing the area of interest and the desired resolution of the elevation model.

Input structure

The request uses the autodem parameter group. This defines the model area and the desired terrain resolution.

Example request

{
"autodem": {
"bbox": [
-6827737.551573,
1722546.650921,
-6822960.237306,
1714291.451866
],
"resolution": "high"
}
}

autodem parameters

bbox

Defines the spatial extent of the elevation request. The bounding box must contain four coordinates in the following order:

[min_x, max_y, max_x, min_y]

This corresponds to west, north, east, and south boundaries of the requested region.

The bounding box can be provided in either of the following coordinate systems:

WGS84 geographic coordinates (longitude, latitude)
Pseudo Mercator coordinates (EPSG:3857)

The coordinate order must always remain the same regardless of the projection.

Examples

WGS84 example

"bbox": [5.94, 52.21, 5.99, 52.18]

Pseudo Mercator example

"bbox": [-6827737.55, 1722546.65, -6822960.23, 1714291.45]

resolution

Defines the spatial resolution of the returned elevation dataset. The resolution parameter accepts both descriptive resolution levels and explicit grid spacing values.

Descriptive resolution levels

low
medium
high
veryhigh

These options allow the system to automatically select the most appropriate dataset for the requested region.

Explicit grid resolution values

1m
2m
5m
10m
20m
40m
80m
150m
300m
600m

These values explicitly define the output grid resolution in meters.

If very high resolution terrain data is not available in the requested region, the API will automatically select the best available dataset and resample it to the requested resolution where possible.

Example requests

Medium resolution terrain extraction

{
"autodem": {
"bbox": [5.94, 52.21, 5.99, 52.18],
"resolution": "medium"
}
}

High resolution terrain extraction using Web Mercator coordinates

{
"autodem": {
"bbox": [
-6827737.551573,
1722546.650921,
-6822960.237306,
1714291.451866
],
"resolution": "10m"
}
}

Response structure

The elevation endpoint returns a standard API response object containing a download link to the generated elevation dataset.

Example response

{
"status_code": 200,
"message": "DEM generated successfully",
"data": {
"files": [
{
"name": "dem.tif",
"type": "ModelOutputFile",
"href": "https://..."
}
]
},
"errors": null
}

Output data

The response contains a single output file representing the generated terrain model.

dem.tif

This file is a cloud-optimized GeoTIFF containing the terrain elevation raster. The raster is provided in the Pseudo Mercator projection (EPSG:3857). Because the file is cloud optimized, it can be accessed directly via HTTP range requests, which allows streaming access from web map libraries or remote GIS software without downloading the entire file.

Typical uses include:

terrain visualization in GIS software
flood modelling preparation
terrain analysis and watershed modelling
web mapping applications using MapLibre, Mapbox GL, or similar libraries

The output file remains available via the provided download URL for a limited period of time.

Recommended usage

The elevation endpoint is designed to provide terrain data for modelling workflows. In most cases users should request terrain for relatively small areas to ensure fast processing times and efficient data transfer.

Typical requests range from a few square kilometers up to regional extents depending on the requested resolution.

Higher resolutions such as 1m or 2m should be used only for small domains due to the large file sizes generated.

For most modelling workflows the following resolutions are recommended:

high or 10m for regional flood modelling
medium or 20m for large regional domains
veryhigh or 1–2m for detailed local studies

The returned DEM can be directly used as input for FastFlood simulation endpoints or imported into GIS software for visualization and further analysis.