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View Full Version : Hypervoxels and Multithreading



kmscottmoore
01-23-2004, 06:32 PM
The only difference between these two images is the number of threads set in the render panel. 2 in the first, 8 in the second. (Setting it to 1 looks the same as 2) Any one know why the difference in image quality?

kmscottmoore
01-23-2004, 06:34 PM
Sorry,

For some reason, I can't post more than one image at a time.
This one is acutually the 2 thread one.

Turner
01-23-2004, 08:31 PM
I don't know the answer, but your results are interesting if you're indeed saying the 2-thread render came out better than the 8-thread render.

On my system (G5 dual 2ghz) I got a speed increase from 1 to 2 threads, but a decrease when selecting more than 2 threads...

Hm...

Simon
01-24-2004, 02:33 AM
Mmm I've never noticed any difference when using different threads. Are you sure you didn't accidentally uncheck any of the raytrace options? It sort of looks to me like the top image doesn't have refraction and/or reflection like the bottom one?

Simon.

DONGLE THIS!
01-24-2004, 08:26 AM
hi.
i see your pretty good at the particals.

I have a question. off another subject
how can i move my particals so they leave a trail behind on the ground
i just cant figure it out
thanks

jamesl
01-25-2004, 02:27 AM
I agree with Simon. It's not a Hypervoxel problem... even the main sphere has more specularity. Could you test again?

j

3dgirl
01-25-2004, 08:48 PM
i thought usiung 2 threads meant using 2 processors? in which case what would be the point of setting it above 2?

jamesl
01-25-2004, 09:25 PM
Theoretically, if you're using WinXP Pro with a single P4, you have Hyperthreading, which will show increased performance with multiple threads. That's a good question, though... is this on a multi-proc system?

j

3dgirl
01-25-2004, 11:00 PM
so is it just windows XP pro you have this with? i am on windows 2000 with a dual processor- any advantage to going above 2 threads?

jamesl
01-25-2004, 11:34 PM
I dunno.... I used to see increases with 4 threads on a dual P3 Win2k system... depends on the scene I guess. I always do a few test renders with different settings to see what I get. Even with a dual 2.8 P4 and XPpro, sometimes a single thread is fastest due to data overhead. Taking 15 minutes to do the test can save hours in the final render.

j

kmscottmoore
01-26-2004, 08:46 AM
I re-rendered again, just to make you guys happy, and the results are the same. As I stated before, the ONLY difference was the selection of the number of threads. I rendered these images back to back, so there is no possible way for any other settings to have been changed. The higher thread options rendered faster, but also introduced errors.

If you look inside the water drops, you can see what I can only describe as "streaks" where there should be smooth shadows. I'm still digging through the documentation to find and answer, but right now, my guess is that Hypervoxels is not completely compatible with Multi-Threading.

The system I'm using is a 3D Boxx, Dual 2.8 Xeons, XP Pro.

Turner
01-26-2004, 09:02 AM
Heck, don't do it just for us - do it for you! You deserve it. ;)


Originally posted by kmscottmoore
I re-rendered again, just to make you guys happy

3dgirl
01-26-2004, 02:25 PM
the manual says there are problems with multithreading and certain plugins (doesn't say which) on the net a few i could see were cellshader, sasquatch and something else i've fogotten- but isn't there somewhere where you can easily see exactly which plugins are compatible??!! instead of having to do a trial and error on all your plugins to see which one is causing the problem?

Turner
01-26-2004, 02:44 PM
Hm.

Guess my G5 2x2 won't help in those cases :(


Originally posted by 3dgirl
the manual says there are problems with multithreading and certain plugins (doesn't say which) on the net a few i could see were cellshader, sasquatch and something else i've fogotten- but isn't there somewhere where you can easily see exactly which plugins are compatible??!! instead of having to do a trial and error on all your plugins to see which one is causing the problem?

kfinla
02-25-2004, 05:47 AM
Ive ready several places HV's arent multithreaded, so I'll be interested to test our Realflow water with 2 threads instead of 8, we also got horizontal lines in parts of our render tests. this may be an artifact with a particular setting ie. sprite/ surface/ volume - which all 2 are being used in the water were making.

But if HV's render faster with 2 thread instead of 8, im there.