A digital elevation model (DEM) records the changing elevation across a given surface, in this case the model of a context. DEMs are used by the excavators and others to extract elevation information on an ongoing basis, which replaces the regular collection of elevations in the field that is typical of most archaeological projects. So, it is important that the DEM is as accurate both in its horizontal (x and y) and vertical (z) dimensions.
- To create a DEM, go to Workflow> Build DEM. Make sure the type is set to Geographic and accept all defaults.
| Type | Geographic (default) |
| Projection set to | WGS 84/UTM zone 35N (EPSG: 32635) (default) |
| Source data | Dense cloud (default) |
| Interpolation | Enabled (default) |
| Point classes | All (default) |
- To export the DEM you created above, go to File> Export> Export DEM> Export TIFF
- All settings should be at default.
| Coordinate system | EPSG: 32635 (default) |
| Settings | (default) |
| Save as | TIFF |
- Unlike other products of the photobatch processing workflow, you will not save the DEM in the photobatch folder. Instead, you will save it in a folder with the orthophotos and other materials for GIS work.
- File path: E:\gygaia\gisgps\kap\[year]\rasters\photoscan_exports\[EA]
- File name: Z[photobatch number] (e.g., Z201905241242)
- Double-check 1) that you are saving the DEM under the correct year and the correct excavation area and 2) that you use the correct file prefix (in this case, Z), or it will be difficult for the excavators to find what they need to draw their day plans.
- Now you can continue to build and export the orthophoto, or move on to the next step in the workflow.