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csoars
09-21-2006, 05:31 AM
See my little picture on the left - it is a render of a pile of wine glasses and a half filled bottle on a reflective table. When I first got LW it was the first thing I did (actually it was a tutorial for one glass but, as usual I got carried away)

I planned to have the camera do a sweep - about a 8 second avi.

However, to get the quality right I had to set it to pass 5 times then I rendered one frame and that took 16 hours. There is a lot of glass here and a lot of reflection but I was shocked by how long it took.

If I had let it go for the 8 second clip it would have taken 130 odd days to render.

Question - I really wanted a high quality image but is this normal?

mrunion
09-21-2006, 05:54 AM
Yup, this can be completely normal. It does depend on some of your settings, and pushing some of them around (ray recursion) may help some. But yeah, alot of glass, reflection and refraction equals mondo render times.

Bliz
09-21-2006, 06:00 AM
Put the scene in a box or room and see if that helps. All those rays are probably travelling too far into the void.

Sarford
09-21-2006, 07:13 AM
You are not using radiosity are you? That would be a total waste of time with a black background.

Part of the trick with 3D is not to make it 'mathematicaly' right but to make it 'look' right. Lots of things you can do to shave off rendering times. Look at some works of Ceasar Montero, his work looks very photorealistic yet he never uses radiosity or any other fancy stuff. Knowing what to light and how to light can save you heaps of rendertime...

Phil
09-21-2006, 07:55 AM
Check your raytrace recursion level. You might be able to dial it down without losing too much from the final image. It should help with the render time.

robewil
09-21-2006, 09:28 AM
If the camera will be in motion, it's probably not necessary to do as many passes for the moving frames. Just do the full quality render for the beginning and ending frames.

Lottmedia
09-21-2006, 09:31 AM
Is that the actual size image you rendered? ('cause it's super tiny:)) I wouldn't mind seeing a larger version. I can't see a thing in it (it's 133x100!!) let's get an idea of what you're working with :thumbsup:

Casey :cat:

toby
09-21-2006, 11:33 AM
Unless you're using Radiosity, I'm sure it's the ray recursion that's slowing things down. Try it at about 8. I've always found the default 16 to be unneccessarily high, it starts to become redundant or even too many bounces. You can try lower than 8, but the lower you go, the more reflections you lose, and transparency can become cloudy or black, so do test renders if you want to find the fastest render for the quality you want.

Exception
09-21-2006, 11:54 AM
Is this LW 9?
If so, are you using the perspective or the classic camera?
Use the perspective...
tone down ray recursions, as mentioned.
Don't use radiosity for this...

csoars
09-22-2006, 10:20 PM
Thanks guys - I will try some of these things. Sorry abotu the image size - I accidently posted my little ID image (which is the same). Here is the full image.

Colin

toby
09-23-2006, 02:31 AM
oooh...specularity... baaad.... incidence angle... gooood... a good environment for the reflections is critical. HDRs work great for this.
notice the way that the glasses, particularly the one on it's side, look like they're full of water, or solid glass; that's what will be fixed by proper refraction/air polygons.

Lottmedia
09-23-2006, 09:00 AM
Anyone got any tips or a setup for incident angle reflection? I've got a outdoor building scene and I can't get the reflection right on the windows but I'm slightly clueless about IA. :)


Casey :cat:
(now, if I press this...)

borkus
09-23-2006, 10:19 AM
neverko, really cool website you posted. very cool find

nthused
09-23-2006, 01:01 PM
Anyone got any tips or a setup for incident angle reflection? I've got a outdoor building scene and I can't get the reflection right on the windows but I'm slightly clueless about IA. :)


Casey :cat:
(now, if I press this...)

Try 15 to 20 percent at the 90 degree (directly facing you - perpendicular) and 98 percent at the 0 degree mark. Set it opposite for the transparency - 98 percent at 90 degrees and zero to 10 percent at 0 degrees. This is where FPrime has REALLY helped me - takes the pain from testing the surface settings.

Have fun.

Exception
09-23-2006, 01:05 PM
csoars:
Blurred reflection is killing you too... perhaps your quality level is set a bit high.

Warwind
09-23-2006, 01:21 PM
Your refractions could need some work, if you want realistic glass. Take a look at the refraction tutorial here: http://www.the-worms-of-art.com/Tutorials/ It will explain the use of air polygons for correct refraction.
Thanks so much for posting the link to this tutorial--I could not figure out why I couldn't get a glass to look right, and now it's solved. Much appreciated! :thumbsup:

toby
09-23-2006, 01:27 PM
Anyone got any tips or a setup for incident angle reflection? I've got a outdoor building scene and I can't get the reflection right on the windows but I'm slightly clueless about IA. :)


Casey :cat:
(now, if I press this...)
If you're using the gradient, start with 100% at 0, 10% at 90, and at about 20 degrees put the value at about 33%. The value at 0 is the most extreme glancing angle from the camera, where light reflects like a rock skipping over water. 90 is where the surface is perpendicular to the camera, where you get little reflection. And you don't want this gradient to be linear, that's unrealistic, it stays low until it gets close to 0 then shoots up, hence the 33% at 20 degrees.

There's also some shaders that do this for you, Fast Fresnel, Real Fresnel. There's a description of these in the manual with illustrations, and a better description of Fresnel than mine -

For windows it helps a lot to put a tiny amount of bump in the surface, like 1-3%, at a large scale, like 1m or more. This duplicates the slight warp in glass, and keeps them from looking too CG perfect. Just look at a skyscraper photo and you'll see what I mean.

Warwind
09-23-2006, 06:25 PM
I hope this was useful to someone :D
It was to me! Thanks again! :thumbsup:

csoars
09-23-2006, 11:35 PM
Thanks guys - remember this is the very first thing I ever did on lightwave so there was a bit trial etc. Good site thanks nev

coolkew
09-26-2006, 11:40 AM
It normally will happen when rendering using "Ray Recursion Limit" too high. try to play around with this setting.