Posted by MaxStation, 25 February 2011 12:00 am
When you render at high resolution you don't need to render the final gather map at the same resolution. By first rendering the final gather map at a lower resolution and then rendering the scene at the required resolution with the final gather map you've rendered earlier you can reduce the render time significantly and still get a good end result.
Once you're ready to render the scene first lower the output resolution (as an example 1024x1024 instead of 4096x4096).
Then set the final gather map file name: go to the indirect illumination tab of render setup dialog, scroll down to the Reuse (FG and GI Disk Caching) and click on the "..." before the filename field above the 'Generate Final Gather Map File Now' button.
And render the final gather map by clicking on the 'Generate Final Gather Map File Now' button. This should be something like 16 times faster than doing the final gather at full resolution.
Once that's done change the Final Gather Map to 'Read FG Points Only from Existing Map Files' so the subsequent render will use the file we've just rendered.
Go back to the Common tab, set the render resolution to 4096x4096 and do the render. It will now skip computing the final gather mapand use the file we created earlier.
For more details on reusing final gather see the online help: Autodesk 3ds Max Help > Rendering > Renderers > mental ray Renderer > mental ray Renderer Interface > Indirect Illumination Panel > Reuse (FG and GI Caching) Rollout (mental ray Renderer).
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