Caustics are concentrations of transmitted or reflected light. If you have ever burnt paper with a magnifying glass, you already know what caustics are.
We will see how to make caustics in Strata 3D and have a look at the different render settings.
We will restrict this discussion to caustics created using spot or point lights, using the photon mapping settings in the renderer.
Transparent objects exhibit transmission and reflection caustics
Non-transparent objects only exhibit reflection caustics.
To render caustics we need two conditions:
- That at least one of our lights has Photons active
- That the render takes photons into account.
Object Properties Palette of a light with Photons Enabled
To render caustics we can use the Photon reder presets.
If we want more control, we can manually activate photons in the Lighting drawer of the Render Dialog box.
Some parameters that affect the behavior of caustics are:
Lights
Intensity, Falloff type and distance all affect caustics. All these variables affect the final light intensity when calculating caustics.
Total Falloff distance=200
Falloff=500
Render settings
Render settings control the appearance of the caustics in a render (and render times).
Photons per light
Photons per light determines how fine our caustics are. The more photons, the finer the caustics, the slower the render.
Some examples:
1 million Photons per light
2 million Photons per light
4 million Photons per light
16 million Photons per light
Depending on the scene, we may need more or less photons per light.
16 million Photons per light is not quite enough
64 million Photons yield a much nicer result
Photons per Estimate
This estimate parameter controls how fine the sampling is.
20 samples
100 samples
1200 estimates
There is a noticeable difference between 20 and 100, but not much between 100 and 1200.
Estimate search distance
Defines the distance –in model units– to search for photons that could affect the lighting for a given pixel.
Low values yield grainy caustics.Valores muy bajos generan causticas granulosas. En general, es mejor no tocar este parámetro.
Grainy caustics with a 0.1 in. search distance
Caustics Brightness
Controls the brightness of the caustics (applause).
All these examples are done with a brightness of 1.0. Below examples with different brightness values.
Brightness of 0.5
Brightness = 2.0
These examples show the basics of rendering caustics. Please share the results you get.
