When attempting to render an animation with the GI Mode set to “IR+QMC Net Render” every frame render is preceded by around 90 seconds of calculation accompanied by a message saying “Updating Records for Diffuse Depth #1.” This happens whenever I try to render a sequence of frames on my Mac Pro. When doing a NET render it’s apparent that the client machines are doing similar calculations based on the time it takes to render each frame. This does not happen when I render a single frame; the frame starts rendering immediately.
When rendering a frame range, after that 90 second “updating records” calculation it renders the frame, which for this scene at 1920x1080 takes an additional 4-6 minutes on my fastest workstation. Then it spends another 90 seconds updating those records, and then renders the next frame. And so on. This is all despite running a pre-pass on the IR cache, locking it in, and making sure the .gi file was visible to the scene.
That would be an additional 10.5 hours of “updating records” over the course of my 420-frame animation.
What the what?
As I related in my earlier thread dealing with my attempts to create a camera animation of a room lit with GI, I had to resort to workarounds like baking all of the objects in the scene because my attempts to NET Render the scene resulted in obvious jumps between the ranges of frames rendered on the various client computers; it appeared the client computers weren’t seeing the illumination files, even though they were visible on the server. So after around 8 hours of work I was able to get everything baked adequately for a final render, the result being 1920x1080 frames that renders in under 10 seconds each on a 12 core Mac Pro.
But that was all a workaround. I really want to just be able to render the scene as-is without all that baking effort. I’d rather have my computers churn away hours longer on the final render than lose all that billable time setting up all of the objects in my scene to bake in the illumination.
After a lot of research I finally found why the client computers weren’t seeing the IR Cache files on the NET Render server. When I save a project with assets for NET Render I add “NET” to the name of the project, and so the project name no longer matched the .gi and .gir file names. Once I made sure those pre-passed files had the same name the client machines saw the cache and I got consistent frames. It would be swell if the documentation made this clear; I had to find that tidbit of pertinent information on an old CGTalk forum. Thank you, Google.
But then I ran up against this “Updating Records” issue, making it impractical to render an unbaked version of the scene using a NET Render of our three workstations. That issue added too much overhead.
I was about to tear my hair out, but on a hunch I changed the GI mode to IR+QMC (Camera Animation). I ran another IR Cache pre-pass at half-size with a 30-frame frame step, then launched a Net Render. Lo and behold, it appears to be working. The frames look the way I want (light leaks and all) and there are no jumps between frames rendered on the different machines (all Mac Pros).
So I guess I’d like to know what the GI Mode for the Net Render is doing that requires all of that additional calculation, even when I pre-pass the cache for EVERY frame and lock it in. Thinking the “updating records” issue was happening because I was skipping frames in the pre-pass I tried calculating the cache for a 20-frame sequence with a frame step of 1. It calculated the IR cache, but also spent a huge chunk of time updating records for diffuse depth. But all of those additional calculations did nothing to the .gi file, and when I test rendered that 20 frame excerpt it ran the “updating records” calculations all over again on each frame.
Again, what the what?
And does enabling Radiosity Maps do anything to speed up calculations or improve quality in this situation? I forgot to enable them when I ran the cache pre-pass for this current render (which will probably take 16 hours on our three systems), and the frames look fine.
I’m still itching to see a tutorial on Radiosity Maps, when to use them and what their benefits are.
Thank you.
Shawn Marshall
Marshall Arts Motion Graphics