Controlled Raster Recipes

ras2cng raster-calculate creates analysis rasters from aligned numeric COGs. It accepts only named recipes with typed inputs and parameters; arbitrary Python, GDAL expressions, and user-supplied scripts are not evaluated.

Available Recipes

Recipe	Required inputs	Output
compare_wse	baseline, comparison WSE	Comparison minus baseline WSE
compare_depth	baseline, comparison depth	Comparison minus baseline depth
compare_velocity	baseline, comparison velocity	Comparison minus baseline velocity
depth_velocity	Synchronized depth, velocity	Depth multiplied by velocity
depth_velocity_squared	Synchronized depth, velocity	Depth multiplied by velocity squared
hazard_class	Synchronized depth, velocity	AIDR 2017 H1-H6 hazard class
inundation_threshold	depth	Below/at-or-above threshold mask
terrain_mod_delta	original, modified terrain	Modified minus original elevation

Depth-velocity and hazard recipes require the same explicit profile or timestep for both inputs. Independent Max surfaces are rejected because their maxima can occur at different times. Input rasters must have exactly matching CRS, transform, dimensions, and pixel grid. Compatible US customary and metric units are converted before calculation.

ras2cng raster-calculate depth_velocity output/dv.cog.tif \
  --input depth=maps/Depth_01JAN2026_120000.cog.tif \
  --input velocity=maps/Velocity_01JAN2026_120000.cog.tif \
  --input-unit depth=ft --input-unit velocity=ft/s \
  --plan p03 --profile "01JAN2026 12:00:00"

Processing is windowed and writes a staged tiled GeoTIFF before atomically replacing the final COG. Nodata remains transparent. The adjacent .provenance.json records the recipe version, input roles, units, parameters, plan/profile, and output metadata. Full SHA-256 hashes are opt-in because hashing adds another complete read of every large raster.

Viewer Publication

Publish a recipe output under its plan's Calculated Layers branch:

ras2cng maplibre-calculated-map output/dv.cog.tif VIEWER_DIR \
  --plan p03 --recipe depth_velocity \
  --profile "01JAN2026 12:00:00" --geometry g03 \
  --source-cog ../archive/calculated/p03/dv.cog.tif

The numeric COG remains authoritative. The PMTiles derivative is a fast display layer. Calculated-layer provenance distinguishes ras2cng arithmetic from the RASMapper/RasProcess interpolation used to create its source surfaces. Hazard and threshold outputs use fixed categorical legends and cannot use a current-view stretch.