Why Mesh lights(or all of arnold lights) cannot render physical caustics?

[3156657639]

  

The essence of the problem is why Mesh lights cannot produce shadows.

In some scenes, I don't want to use massive self-illumination lighting to render glass, but I also need the effect of physical lighting,so hy Mesh lights(or all of arnold lights) cannot render physical caustics?

1:(Mesh light is not generated by ray tracing, but based on integral algorithm)

2:（Can Arnold's transparent material give shadows to Mesh lights?I don't want to cheat, I want to use pure physics）

[3156657639]

I use Arnold 4.5.0（Arnold 7.1.4.0)

This problem also exists in previous versions, not only in Cinema4D, but also in other software

[lee_griggs]

1. Arnold doesn't produce true caustics.

2. Mesh lights cast shadows. Reduce the transmission_weight to 0.9. 1 is 100% transparent.

[3156657639]

Is there any way to use Mesh light to make completely transparent glass produce pure black shadow ?I want GI to generate caustics in the shadow, which is correct in physical expression

[lee_griggs]

Arnold doesn't render true caustics. Maybe you could fake something with the ray_switch shader or follow this tutorial for fake caustics.