Render times so different between two machines

[chrisjo]

I'm using Vectorworks 12.5.1 with Renderworks and I'm trying to render a scene which has a file size of just over 4MB. I've seen this same scene render using Custom Radiosity on someone else's machine and it took just over 5 minutes. When I render it on mine, it takes well over an hour and a quarter. I've copied the Custom Radiosity and Renderworks settings exactly, so I really do think the setups are the same.

My machine is a 1.8Ghz Dual Core laptop with 2GB ram on WinXP. System performance in all other applications is excellent, but my render times are so much slower than I would expect.

Any advice would be much appreciated.

Chris

[propstuff]

Much more specific and complete details about the 2 systems would be needed to make a sensible comment about that.

Can you get more info?

[chrisjo]

Thanks for your reply.

The machine I'm using is a Dell Inspiron laptop with Intel Centrino Duo 1.73Ghz processors, 2GB RAM (recently upgraded), ATI Mobility Radeon X1400 graphics card, running Windows XP Media Centre Edition Version 2002. What other info would you need to know?

I appreciate that this is not the last word in PC speed, but it's at least decent, and I just think something is wrong. Last night, I tried to do a Custom Radiosity render of a 10.8MB file with Accuracy set to 80% and Enegy set to 90%. After 7 hours, the enegy had got as far as 16% and it predicted another 84 hours rendering time to go! Can that really be how long it takes to render views?

Like I said, this machine runs really quickly on all other tasks so I'm not suspecting any general system problems.

Thanks for any help.

Chris

[propstuff]

Given the times you mention, and you said that the same scene renders on another computer in 5 minutes, I'd have to guess there is something amiss.

I presume you've optimised the scene for radiosity, but even so; 7 hours to reach 16% is way out of whack

Can you post the file somewhere for others to test render?

[Guest]

What are the specs of the other computer?

What other programs are you running on your computer, including task bar items ?

What about the other computer?

Depending on what type of textures & objects you have, it's hard to say whether or not there's a problem.

[Dave Donley]

Hello chrisjo:

Was the 5 minute render doing the radiosity solution then rendering the solution entirely from scratch, or was the solution already done (in the viewport cache)?

Are you working from a copy of their file? Maybe they set particular objects to override radiosity to not emit and/or not receive? This could affect the solution time a lot.

The number of triangle is almost always the determining factor in how long the radiosity solution will take. The other is how uniform or localized the direct lighting is. When you press Start in the Custom Radiosity Options dialog, how many emitting and receiving triangles are listed? As a guideline, I try to keep the number of receiving triangles below 100K, otherwise things move too slow for my patience level.

[chrisjo]

Thank you all for your advice. I appreciate it.

Was the 5 minute render doing the radiosity solution then rendering the solution entirely from scratch, or was the solution already done (in the viewport cache)?

I don't know whether the 5 minute render was from scratch or not. I think it was, but I don't know for sure.

Are you working from a copy of their file? Maybe they set particular objects to override radiosity to not emit and/or not receive? This could affect the solution time a lot.

Yes, I'm working from an exact copy of their file, so whatever overrides they have, I should have.

The number of triangle is almost always the determining factor in how long the radiosity solution will take... When you press Start in the Custom Radiosity Options dialog, how many emitting and receiving triangles are listed?

It takes so long to even display the number of triangles that I haven't done this test. :-(

To be honest, I've given up on Radiosity, deciding that I will just use Final Quality Renderworks (FQRW) instead and things have been a little better (though I've still had to run the renders overnight). However, my latest file is about 30MB and now even FQRW is taking far too long to be usable. Last night I set it to do a FQRW render and after 6 hours it had only done 9%. Even Fast Renderworks takes 15-20 minutes which makes it really time consuming to review each change.

Could it be that my files are more complicated than they need to be? I don't have many textures in there though I do have a lot of lights. My scene is mostly extrudes and hardly any NURBS. There are no image props and the textures I'm using are all 40k or less. It's just one room - does a filesize of 30MB indicate a problem? When I see other people's VW files they are rarely above 5MB. Is 30MB unusual for a single room space?

Many thanks again,

Chris

[Jim_Allen]

Chris,

Have you tried the "Purge unused" command? It might help reduce the file size, although I don't think it will help with rendering.

I always try to use the fewest lights possible when lighting a scene. The more you use, the more solutions RAD has to compute. I typically will use 1-2 key lights and 1-2 fill. Even still RAD is a dog rendering time wise, but not a bad as what you are getting.

Dave is right about the triangles. Get that number and you will know better what is going on with RAD. I usually use energy at 60-70% and use "override Rad" and " do not reflect" on everything I can to speed up the rendering.

If fast RenderWorks is taking that long then you have some serious stuff in the scene.

Can you upload the file so some of us can play with it? I always like trying to solve other peoples problems - great way to learn how to fix problems and what not to do :-)

[chrisjo]

I've tried to strip out anything that isn't in each scene and that has barely made any difference. I've also tried the Purge Unused command but, as you suspected, it didn't help with rendering. The only thing that has helped a bit was removing all area lights. They seemed to slow it down a lot. I suspect that there are still too many lights, but I don't have time to start the lighting from scratch.

I was wondering if anyone could advise me on their recommended Custom RenderWorks settings so that I can produce renders faster than Final Quality RenderWorks but higher quality than fast RenderWorks. Settings that give a decent compromise between the two would be ideal.

I'm running out of time with this project, so the sooner someone can advise the better.

Many thanks,

Chris

[Jim_Allen]

I mostly use fast Renderworks. that is thew quickest renderer. for Custom i have just used the default settings. i just did a run of a room with 3 lights. Room had furniture, window door, etc. fast renderworks and final quality RW rendered in about 3-5 sec with about the same quality. when i did it with RAd the time was 35 sec with energy at 60% when I upped it to 80% the time went to 1:10.

Can you enmail me the plot and let me see what i find:

jtallen24@cablespeed.com