You can try putting a dome around your scene to "trap the photons from bouncing “forever”.
Regards,
Mike
Edit…
but there
are MR features in 2009 that are not to be lived without. :drool:Regards
Bri
100 % in agreement with Brian. 2008/2009 have been well worth our subscription. Especially 2009.
I am getting some shadow artefact problems with the daylight system. Please see attached image. In the old days I’d up the shadow bias, but what would I do with Mental Ray’s daylight system to overcome these little black lines (and highlights in shadow areas as well).
Thanks!
PS. In case you wonder what you’re looking at, it’s a side view of the back of a wing fillet, butting against the fuselage of an aircraft! 
Hi,
I’m not a guru on it but there may be a problem with your modelling, I mean problems with polygons…
If you can attach of a wireframe looking, it may be more obvious to see what problem is !
But trying to use more polygons (maybe a meshsmooth) can be your solution…
It’s not the quantity of poygons for sure (triple subdivided), but perhaps the shape (long/thin and slanted). See attached wireframe.
I’ve seen similar artefacts on geospheres as well, though. So what I’d really need is something alike the old time shadow bias setting to tweak the threshold for shadow casting a little. Does such a thing exist for mrSun or can it be tweaked in the render settings somehow?
Hey,
Recently I started to learn mentalray … really it is amazing engine for rendering in every thing ( lighting , shading , rendering , rendering time,…)
But this is an incommodity thing … it is the geometry weight and plygons counts … it is affect on rendering memory and make the rendering very slowly in additional to that the mentalray consumes all the memory of the pc and i cant do any thing while the rendering process.
i think this problem existing more in max 2009 and it occures whatever i convert the geometry to proxies
In VRay i can render Millions of polygons and nearly five times of geometry that can mentalray bear with less memory
are there any solutions of this problem ?But this is an incommodity thing … it is the geometry weight and plygons counts … it is affect on rendering memory and make the rendering very slowly in additional to that the mentalray consumes all the memory of the pc and i cant do any thing while the rendering process.
i think this problem existing more in max 2009 and it occures whatever i convert the geometry to proxies
In VRay i can render Millions of polygons and nearly five times of geometry that can mentalray bear with less memory
I think it was discussed earlier topics and their thoughts were similar to your description… It does not happen in max 9 or 2008 versions. They are fairly fast…
I’ve seen similar artefacts on geospheres as well, though. So what I’d really need is something alike the old time shadow bias setting to tweak the threshold for shadow casting a little. Does such a thing exist for mrSun or can it be tweaked in the render settings somehow?
I think your problems is because of mesh order. What I mean in earlier message is that… This triangle mesh looking may possible cause a lighting problem in your scenes, especially when it has the same problem with geosphere…
And I think this is not only your case, but a general problem in MR! Is there anyone who can confirm or experienced this before…
thx alot man for ur fast replay
could u post the link of the topic which the discussion was in it ?
I didn’t read the entire poll -sorry if anyone has talked about this before.
I ve been having the same problem for over years, and I couldn’t get any efficient render with dbr until today. My situation was like this:
Single machine renders the scene in 45 secs while 2 or more machines render it in more than a minute. The apparent reason of the latency is an irrational delay in the finishing of certain buckets. I say irrational because those buckets -which take for instance 30 seconds to finish- are normally rendered by both machines (when each machine renders alone) in less than a second.
More than 90% of my DBR renders were taking more time to render, than a single machine render attempt.
My network was composed of gigabit ethernet cards, which are connected through a 100 mbit router. Today I ve bought a gigabit switch and connected the cards through it. I retried DBR. The results are surprising.
All my DBR attempts decrease the rendering time as it has to be. Addition of extra servers to render speed is directly proportional to the server’s cpu speed. It dramatically increases render speed in both single frame or animation rendering.
Network delays seem to be the reason of this delay in rendering of certain buckets.
DBR gained a meaning right now.
Hey, Skyraider!
I get those artefacts when I render through a User viewport (or Orthographic as they call them nowadays), or a top/front/left-and-so-on. It seems Mental Ray only likes Perspective viewports, and Camera viewports. It isn’t that simple, that you are rendering through a User viewport instead of a Perspective one? It looks like the kind of artefacts you get when you do that…
And as far as I can tell, there isn’t much you can do about the shadows from the mR Sun, they should work just fine, and they usually do. No “Shadow BIAS” slider or anything.
Hope this helps, Wsknin
Hmmm that’s interesting! I am actually rendering through a camera, but one with a very narrow field of view (0.5 degree) to get a near-perfect sideview with decent reflections (since user viewports screw up reflections). It will be interesting to see if these artefacts disappear when I get closer to the subject a little and open up the FOV.
Thanks for your answer in any case!
Wskin, thanks again, you nailed it. At 0.5 degrees I get artefacts, at 5 degrees I don’t. So I’ll just tweak till I get it right THANKS
hi
i m trying to render a plane with opacity map, which renders ok , but i have a huge problem. the ground that is reflective renders the white area of the plane as white without recognizing the opacity map… So at the end i get a transparent plane but a non transparent reflection of it… anyone have an idea!!!
thx
Could you please post a small render image to see whether it’s a setting related problem or a bug?
Do you need transparency? Move your transparency map to the Cutout map slot and see if that fixes it. Keep in mind that transparent objects still refract.
HTH
has anyone else encountered the problem of self illuminated objects, or lights that are “visible in rendering” creating lots of noise on reflective objects?
here are three images to show what illustrate my query.
smoothest
two lights visible
multiple self illuminated objects
any help would be greatly appreciated.
I think that’s an expected result from having very small, very bright light sources. That scenario simply takes far more samples to clear than the two large visible light sources.
thanks jeff. i guess my next test should be if the small light sources were lights isntead of geometry would it be any different result.
so i guess from what your saying any room with can lights just takes longer to render as smooth because they are so bright and so small. anybody found a workaround?
Just an idea… try giving a radial gradient cutout map to the self-illuminated planes, to blur their edges basically. Maybe it will smoothen it out a bit? Maybe not…