ELEVATION MODELSComing soon
Create a DEM, DSM and DTM from Drone Images
Stream Capture builds the digital surface model (DSM) and the bare-earth digital terrain model (DTM) straight from your drone photos. Every elevation raster ships with a mask that says which cells were measured and which were filled, and with an optional map of how far to trust each cell.
Stream Capture is in development and not released yet. At launch it will come in the same download as its sister program Stream Terrain; today's download contains Stream Terrain.
DEM, DSM and DTM: which one do you get from drone photos?
A digital elevation model (DEM) is a raster grid of heights. Photogrammetry sees the top of whatever the camera sees, so the first surface it can produce is a DSM — ground plus vegetation, buildings and stockpiles. A DTM is the bare ground; it has to be derived by classifying which points are ground.
Stream Capture produces both in one run. The DSM comes from the dense surface; the DTM comes from a ground filter on the classified point cloud, and wherever the filter had to fill in, the mask says so.
DEM from Drone Images in STREAM
DSM and DTM in the same run
Tick both in the products list. They are written on the same cell lattice as the orthophoto, so the three overlay pixel for pixel in GIS.
An honesty mask beside every DEM
A second raster labels each cell: measured, interpolated, modelled water level, constrained by a breakline, or water where no height was produced. Gaps are labelled, not painted over.
A confidence map on request
A three-band GeoTIFF classes each cell as clean measurement, filled, high scatter or discontinuity (an edge or a steep face), and gives the height scatter inside the cell. It is an estimate of trust, not a guarantee of accuracy.
Water handled on purpose
Water surfaces can be modelled at a water level or left empty. The choice is yours and the mask records which cells were affected.
Height you can reference
Choose ellipsoidal heights or orthometric heights with a geoid model. With enough ground control the DSM and DTM can also be shifted vertically to the surveyed heights; see the ground control page.
Change against an earlier flight
Choose an earlier project of the same site and the new DSM is compared with it: a difference raster where positive values are fill and negative values are cut.
Slope, aspect and hillshade
Optional DTM derivatives are written on the delivery grid with the Horn method standard GIS tools use: slope in degrees, aspect clockwise from north and a hillshaded relief.
Contours and a TIN surface
Contours are written as DXF, GeoJSON, KML, Shapefile or GeoPackage. The DTM can also be exported as a LandXML 1.2 surface for civil design software.
How to create a DSM and DTM from drone images
- 1
Add the photos and confirm the coordinate system
The output grid, and every height in it, is in the coordinate system you confirm in the wizard. Choose the height datum here too.
- 2
Tick DSM and DTM
Both are in the products list of the Output step. The Process section shows each one's elevation range once it is done.
- 3
Choose the preset
Balanced writes the elevation models at twice the ground sampling distance; Maximum writes them at full resolution.
- 4
Process and inspect
Switch to the DEM view (key 4) and open the honesty mask next to it to see where heights were measured and where they were filled.
- 5
Export
The Export Center writes GeoTIFF, Esri ASCII Grid or GeoPackage, 16 or 32-bit integer rasters, contours and the LandXML surface.
Supported formats
Frequently asked questions
How do I create a DEM from drone images?
Process the photos in a photogrammetry program that builds a dense surface, then rasterise it. In Stream Capture, add the photo folders, tick DSM and DTM and press Process All; the elevation models are written as GeoTIFF with a mask that labels measured and filled cells.
Should I deliver a DSM or a DTM?
Deliver the DSM when the top surface matters — stockpiles, canopy, buildings. Deliver the DTM for bare-earth work such as earthworks and drainage. Where vegetation is dense the camera never saw the ground, so a DTM there is an estimate and the mask says so.
How accurate is a DEM from drone photos?
Height is usually the weakest axis: without ground control, a systematic vertical offset between the drone's frame and your survey frame can remain. Control points remove it, and independent check points measure what is left. Your result depends on your control and conditions.
Does it fill holes in the DEM?
It interpolates small gaps and says so: filled cells are marked in the honesty mask and as filled in the confidence map. Nothing is filled silently.
Can I open the elevation model in GIS or CAD?
Yes. GeoTIFF and Esri ASCII Grid open in GIS, contours export as DXF, and the LandXML surface imports into civil design software. Stream Terrain also opens the files directly.
Is the DTM a true bare-earth model?
It is a ground-filtered model: points are classified by a cloth-simulation ground filter and the DTM is built from the ground class. Where no ground was visible it is interpolated, and the mask records that.
Where this is used
Try DEM from Drone Images in STREAM
Stream Capture is in development and not released yet. At launch it will come in the same download as its sister program Stream Terrain; today's download contains Stream Terrain.
About Stream Capture