Shade
Render a DATA_FIELD as a directional hillshade image using Lambertian reflectance. Surface normals are estimated from Sobel gradients, and shading intensity is computed from the dot product with a configurable light direction. Equivalent to Gwyddion's shade.c module.
Inputs
| Name |
Type |
Required |
Description |
| field |
DATA_FIELD |
Yes |
Input surface field to shade |
Outputs
| Name |
Type |
Description |
| shaded |
DATA_FIELD |
Shaded surface rendering |
Controls
| Name |
Type |
Default |
Description |
| azimuth |
FLOAT |
0.0 |
Light direction in degrees: 0 = north, 90 = east, 180 = south, 270 = west (0-360) |
| elevation |
FLOAT |
45.0 |
Light elevation angle above the horizon in degrees (0-90) |
| blend |
FLOAT |
0.5 |
Blend factor between original data and shading: 0.0 = original data only, 1.0 = shading only (0.0-1.0) |
Notes
- Surface normals are computed using Sobel gradient operators, providing good noise resilience compared to simple finite differences.
- An azimuth of 315° (northwest illumination) is a common choice that produces natural-looking topographic shading.
- Elevation of 90° gives flat, uniform lighting; lower angles emphasize surface texture and fine features.
- The blend parameter controls how much shading modulates the original height data. Use 0.5 for a balanced view, or 1.0 for pure shaded relief.
