BUILD_HILLSHADE_DSM

Generates a hillshade GeoTIFF from a LAS/LAZ point cloud by first rasterizing the points into a Digital Surface Model (DSM) and then applying GDAL's hillshade algorithm. The output is a single-band GeoTIFF with shaded-relief intensity values (0–255).

The rasterization uses PDAL's writers.gdal to aggregate point heights at a configurable resolution. The hillshade is computed with fixed cartographic defaults — azimuth 315° (north-west sun), altitude 45° — producing a standard terrain illumination effect. Nodata cells are marked as -9999.

Typical use: generating 2D terrain visualization layers from airborne LiDAR or MBES point clouds for web mapping, reporting, or QA overlays.

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Contract

Type	BUILD_HILLSHADE_DSM
Accepts	input_las: las
Produces	hillshade_dsm: tif
Params	resolution (opt), output_type (opt), z_factor (opt)

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Inputs

Slot	Type	Description
input_las	las	Source point cloud dataset

Outputs

Slot	Type	Description
hillshade_dsm	tif	Single-band hillshade GeoTIFF

Parameters

All parameters are optional. Omitting them applies the defaults shown below.

Name	Type	Default	Description
resolution	number	1	Raster cell size in CRS units (e.g. 1 → 1 m/px for metric CRS)
output_type	string	"max"	Height aggregation per cell: max, min, mean, idw, count, stdev, or all
z_factor	number	1	Vertical exaggeration for the hillshade. Values > 1 emphasize relief

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What it does internally

1. Downloads the input LAS from MinIO
2. Builds a PDAL pipeline using readers.las → writers.gdal with the configured resolution and output_type, writing raw_dsm.tif
3. Runs gdal_edit.py -a_nodata -9999 to stamp the nodata value on the raw DSM
4. Runs gdaldem hillshade with z_factor, azimuth=315, altitude=45 — producing hillshade_dsm.tif
5. Runs gdalinfo -stats on the output to capture raster metadata into the artifact record
6. Uploads hillshade_dsm.tif to MinIO and returns the artifact

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Recipe usage

{
  "id": "build_hillshade_dsm",
  "type": "BUILD_HILLSHADE_DSM",
  "inputs":  { "input_las": "job:input_las" },
  "outputs": { "hillshade_dsm": "step:build_hillshade_dsm.hillshade_dsm" }
}

With explicit params (all optional):

"params": {
  "build_hillshade_dsm": {
    "resolution": 1,
    "output_type": "max",
    "z_factor": 1
  }
}

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Artifact storage path

artifacts/job_{id}/build_hillshade_dsm/hillshade_dsm.tif

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Related executors

• COLORIZE_AS_DEM — also derives a DEM from points, but produces a colorized point cloud rather than a 2D raster