There is some problem with VLM Vol.LightMap for dynamic shadowing.
Vol Cells are placed ( i suppose ) starting from 0,0,0 where is placed the centre of the cell.
So - in many cases - when our scene begins at Z=0 this first cell row (z=0) is taking lights for computing form interior and exterior. In causes that his Z0 Cell gives additional bad light at the bottom of the scene. Solution that I use now is add “envelope - exterior walls” walls that makes some border between exterior and interior walls (surrounds interior). In this space bewteen is darkness so with small VLM Cells (i.e. with size of 16 ) the dynamic light is ok. But it consumes more memory.
I have two ideas how to improve whole VLM Vol LM system:
- Add offset to Cells Grid to have ability to move all grid in demanded direction to avoid that some cells are taking unexpected light from exterior
- Develop VLM Importance Volume system ( like for Lightmass importance volume ) to set the VLM grid locally with demanded size ( i.e. scene has size 200 , but local VLM grid that surrounds i.e whole interior has 16 for better dynamic shadow resolution ) - this gives
This image shows the problem: