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View Full Version : How do I optimize a scene for rendering with FPrime ?



OlaHaldor
02-22-2010, 06:42 AM
I have a huge interest for interior and architecture, and I'd like to get into this part of the 3D circus. I've got a floor plan from a friend. She's working at a kitchen interior design company, and gave me some good plans and information about scale, material etc.

So I've modeled a kitchen with somewhat ok detailing, it's fully textured with wood and stone textures, and I've tried some rendering. I've placed a few sphere lights for interior lighting and a distant light for the sun to peek through the windows. All along with this I'm using Monte Carlo GI in FPrime. The preview looks good - but it's taking ages to calculate.

I even put it to render last week and let it render three frames with different angles inside the room. In a total of 16 hours, it had done some fundamental rendering, but was no way near as clean and nice as renders I've seen elsewhere.

I guess the problem is the lighting, but I'm open to change other parts of the scene as well. Unfortunately I don't have the renders I did last week on this computer, but I can add these when I'm back at work tomorrow.


Meanwhile, I'd like to know your thoughts on this. I brought the dongle home with me so I can take your ideas and thoughts into practical examples.

3dworks
02-22-2010, 07:52 AM
without screenshots it will be difficult to say anything less general, but here some points from my experience:

* be sure to check the tutorial on worley's site about light quality's settings, it's fundamental for optimizing fprime's render speed.
* in render globals, set reflections to off if you don't need them (normally you don't with architectural glass).
* use 'old school' layered surface materials instead of material nodes, they render much faster. use gradients for realistic reflections/ transparency settings.
* check your render globals settings for the ray recursion limit: 16 bounces, the default setting is not needed normally, set it lower, to 10 for example, and check if all your reflections/refractions are there. set it lower until you see that one reflection/refraction layer is missing.
* in fprime master, rarely more than 3 bounces are needed. a trick is to set the radiosity intensity setting higher, for example to 150-200%
* check for each reflective surface if reflection blurring is enabled and really necessary.
* try to use area lights as much as possible, they are the best compromise between speed and quality. most other 'realistic' light types, like IES, spherical, etc need relatively longer to render.

optional: try kray (www.kraytracing.com) - awesome speed with high quality. on the downside, it requires some dedication for the settings and it is not fully surfacing compatible with fprime.

cheers

markus

OlaHaldor
02-22-2010, 08:31 AM
Thanks a million! Really good points there, Markus. I'll certainly dive into your tips.

I've been drooling for Kray for about a year, unfortunately it's not available at the time due to a failure at PayPal.

Danner
02-22-2010, 01:36 PM
now that I got a good grasp on Lightwave's radiosity I never use fprime to render, it's invaluable to set up lights and textures, but lightwave is so much faster with the right settings. Fprime is faster for reflections refractions and transparency, but unless your scene is full of those LW is faster.

OlaHaldor
02-23-2010, 01:48 AM
As promised, here's a few images for you from the rendering that it had worked on for about 16 hours. I forgot my dongle at home, so I can't open the FPrime master window. But I believe light quality was set at 1, radiosity 100%, and it had.. I don't know.. tens of anti aliasing passes.

I'll take this model and scene back home with me to see if my Quad Core can do a better job than my 2xQuad Mac Pro. :D

3dworks
02-23-2010, 02:02 AM
As promised, here's a few images for you from the rendering that it had worked on for about 16 hours. I forgot my dongle at home, so I can't open the FPrime master window. But I believe light quality was set at 1, radiosity 100%, and it had.. I don't know.. tens of anti aliasing passes.

I'll take this model and scene back home with me to see if my Quad Core can do a better job than my 2xQuad Mac Pro. :D

honestly, fprime is brilliant and still much faster than LW's renderer with very complex scenes (with lots of millions of polys), especially when you add 'ton's' of area lights and also need soft refractions and reflections.

but if you are using LW 9.6.x, this scene doesn't look too complex for the native LW GI engine... give it a try and you'll see a noiseless result *much* faster! orient yourself with this excellent guide: http://www.except.nl/lightwave/RadiosityGuide96/index.htm and you will see that it's not that difficult to setup.

unfortunately, there's also a huge speed penality on multicore macs under OSX with current LW and fprime, only 2 cores are supported at all - see here http://www.worley.com/E/fprime_support.html - it should be solved with LW 9.6.1 which now is on beta, but we are all still anxiously waiting for steve worley's fix... (no idea when and if this might come).

cheers

markus

pooby
02-23-2010, 02:45 AM
Fprime is not really appropriate for interior GI.
When geometry is heavily occluded from a light source, like an interior room from the sun, Fprime's render will be noisy and take a very long time to resolve.
This is because Fprime is taking no shortcuts and calculating each pixel individually and accurately. The amount of iterations needed to make each pixel blend in with its neighbours is huge. Hence the time.
Interpolated renderers will get around this by doing a pre-process, sampling areas wider apart and merging the results together. It is less accurate, but that doesn't really matter and it will look noiseless. (although it can look 'blobby' where the areas merge if you aren't careful)

Fprime is great for Gi on deforming geometry (where interpolated fails currently) and on geometry more open to light sources, but LW's interpolated GI will give much cleaner results here on your example

ingo
02-23-2010, 03:25 AM
..... I've placed a few sphere lights for interior lighting and a distant light for the sun to peek through the windows. ....

Thats your main problem, sphere lights look nice but are slow. Just replace them with normal area lights in the windows, that should render way faster.

At the moment i do a test rendering an interior with sphere instead of area lights, instead of 2 hours it renders in 20 hours (same goes for dponts face-lights).

ingo
02-23-2010, 03:30 AM
....
* in fprime master, rarely more than 3 bounces are needed. a trick is to set the radiosity intensity setting higher, for example to 150-200%...

i would try to avoid setting render intensity higher. If you render with 200 % it needs twice the rendertime compared to 100 %, same as if you use 2 bounces instead of 1. But 2 bounces give a smoother light than 200 %.

Usually my interiors have 2 bounces and 100 % intensity and 5-10 % ambient light, to get more light in i add distant lights without shadow to brighten up dark areas.