Fog experiment and workflow
Posted: Sun Mar 24, 2013 11:01 pm
Not meant to be "art" - just a test with the ArchiCAD plugin.
A few points about fog.
1) Turn off autofocus and set the focus distance before adding your volumetric cube.
2) Camera must be outside the cube - so place the cube and use the camera fov to get the sizing of the image right
3) Cube seems to work slightly better than a sphere
4) Cube does NOT need normals pointing inwards
5) Cube material is specular, reflection 0, index 1, smooth disabled, roughness 0, fake_shadows enabled, medium scattering (scattering 1, absorption 0, phase 0.5, scale 0.01-.2 depending on your scene scale).
6) Directly lighting is easiest to setup, but PT works better. For PT your scattering scale will be higher than with DL.
7) The size of the cube is critical. If you have a room with a window where you want the effect, the cube should fill the room (except the camera position), but should not go outside the room - since then it will just be diluting the lightsource. For exterior scenes, the cube will be much biggger - but the edge of the cube should not go all the way to the camera, since then there will be fog whitening the shadows too much.
8) Use post-processing to adjust the intensity - I lowered the gamma and increased intensity of the image below.
9) The image below has some bright dust particles - which I like - so keep caustic blur at minimum for this. In practice you will probably want some blur on these, which you get through caustic_blur.
Paul
A few points about fog.
1) Turn off autofocus and set the focus distance before adding your volumetric cube.
2) Camera must be outside the cube - so place the cube and use the camera fov to get the sizing of the image right
3) Cube seems to work slightly better than a sphere
4) Cube does NOT need normals pointing inwards
5) Cube material is specular, reflection 0, index 1, smooth disabled, roughness 0, fake_shadows enabled, medium scattering (scattering 1, absorption 0, phase 0.5, scale 0.01-.2 depending on your scene scale).
6) Directly lighting is easiest to setup, but PT works better. For PT your scattering scale will be higher than with DL.
7) The size of the cube is critical. If you have a room with a window where you want the effect, the cube should fill the room (except the camera position), but should not go outside the room - since then it will just be diluting the lightsource. For exterior scenes, the cube will be much biggger - but the edge of the cube should not go all the way to the camera, since then there will be fog whitening the shadows too much.
8) Use post-processing to adjust the intensity - I lowered the gamma and increased intensity of the image below.
9) The image below has some bright dust particles - which I like - so keep caustic blur at minimum for this. In practice you will probably want some blur on these, which you get through caustic_blur.
Paul