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Author Topic: PovRay rendering time...  (Read 8449 times)

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Sally (MG)

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PovRay rendering time...
« on: December 06, 2007, 12:46:26 AM »

Does anyone else use povRay? I'm trying to find the optimal rendering time vs quality on my system, and with a relatively simple scene it takes forever. (2 HOURS plus)

This one took just over 1 hour, at 800 x 600 with low quality radiosity


This one took almost 3 hours, and it's on medium quality for both. I'm not sure if I can live with the jagged edges and the grainy floor.



The question is...is this supposed to take this long? I've been away from the 3d scene for years, and I thought things have sped up since then. (and if it has, and it's just hardware - onboard ATI Radeon X1250 - could someone point me to a reasonably priced graphics card?)
« Last Edit: December 06, 2007, 02:43:38 AM by Sally (MG) »
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odnorf

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Re: PovRay rendering time...
« Reply #1 on: December 06, 2007, 08:52:19 AM »

Welcome Sally.

The rendering is done by the cpu and not the gpu. The later only does the real-time 3D rendering in 3D games/apps. Your rendering times will improve with faster cpu and more & faster ram. What are your computer specs now?
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Sally (MG)

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Re: PovRay rendering time...
« Reply #2 on: December 06, 2007, 07:10:23 PM »

It's an Athlon 64 x2 dual core 4600+ with 1 gig DDR ram.

I'm running a 32 bit version of windows though (I got a new computer but I used the same old disc of xp pro) ...would that make a difference?
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Nihil

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Re: PovRay rendering time...
« Reply #3 on: December 06, 2007, 07:56:09 PM »

What software do you use for modelling?
What really speeds up rendering is - if the software supports it - more cores, so a quad-core cpu really rocks.

And maybe another renderer? I haven't used PovRay for at least 10 years, so I can't tell anything about it's performance, but maybe another renderer could do the job faster? That's just a guess though.

Tol

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Re: PovRay rendering time...
« Reply #4 on: December 06, 2007, 10:04:37 PM »

It's an Athlon 64 x2 dual core 4600+ with 1 gig DDR ram.

I'm running a 32 bit version of windows though (I got a new computer but I used the same old disc of xp pro) ...would that make a difference?

That configuration should be more than enough for relatively quick renderings of scenes like you showed earlier. I do not use Povray therefore I can´t be specific here, but most of these renderers work in similar ways and it is mainly about optimization both of geometry and lighting setup. Try to study more about Povray´s rendering methods to choose ones that fit most for particular scene.

It seems like you use too much lights with shadows turned on- it not only looks confusing in scene, but they take a lot of rendertime (especially raytraced ones).  Isn´t there by any chance radiosity or other method of GI turned on? Doesn´t look like that (except for that grain), but if it is , it´s another hungry time consumer when it is not set correctly (optimal).

In short- scenes like these should be rendered in few minutes (or ten of minutes at most) on computer you mentioned. It´s not in your computer, it´s in your scene and render setup and easily fixable then :) Try to search any Povray forum for specific tips on how to optimize rendertime.
« Last Edit: December 06, 2007, 10:10:17 PM by Tol »
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Sally (MG)

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Re: PovRay rendering time...
« Reply #5 on: December 07, 2007, 02:05:52 AM »

I was going for low poly count with detailed textures, so it should be faster than it is. But to Tol's suggestion with the number of lights, I believe I've figured out what it is.

POVRay will take into account EVERY light that in the scene, not just what's in front of the camera. Since my entire HOUSE is inside one file, and therefore counted as one scene (and probably doesn't help that the entire first floor is open concept) it counts the track light in the kitchen, the two lamps the in dining room, the light in the living room, and the chandelier in the entry ... every time. (DUH on my part.) I also had every light with shadow, radiosity turned on, as well as sunlight.

I believe I'll be putting up some boundaries...

Thanks guys! At least I won't have to buy any new hardware. ;)
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Tol

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Re: PovRay rendering time...
« Reply #6 on: December 07, 2007, 02:39:15 AM »

Sally: if you have radiosity turned on, then there you go- it is pretty expensive method when it comes to rendertime. Fortunately there are ways how to reduce it.

This article helped me a lot time ago when I learnt about GI lighting.  It´s for Yafray, but main principles should be usable in Povray too, read about Cache method (i think that in most packages it is called irradiance map) which optimizes pathtracing render a lot and makes nice shadow areas in the corners :)
http://wiki.yafray.org/bin/view.pl/UserDoc/CekuhnenTutorial
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Sally (MG)

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Re: PovRay rendering time...
« Reply #7 on: December 07, 2007, 02:48:14 AM »

Tol, thanks for the tip, I'll read it, but I'm just doing a test render now by isolating a room, killing all the windows, and dropping it in a new file. With one light, radiosity at low quality, (and I threw in a couple of mirrors just to trip it up) 3 passes came to 8 minutes.

It was totally trying to compute ALL the lights on the floor, and all of the windows in the entire house. :| I guess turning off the lights in the other rooms and rendering only "night" indoors will help too, but I'm not sure yet.
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Re: PovRay rendering time...
« Reply #8 on: December 07, 2007, 05:18:26 AM »

i do not use povray but you need to figure out what kind of rendering system it uses. Radiocity, Raytracing, GI, QUASI, Lightmap, etc etc etc. Each one affect rendering time. But yes rendering takes a long time... not much you can do.. most raytracers have loads of setting.. so playing with them helps a lot.

To effectively manage rendertime you need a understanding of exactly what is happening and how the rednering is working... as trail and error can tale a while.... but there are bazzillions of 3d Render theroy books and webpages about to teach you that stuff... Like tol said the theroy should transfer to all rendering.


There is an excellent downloadable tutorial at Gnomology about dropping rendertimes in vray... that i recommend.. even if not using vray... in the tut he drops a 40min render time to 15seconds with no real drop in quality.... very interesting stuff.

SPEED VS QUALITY IN VRAY
http://gnomonology.com/tutorial/62
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