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Tuning caustic settings

From: Lighting and Rendering with mental ray in Maya

Video: Tuning caustic settings

This movie is going to discuss some of the ways in which we can improve the look of caustic light patterns, and we have a caustic photon-emitting light set up in this scene. But as you can see, this light pattern is very blown out, and we don't have very much definition here. Let's look at some of the ways that we can improve this. I'll store this render and minimize the render view and spotLight2 is my caustic emitting light. So, the first thing I'm going to do is go to the Render Settings and under Indirect Lighting, I'm going to go to Caustics, and this is a situation in which a lower Accuracy is actually going to give us a better result, more definition to our caustic lights.

Tuning caustic settings

This movie is going to discuss some of the ways in which we can improve the look of caustic light patterns, and we have a caustic photon-emitting light set up in this scene. But as you can see, this light pattern is very blown out, and we don't have very much definition here. Let's look at some of the ways that we can improve this. I'll store this render and minimize the render view and spotLight2 is my caustic emitting light. So, the first thing I'm going to do is go to the Render Settings and under Indirect Lighting, I'm going to go to Caustics, and this is a situation in which a lower Accuracy is actually going to give us a better result, more definition to our caustic lights.

So, I'm going to set this down to about 15. The other setting I want to change is the Radius. When Radius is set to 0, you're basically telling mental ray to figure out the radius for itself. In other words, 0 radius means mental ray, you decide based on the scene, based on the way the lights are set up, and what radius works best in the scene. So in this case, by raising this to 2, I'm taking control of the radius and giving it an exact size for mental ray to use. I'm going to minimize this and create another test render and see what we get.

So now you can see we're actually getting more definition, we could see individual photons a little bit easier. It's a bit spread out and fairly blown out right here. So, another thing that I can do is actually change some of the qualities of the transparent shader that's applied to the vase. When I created the shader, all I did was apply a standard blinn, and I have Transparency set all the way up to White, so this is 100% transparent. And down here in the Raytrace Options, I have a Refractive Index of 1.2.

Refractions are activated, and this is a setting of 1.2, which essentially is a good simulation, a good value to simulate glass. But if I change this, you're going to see it has a huge impact on the way the caustics looks, and we're going to set this to 0.9 and create a test render. You can see that that's actually changed the way this looks a lot. This is spread out more of an angle this way and around the vase here. I'm going to keep this image, and then I'm going to choose this light again, and I'm turning on Wireframe on Shaded so that I can see where the vase actually is, and I'm going to choose Panels > Look Through Selected Camera.

I think if I pull this out just a little bit - I'm just zooming out and then in the Light settings, I'm going to decrease the cone angle, so that it's a little bit tighter around the vase, switch back to the Perspective view and do another render, and you can see now that I'm getting something that I like a little bit better. This is looking a little bit more realistic to me. There is a danger though, to changing the refractive index to the shader, in that it's going to change the caustic light pattern, but it's also going to change the way the glass looks.

So, if I go back here, you can see this is what a refractive index of 1.2 looks like; it looks a lot like thick glass. And by changing it down to 0.9, I'm getting something that looks a little bit different. So, when tuning this effect, it's going to be a question of balance: how much you want to change the look of the glass to get a better caustic effect.

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This video is part of

Image for Lighting and Rendering with mental ray in Maya
Lighting and Rendering with mental ray in Maya

59 video lessons · 7821 viewers

Eric Keller
Author

 
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  1. 3m 46s
    1. Welcome
      1m 32s
    2. Using the exercise files
      2m 14s
  2. 19m 8s
    1. What is a CG light?
      1m 22s
    2. Types of CG lights
      10m 55s
    3. Direct lighting
      4m 48s
    4. Indirect lighting
      2m 3s
  3. 53m 20s
    1. Decay rate
      6m 30s
    2. Previewing lighting and shadows
      2m 37s
    3. Creating depth map shadows
      1m 57s
    4. Troubleshooting depth map shadows
      2m 38s
    5. Shadow map overrides
      5m 30s
    6. Using the shadow map camera
      5m 31s
    7. Saving and reusing shadow maps
      2m 48s
    8. Creating raytraced shadows
      1m 56s
    9. Adding softness to raytraced shadows
      3m 42s
    10. Creating area light shadows
      5m 11s
    11. Sample: mental ray area light
      4m 23s
    12. Setting area light visibility
      8m 7s
    13. Creating soft shadows with spot lights
      2m 30s
  4. 43m 35s
    1. Setting global illumination for interiors
      2m 33s
    2. Tuning global illumination
      5m 56s
    3. Global illumination photons
      1m 12s
    4. Activating caustic light effects
      3m 28s
    5. Tuning caustic settings
      3m 35s
    6. Setting caustic light effects on metal
      2m 35s
    7. Using final gathering for indirect lighting
      2m 9s
    8. Tuning final gathering
      4m 2s
    9. Reusing final gathering maps
      3m 21s
    10. Adding light with shaders
      5m 27s
    11. Creating final gathering maps for animation
      4m 26s
    12. Combining final gathering with global illumination
      4m 51s
  5. 1h 2m
    1. Activating the Physical Sun and Sky network
      2m 33s
    2. Tuning the Physical Sun and Sky settings
      7m 18s
    3. Applying physical light shaders
      8m 54s
    4. Applying image-based lighting
      8m 57s
    5. Tone mapping
      6m 23s
    6. Applying portal light shaders
      7m 45s
    7. Creating light beams with participating media
      10m 9s
    8. Adding depth of field with the Bokeh lens shader
      10m 39s
  6. 48m 21s
    1. Introducing render layers
      6m 13s
    2. Creating render layers
      4m 28s
    3. Splitting a scene into render layers
      15m 36s
    4. Applying render layer presets
      7m 47s
    5. Setting render layer overrides
      7m 7s
    6. Creating render layer composites
      3m 52s
    7. Organizing renders with tokens
      3m 18s
  7. 42m 24s
    1. Introducing render passes
      2m 56s
    2. Comparing render passes and render layers
      6m 44s
    3. Editing render passes
      10m 41s
    4. Using appropriate materials
      5m 51s
    5. Batch-rendering passes
      5m 56s
    6. Compositing in After Effects
      6m 41s
    7. Rendering the EXR image format
      3m 35s
  8. 23m 3s
    1. Anti-Aliasing Quality
      6m 44s
    2. Setting color profiles
      2m 53s
    3. Diagnosing raytracing
      5m 7s
    4. Adjusting motion blur
      6m 57s
    5. Finding mental ray help
      1m 22s
  9. 21s
    1. Goodbye
      21s

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