riverarchitect.volume_assessment

Earthworks quantities from a pair of DEMs.

Compares an original (pre-project) and a modified (post-project) digital elevation model and reports the fill and excavation volumes required to get from one to the other, together with the affected areas.

This is the open-source port of the former VolumeAssessment module. Beyond dropping arcpy and the 3D Analyst licence it changes two things of substance:

• Volumes are integrated under the triangulated surface (riverarchitect.volume) rather than parsed out of a geoprocessing message string.

• The two DEMs are explicitly aligned onto a common grid. The original relied on arcpy.env.extent to reconcile differing extents silently, which is the single most likely source of quietly wrong numbers when the modified DEM covers a different footprint.

Example

from riverarchitect.volume_assessment import VolumeAssessment

va = VolumeAssessment("dem.tif", "dem_modified.tif", unit="us")
result = va.run(output_dir="Output/volumes")
print(result["fill_volume"], result["excavation_volume"])

class riverarchitect.volume_assessment.VolumeAssessment(original_dem, modified_dem, unit='us', level_of_detection=None)

Bases: object

Compare two DEMs and quantify the earthworks between them.

Parameters:

• original_dem (str) – path to the pre-project DEM.

• modified_dem (str) – path to the post-project DEM.

• unit (str) – "us" (feet, reported in cubic yards) or "si" (metres, cubic metres).

• level_of_detection (float) – elevation changes with a magnitude below this threshold are treated as survey noise and ignored. Defaults to 0.99 ft for "us" and 0.3 m for "si", matching the original module.

difference()

Compute the DEM of Difference (modified minus original) on a common grid.

Returns:

(dod, profile). Positive values are fill, negative are excavation.

Return type:

tuple

volumes()

Fill and excavation volumes from the DEM of Difference.

Returns:

volumes in the reporting unit plus the planimetric and draped areas.

Return type:

dict

write_rasters(output_dir)

Write the DoD plus separate fill and excavation rasters.

Returns:

{name: path} of the rasters written.

Return type:

dict

run(output_dir=None)

Run the full assessment: difference, volumes and (optionally) output rasters.

Parameters:

output_dir (str) – if given, DoD/fill/excavation rasters are written there.

Returns:

the volumes() result, plus rasters when output_dir was given.

Return type:

dict