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Blotches and Burn Outs

Hi All,

Could anyone explain to me why these black blotches and white lines are appearing in my images?



These two artifacts share the same root cause. The light information is computed and stored in lightmaps with certain resolution. For example, if you use lightmap resolution of 50 it means the light is sampled 50 times per one meter (and hence 50x50 times per one square meter), so one lightmap pixel covers a 2x2 cm square on a surface and it represents the light at the center of the square. Where the 2x2 cm square is partially illuminated and partially occluded, light bleeds to the darker part or darkness bleeds to the illuminated part.

Shapespark has a post-processing pass to remove dark pixels (darkness bleeding from the occluded area to the illuminated area) after the lightmap is baked, however it didn’t remove all of the dark pixels in your scene. Your scene has bright illumination, so the default threshold for detecting dark pixels - the Flood dark limit setting in the Bake tab is too low. Increase it to 0.4 (or perhaps even more) and run post-processing using the Post-process button (scene rebake is not necessary, post-processing runs on existing lightmaps).

To remove the bright pixels (light bleeding from bright area to darker area) add a plane closing your bulidng from the bottom to block the internal walls from receiving intensive sky light.

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That’s excellent Wojtek, I understand now.