Diagnostic Histograms

Terrain Maker writes a few histograms that make it possible to check a render against the numbers behind it, without opening Blender.

Score histograms

generate_score_histogram() plots raw scores next to the same scores after the transform that maps them onto the colormap (normalization, optional stretch, gamma), with bars colored by the colormap itself. Pass title to say which scores are shown.

examples/detroit_combined_render.py writes two, both through the same normalization as the rendered colors:

File

Shows

histograms/scores_before_masking.png

Base scores before lakes are blanked and near-zero scores are floored

histograms/scores_as_rendered.png

Base scores exactly as colored in the render

Comparing the two shows what lake masking and the score floor changed.

Render histograms

After a render, the combined render also writes, next to the image:

  • <image>_histogram.png: RGB channel histograms (generate_rgb_histogram())

  • <image>_luminance.png: luminance histogram (generate_luminance_histogram())

These check color balance, exposure and clipping, which matters most for print output.

API reference

See the diagnostics module reference.