View Full Version : quick best advice for baking radiosity?

02-21-2016, 11:30 PM
I am rendering out some scenes where only the camera moves. The lighting and objects don't change, so what is the best option for radiosity. I'm happy with the GI look and the settings I have, it's just this step of setting up the render so I can walk away from it that I'm not confident with, and I need to get this sequence finished and just don't have the time to go reading up on it again.


I am currently rendering but I can see that the time per frame is increasing, I've forgotten which option I checked.

I think I just want to bake the radiosity into a cache, but only calculate it on one or two frames. Does anyone know the steps, is it bake frames or bake scene? Do I move to a frame, hit bake frame and then move to another frame and repeat to build up the radiosity solution, and then set the cache to Locked?

02-22-2016, 12:33 AM
sometimes what I do is a really big first render, I try to get everything showing on camera that will be in the animation, set to always and render, then set to locked and render the animation after setting the camera back, you can render a series of frames to build up more of a radiosity solution, however if se to animation or what ever I have seen the cache eat away ram very quickly so be care full, again it is one of those things that depends on your surfaces and lighting so there is no set in stone solution. to get flicker free rendering the first frame is a good option, but you tend to find the more distant from the camera the objects are the bigger splotches will be (that's why I do an extra big frame to try and force the splotches smaller)

02-22-2016, 02:04 AM
With your one big frame solution, does it help to put other cameras in there to cover a few more angles? But if so how do you render a frame, do you render a single frame of each of those cameras.

02-22-2016, 02:09 AM
If the camera moves then you want to bake the scene - baking a frame will just bake that frame you're on and add it to the radiosity cache. The process I use is to clear the cache, making sure you start from scratch as you may have unwanted leftover radiosity data cached. Then set the preprocess to always ( I use automtatic but I'm unsure of the difference - I assume automatic will only cache a frame it knows to have changed). Set the Frame Steps to something sensible - if there's a lot of movement with new geometry being exposed to the camera quickly, then you need a tighter number of steps, every 2-5 frames. If the camera is fairly slow then you can up that to 10-20 - it really does depend. Once the cache is baked, change the Pre Process to Locked and render the scene out.

If you choose quite a loose spread of cached frames and you find you have problems later, you can always add to the cache. For example, first time around you might decide to bake every tenth frame, so 0,10,20,30 etc you then lock the cache and do some test renders on random frames. You may find then that some geometry isn't in frame long enough to be caught on one of those frames you've cached radiosty data from (it'll look odd when rendered), so you can unlock the cache and bake a specific frame, adding it to the cache, or you can start a new sequence and add that to the cache, so 4,15,25,35 etc.

Good luck!

02-22-2016, 02:24 AM
My camera advances toward the object on a fairly linear path, not much new geometry gets exposed throughout the entire shot, I imagine that the start and end frame and a frame from the middle of the animation would expose all the geometry that the camera ever sees, would I just clear the cache, set it to Always, then bake those three frames one after the other, then lock it and render?

02-22-2016, 09:20 AM
That sounds about right. In fairness though, if there's not much new geometry getting exposed with each frame, you *might* as well do a few extra cache frames, as each frame only adds what's new to the camera, so they'll be quick anyway. But you might find that as you get closer to the object that some geometry qualifies for additional cache points as the area gets larger etc. Try the three frames and do a low res test, you can always throw extra frames into the cache afterwards.

02-22-2016, 12:28 PM
I used to render with interp MC and animated cache using 2 bounces, 1000 RPE, 100 SBR, and frame step 10, BUT due to random shading niggles here and there, unwieldy cache files, and not being able to dissolve objects out without a "pop" in shading going from 99.9999% dissolve to 100%, I have now opted for straight MC (can't be cached by nature) using 2 bounces and 4 or 5 RPE. Yes, the renders take 2 times longer (from 5 min/frm to 10 @ 720HD or from 16 to 32min @ 1080HD), but this is offset by not doing the pre-process anim cache render (typically 1 - 2 hrs for 300 - 450 frames at 720HD or 3 - 6 hrs @ 1080HD) and I no longer worry in the slightest about flicker or smudgy, splotchy, undefined occlusions, nor any issues related to objects, lights, deformations, and any other motions. I take care of the grain by using 8 samples/pixel and 32 AA passes at 0.002 threshold. This leaves a bit of grain very similar to film.

02-23-2016, 08:05 AM
Thanks for all the advice, for this situation just frame baking selected frames of the sequence produced a good result.

02-23-2016, 09:46 AM
Great to hear :thumbsup:

02-23-2016, 11:13 AM
If the only thing that is moving is the camera my basic settings and procedure for interiors is: sRGB color space, 3 bounces, 600 rpe, 400 secondary, 3 min pixel spacing, max pixel spacing 100, multiplier 100. I go higher on rpe and secondary if there is noise and up rays and lower min pixel spacing if there is a lot of fine detail.

Then I give the cache a name and a frame step of 15 (if the camera moves fast then you must lower this number) set cache to automatic, clear it, make sure "animation" is turned off in cache options, then go to the render tab, turn off reflections and refractions. Then click on "bake radiosity scene" this should take from 10 minutes to an hour depending on the scene complexity and duration. After that is done, turn reflections and refractions back on, Lock the cache, save scene and render. You'll have a clean and rock solid radiosity solution and very good render times.