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  1. #1

    Maya Mental Ray Render Question

    Hi,
    Mental Ray is crashing when rendering the final Mechs assignment in the Maya Fundamentals course and I'm assuming its because of an overtaxed system and/or not enough RAM. (I'm using a quad core with 8 gigs RAM and Windows 7, 64-bit OS, with Nvidia 560 TI graphics)--and am rendering the assignment in HD format. It renders fine using the Maya Software, so the problem seems specific to Mental Ray. The Nvidia drivers are currently updated, as well as the OS.

    Is it reasonable to assume its crashing because of RAM? I'm a complete noob trying to get a sense of what my hardware can and cannot do--and how to analyze rendering issues. Other than the HD resolution, the settings are those suggested by the course. Is it unusual for Mental Ray to crash or is this something you just work around? IPR crashes all the time, as well--so much I don't even like using it.

    I sure appreciate any tips or advice anyone might have--the MF course has been wonderfully fun--and am curious how to deal with rendering in the future.
    Last edited by rwilliams23; 04-13-2012 at 12:21 AM. Reason: Corrected amount of available RAM

  2. #2
    Boy you’re making real good time ripping through the tutorials.

    First assuming that you are following the tutorial and not adding any extra bling bling then your hardware is more than adequate considering the much lower hardware specifications that came out at the time Maya Fundamentals was released.

    Crashes in general are rather difficult to solve and can usually be tracked down using divided and conquer techniques and in context your problem could be in either exceeding the limitations of the video card or your scene has a corrupted element with a value that causes the rendering engine to crash.

    Assuming that you have a stable install of Maya I can usually solve my own crashes by examination of the scene assets and compare them to the limitations as to requirements.

    Driver wise I know the limitations of the DX driver (which I also assume Maya uses for fast draw) where if texture resolution limits are exceeded this will cause a crash so that would be a good place to look first by comparing the overall sizes of you textures to see that they don’t exceed the limits of DX and the max resolution of the video card.

    It’s also a good idea in general to not use textures resolutions that do not conform to the power of 2 rules when using the DX driver.

    You could also switch to OpenGL for rendering at the cost of edit speed, as it’s a lot more render friendly.

    Another general problem that can cause rendering crashes is a corrupted scene element. As an example you could get carried away detaching surfaces of an object to the point of detaching the last few faces and left with a nul object that contains no values.

    You can find this by hiding each of the scene elements one at a time and once the entire scene is cleared out if you still have an object in the scene than that’s a nul. Delete it and there is a good chance you solved your rendering problem.

    Another thing you can try is to save your scene, do a reset, and merge the project into a clean environment.

    Something to try and a bit harder to find is a corrupted object. You will need to bring each element into the scene and render them out one at a time and keep adding elements until you get a crash. You can the try fixing that element and repeat the process until all elements have been gone over.

    Based on my experience the problem is usually fixed with in this area.

    As a last note be sure to validate the scale of your scene as it relates to relative scale. When messing around with systems that requires real world values strange things can happen if the local scale of an object is off but usually does not result in a crash.

  3. #3
    Frankie, thanks! This is just what I need to start thinking about the problem beyond just staring at the screen. ;-)

    a good place to look first by comparing the overall sizes of you textures to see that they don’t exceed the limits of DX and the max resolution of the video card.

    How do you go about calculating the sizes of textures in a scene?

    It’s also a good idea in general to not use textures resolutions that do not conform to the power of 2 rules when using the DX driver.

    Power of 2 rules? I googled around to see how this worked, but didn't find anything that directly related. Do you know a good reference that could get me up to speed? I'm not asking you to go into detail on all this--I think at this stage I'm looking for good references where I can slowly absorb things.

    As a last note be sure to validate the scale of your scene as it relates to relative scale.

    As in freezing transformations?

    It makes sense its probably a problem in the scene itself. Next time I'll render more often as I go to help pinpoint problems.

    I'm bookmarking your post to help in the future. Thanks again!
    Ric

  4. #4
    For texture management I use Thumbs + as it reads almost every file format out there. If you made the textures your self then you should know your resolutions already but there are some sources there that supplies huge textures that DX cannot swallow.

    The power of 2 rules is a game developers thing.

    1024 X 1024
    512 X 1024
    2048 X 2048

    That kind of stuff as most game engines will resize the image down to the next lowest power of 2 anyways. Though I would mentioned it as I’ve had problems in the past with textures like 4000X4000 crashing things.

    I did a blog thing as to scale but blogs are no longer around but did find a new home.

    http://www.custommapmakers.org/viewtopic.php?f=16&t=361


    One thing I forgot to mention is you should also do a test render on a scene you know should be healthy. An example file that comes with Maya should do the job just to make sure that there is not a general problem with the install.

  5. #5
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    In Maya there is no switching between openGL and DX, as its cross platform openGL is the only option (a d3d.dll is required at install for HLSL support and you can write your own DX viewport, but lets assume things are vanilla).

    MentalRay uses RAM a bit different from the software renderer IIRC, how far into the render do you get before the crash?
    Might be worth having Task Manager open when you start the render and see what memory usage is occurring.

    There are a lot of particles in the scene, are these all cached out before you start rendering.

