You can find the Max Ray Depth parameter in Render Settings > Corona > Performance Settings. It governs both the maximum number of GI bounces and the maximum number of allowed reflections/refractions. The default value of 25 means that for each ray, a maximum of 25 intersections is allowed - be it diffuse bounces, refractions, or reflections. For a solid glass object, one intersection takes place when the ray hits its surface, and the second one when it exits the object. Increasing Max Ray Depth to a higher value than the default, usually brings no visual benefits.

 

Examples

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1.1. Crystal - MRD = 25 (default value)

 

 

1.2. Crystal - MRD = 1 

 

 

1.3. Crystal - MRD = 2 

 

 

1.4. Crystal - MRD = 3 

 

 

1.5. Crystal - MRD = 100 

 

 

2.1. Two mirrors facing each other, camera between them - MRD = 25 (default value) 

 

 

2.2. Two mirrors - MRD = 1 

 

 

2.3. Two mirrors - MRD = 2 

 

 

2.4. Two mirrors - MRD = 3 

 

 

2.5. Two mirrors - MRD = 100 

 

 

3.1. Room - MRD = 25 (default value) 

 

 

3.2. Room - MRD = 1 

 

 

3.3. Room - MRD = 2 

 

 

3.4. Room - MRD = 3 

 

 

3.5. Room - MRD = 100