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What's the trick to rendering with saved solutions?

Michael J. Brown

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Okay...I've tried every combination and option I think would logically work, but still can't seem to get my image to render using saved irradiance and light cache maps.


Here's what I THINK should be happening. When saved solutions are used for these two, my render should skip the numerous prepasses and skip the light cache phase - just jumping straight into the rendered buckets - right? (assuming I've already rendered the view at least once to save the solutions)


Here's what I've done in the past: 1st render (at low resolution) Set the Modes for both irradiance and light cache to Single Frame; check Don't Delete and Auto Save (on render end); click Save to file next to the mode to give the light cache / irradiance map names; leave Swith To Saved Map unchecked; then RENDER. 2nd render (at desired resolution) switch Mode of both to From File; RENDER. But it still runs through all the prepasses and light cache generation.


Can someone please walk me through the correct process? Because I feel like the Wizard of Oz behind the curtain trying to figure out which of these majic buttons I need to push to get this to work. This is one part of the Vray interface that I wish were simpler.




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You need to use the "save" option to the right of the singe frame option in the irradiance map drop down. Leave the light cache as single frame with no saving. It will be added to the saved irradiance map.


When you want to use the saved vrmap file, do a from file in the irradiance map drop down and turn the secondary bounce (light cache) off.

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hi Typically I do this as a three pass process.


First I set both indirect illumination modes to LightCache, primary and secondary, then I do my light cache calc, usually pretty high around the 2000. I only do this on the first frame of the animation and I have the light cache set to 'Fly-through', once that has finished I 'save to file', making sure of course to have don't delete ticked before I do the pre calc. then I load that file into memory with the 'from file' mode. Switch off 'don't render final image' in global settings.


I change the irrmap to the primary indirect illumination then, I set the range of the animation frames, and choose to calc the irr map for every nth frame, this number depends on the speed of the camera movement. Slow movement you can get away with a higher nth number. I generally reset the map before I start this clac to clear the cache of unnecessary data. Then in 'multiframe incremental' I do the calc and hit 'save to file' once this has finished.


Then I load this file into memory using the 'from file' mode.


I go to global settings, untick the 'render final image box', change my nth frame back to every 1 frame, and hit go.


You should now have you light cache and irrapmap precalced and should only see the buckets rendering the final image.


Hope this helps. I think you were on the right lines, but you might have missed setting everything to light cache mode to start with? Though I'm not sure if that is essential, just the way I have always done it.

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We deal with this issue a *lot* at ResPower.


Here's a tutorial we have for doing this:




And here's one for generating them on our render farm, as opposed to on your computer. Unfortunately, it's not a parallel process yet, but it at least frees up your computer :-)




-- Early Ehlinger, President, ResPower, Inc.

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