Page 1 of 2

direct light vs pathtracing

Posted: Tue Jun 08, 2010 12:40 pm
by andrear
I've rendered the same scene in direct light and pathtracing (following the "radiance procedure" involving double resizing via photoshop).
The time request by the two is quite different (20 min. vs 2h.40 min.) and it doesn't seems to me that it correspond to a visible gain in quality.
It is prob. my foult in not doing the necessary corrections to obtain better results, so I simply ask for any suggestion to exploits the right setup.

thank's,
andrea

Re: direct light vs pathtracing

Posted: Tue Jun 08, 2010 2:50 pm
by slatr
I have to agree that the quality tradeoff for speed may not be worth it. Direct lighting is often quite beautiful and much faster.

It might not be as accurate, but I really like the results.

It will be intereresting to see other comments. I saw in another thread where is was mentioned that direct light was more of a preview mode where pathtracing was for final image creation.

For a "preview", your direct light image sure is pretty.

Slatr

Re: direct light vs pathtracing

Posted: Tue Jun 08, 2010 3:18 pm
by Chris_TC
It appears that the sunlight does not actually enter the room which explains the very dark path traced result. I think sunlight can't pass through glass yet.

Re: direct light vs pathtracing

Posted: Tue Jun 08, 2010 4:13 pm
by andrear
hi,
actually I didn't exported the glasses in the obj file, maybe the pathtracing problems arise by doing it on the laptop which downspeed too much the process, btw I'm pretty happy of the results using directlight.
bravi!

bye

Re: direct light vs pathtracing

Posted: Tue Jun 08, 2010 7:42 pm
by havensole
I think it all goes for what you are looking for. Direct lighting gives a good quality render without all of the refined detail of pathtracing. Pathtracing is more for realistic scenes/renders where you need to mimic the real world. The direct lighting render above looks great, but it doesn't look "real". Granted the pathtracing doesn't fully look "real" but that could be settings. Not sure why the light ins't coming into the room if there is no glass there. Odd.

Re: direct light vs pathtracing

Posted: Tue Jun 08, 2010 9:17 pm
by nuverian
I also believe that pathtracing need much more time than directlighting while the results are not than different sometimes.
Maybe when emitters and RLT are here we could judge better, but until then I go with directlighting for most scenes I test.

Re: direct light vs pathtracing

Posted: Wed Jun 09, 2010 12:54 am
by nickliang
I've been using Directlight commercial work, I admit it faster, I am very happy, but I hope it is able to calculate more accurate, Pathtracing I do not like to use it, too slow for my commercial work is not useful I need more efficiency in the calculation of the value of a business process.

totally not agree: big difference

Posted: Wed Jun 09, 2010 7:01 pm
by studiocampus
in few situations very similar. absolutely different in others
the following two images shows a very fast render with white material (better to evaluate the lighting difference than complex materials. the file and settings are the same except for switching between path tracing and directlighting
(by the way, the buildings are a current work of my studio)
aa.png
aadl.png

Re: direct light vs pathtracing

Posted: Thu Jun 10, 2010 1:44 am
by nickliang
pathtracing looks very good, Hope radiance can do better to directlighting, Quality similar to Vray. this's a commercial job needs. Physical body is not realistic for commercial render work.

:D

Re: direct light vs pathtracing

Posted: Thu Jun 10, 2010 8:46 am
by andrear
I'm agree with you that pathtracing give the best results in terms of quality, the question is if it also give the best 'cost-beneficts' performance.
at the light of my (very little) experience with this software and of my purpose doing renders (of my projects as soon during the project itself as for it's final presentations to the client), the time gap is quite big.
I'm waiting with a lot of curiosity the materials light emitters and the light trasmission to achive a complete judgement which, anyway,at the moment goes from very good to optimum.