    Also mentalRay will open a commandPort when it starts, some firewall applications have an issue with this. Could cause things to trip up, a long shot but hey hoo.

    Hope you get it figured out see we can see the result
    There is an exception to every rule, apart from this one.

    Current giveaway: Freelance Quixel suite (...working on details)

  6. #6
    how far into the render do you get before the crash?

    It works for a few minutes, then crashes.

    It started crashing when I increased the tesselation in the last video. When I returned to an earlier save before increasing the tesselation, Mental Ray completed, but created a black screen. I hadn't rendered using Mental Ray before until this point in the exercise.

    are these all cached out before you start rendering?

    Yes.

    some firewall applications have an issue with this
    Interesting--but it's worked in the past so that's not it in this case.

    Hope you get it figured out see we can see the result.

    This is kind, but gives me pause. It "works" now only because I rendered the earlier scene version using Maya software--but the rendered video is something only a mother could love and I can't imagine anyone wanting to see it. I made mistakes along the way that I didn't discover until much further along; such as not having the Mech face along an axis. So I animated two Mechs--one walking along the axis so I could follow Zak's instructions--the other walking like a prowling cat. :-) The terrain though is broken because when separating pieces for the footsteps, I had to cut multiple times.

    I've been biting at the bit to create my own video--starting ADP--so rather than polishing the Mech exercise, I've let it sit. I'm just eager to do my own designs and exercises.

    Part of what Fundamentals shows me is how BIG these projects are--huge amounts of technical and artistic detail that have to be considered. It's easy to lose the "focused spark" in the midst of technical considerations and the shere volume of unknowns. For instance, I'm terrible at animation--it doesn't come easy at all--but when I first animated the Mech and showed it to my wife, she laughed and laughed--it had character, done with a beginner's childish glee. When I tried to "fix" things, it lost it's character and walked like a badly wounded cripple ;-) I've got a lot to learn.

    How does one learn all these things? Patience, thoroughness, practice, passion, and humor. Should I keep working on the Mech? My attention has moved to ADP, but your comment makes me wonder. Why would anyone other than my wife want to see the Mech video? All it shows is how much I've got to learn! ;-) I think what might be pushing me away from it at this stage is it's not MINE--it's an exercise--and now I want to see what I can do given the biggest box of toys in the world.

    Long answer--but was surprised to hear you might want to see the darn thing.

    Thanks, guys--3DBuzz is the best!
    Last edited by rwilliams23; 04-18-2012 at 07:49 AM.

  7. #7
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    Part of what Fundamentals shows me is how BIG these projects are--huge amounts of technical and artistic detail that have to be considered.
    This is why things like a good pipeline and solid workflow are important. If you feel you are fighting the technical aspects its easy to lose your "focused spark".

    Sounds like it would be a good idea to take what you have gained from the fundamentals course and either, make a new scene of your own design, or re-work something in the Mech scene to put your own 'stamp' on it.

    That's one of the reasons I like seeing other people fundamentals renders, lots of scope to put a different spin on things.

    This doesn't help much with the crashing render however:
    Any chance of seeing a single frame mentalRay render, assuming it completes, saved out from the render view?
    Also, if you feel comfortable doing so, you can always email the project (minus rendered images and PDC files!) and I'd be happy to test it here
    There is an exception to every rule, apart from this one.

    Current giveaway: Freelance Quixel suite (...working on details)

  8. #8
    It's a pleasure to show a frame ;-)

    Maya crashes on the "Tesselized" version and only render's a black frame on the "Pre-tessalized" version. The script editor gives these two errors on the "Pretessalized" version:
    // Error: (Mayatomr.Geometry) : detachedSurfaceShape10: object is not a nurbs surface, ignored //
    // Error: (Mayatomr.Geometry) : detachedSurface8detachedSurfaceShape2: object is not a nurbs surface, ignored //

    Here's what I get when rendered with Maya software:

    Click image for larger version. 

Name:	MechAttackShot2Frame355.jpg 
Views:	71 
Size:	58.0 KB 
ID:	72671

    My style tends toward lower, tighter camera angles w/ wider lenses--and a much moodier atmosphere and lighting. As far as I know, there's no real reason here to use MentalRay--I was just fooling around trying to get a sense of the tools. You're right--I need to be confident with the pipeline/workflow--and should take the time to debug the MentalRay problem. In the "Pretesalized" version--could a black screen be as simple as a Light Linking problem?

    If I send you the project, what files/folders specifically would you need?
    Last edited by rwilliams23; 04-18-2012 at 01:27 PM.

  9. #9
    Have to run to work, but one more thought. The black MentalRay render is specific to certain cameras. I've 6 cameras--it works on some and not others. Is there a camera specific setting that would affect MentalRay this way? Really appreciate the help. :-)
    Ric

  10. #10
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    If I send you the project, what files/folders specifically would you need?
    Just the "Tesselized" and "Pre-tessalized" maya files should be fine.
    I still have the textures used in the project (unless you did something 'custom' with yours like Frankie suggested?)

    Can test it on a few different machines here, which release of Maya are you using there?

    There is an exception to every rule, apart from this one.

    Current giveaway: Freelance Quixel suite (...working on details)

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