DEM Generation

Name: “dem_generation”

Description

Generates dem from a DSM. The details in the DSM allow to create upper and lower dems. The DEMs generated are less resolved than the input DSM.

Up to 4 dems are generated, with different methods:

median
min
max
initial_elevation_fit (only if coregistration is set to true)

The DEMs are generated in the application dump directory. You can find the shift values applied to the initial elevation in metadata.json.

Configuration

Name	Description	Type	Available value	Default value	Required
method	Method for dem_generation	string	“bulldozer_on_raster”	“bulldozer_on_raster”	No
height_margin [1]	Height margin [margin min, margin max], in meter	int		5 [1]	No
min_dem	Min value that has to be reached by dem_min	int	should be < 0	-500	No
max_dem	Max value that has to be reached by dem_max	int	should be > 0	1000	No
coregistration	Use the median dem to correct shifts in the initial elevation provided	boolean		true	No
coregistration_max_shift	Maximum shift allowed on X/Y axes for the coregistered initial elevation	int, float	should be > 0	180	No
save_intermediate_data	Save DEM as TIF	boolean		false	No
margin [1]	Margin to use on the border of dem: [factor_of_dem_size, margin_in_meters]	list	should be > 0	[0.2, None [1] ]	No
fillnodata_max_search_distance	Max search distance for rasterio fill nodata	int	should be > 0	50	No
morphological_filters_size	Size (in pixels) of erosion and dilation filters used to generate DEM	int	should be > 0	30	No
preprocessing_median_filter_size	Size (in pixels) of first median filter used to smooth median DEM	int	should be > 0	5	No
dem_median_downscale	Downsample factor on dsm to generate median DEM	int	should be > 0	10	No
dem_min_max_downscale	Downsample factor on dsm to generate DEM min and DEM max	int	should be > 0	2	No
postprocessing_median_filter_size	Size (in pixels) of second median filter used to smooth downsampled median DEM	int	should be > 0	7	No
bulldozer_max_object_size	Bulldozer parameter “max_object_size”	int	should be > 0	8	No
compute_stats	Compute statistics of difference between DEM min/max and original DSM	boolean		true	No
disable_bulldozer	Disable Bulldozer step to fasten the DEM generation	boolean		false	No
resolution	The resolution of the dems	int, float	should be > 0	0.5 [1]	No

Example

---
applications:
  dem_generation:
    method: "bulldozer_on_raster"
    fillnodata_max_search_distance: 60

{
    "applications": {
        "dem_generation": {
            "method": "bulldozer_on_raster",
            "fillnodata_max_search_distance": 60
        }
    }
}

Footnotes