Adjusting the accuracy of the lights.

There are many ways to adjust the lights accuracy: Add more photons to the scene, turn up the Global Illumination Accuracy variable, adjust the radius, turn on Final Gathering, turn up the photon depth, etc…

First we need to turn on Final Gathering.

Because Final Gathering slows your render down, you might want to turn off the Anti-aliasing during this part of the tutorial. (Until you get to the final render)

1. Click the Render Settings button in the Photon Director
2. Click the check box next to Final Gathering in the middle of the dialog box.
3. Set the Accuracy under Final Gathering to 100
4. Click the check boxes for Minimum and Maximum Radius
5. Set the Minimum Radius to 0.5
6. Set the Maximum Radius to 12.

Render your image
It should look like this:

It looks much better. (Except for the artifacts on the walls)

To get rid of the artifacts on the walls, turn up the Accuracy variable under Final Gathering heading to a higher number.
Try 500. The higher you go the nicer it will look. (and the longer it will take to render)

With an Accuracy setting of 500 your image should look like this:

Click here for a larger version of this image.

 

Saving the Photon Map

Once you are satisfied with the image you will need to uncheck the Rebuild Photon Map option in the General Rendering Settings dialog box. Use this option in conjunction with a named Photon Map, which lets you save the Photon Map to a specific file. This will speed up your rendering, since Mental Ray will not have to calculate the dispersal of photons from that point on. If you edit your Photon Director settings you will have to check the Rebuild Photon Map box to rebuild a new map that reflects your changes. Once you have rendered again you can uncheck this option.

If you edit your Photon Director settings you will have to check the Rebuild Photon Map box to rebuild a new map that reflects your changes. Once you have rendered again you can uncheck this option.

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