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Thread: Radiosity "Blotching"

  1. #1
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    Question Radiosity "Blotching"

    I'm doing an achitectural render and the geomentry looks great, and so does the render on a still frame. But when I render the animation it seems to calculate the radiosity diferently for each frame, resulting in a "blotching" effect. Any Help?
    My radiosity settings:
    Interpolated
    intensity 300%
    RPE - 5 * 15
    Tolerance .232
    Minimum Evaluation 200 mm

    Anti-ailiasing Low
    Motion Blur Normal

  2. #2
    Registered User drclare's Avatar
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    Yeah, i think radiosity does that. I don't have a lot of knowledge about radiosity, but if you turn shading noise reduction on in the global illumination settings, that should help.

  3. #3
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    Don't forget to cache your radiosity solution, that will solve the problem.

  4. #4
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    Thanks, that's what I needed. Plus I accidently posted this same Question in the general help forum. O.K. I'm new here

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    Radiosity for animations can be a tricky task. Mainly because the rendering speed but also for the random calculations that make it all flickering.

    If the light is fixed, then I personally would try to bake the light into a UV map. The advantage of baking is simply that your computer only need to calculate radiosity ones, then you can render your animation quick and also preview it at realtime with opengl. The down side is of course that it takes a lot of time to bake radiosity.
    Last edited by claw; 06-12-2003 at 02:48 PM.

  6. #6
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    also...use full precision blur on your HDR image from the image editor
    will help cut down on the blotches...wont help the flickers tho

  7. #7
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    What settings should I use for Baking,
    Monte Carlo or interpolated
    What Res 512?
    Just illumination or color and diffuse too

  8. #8
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    -What settings should I use for Baking, Monte Carlo or interpolated?

    Montecarlo gives the best result, no doubt. However, interpolated can be tweaked for faster rendering times. Keep in mind that if you're going for interpolated, increase the number of rays! When baking, Lightwave bakes every thing in the scene, not just where the camera is pointing, thats why you need many rays.

    Montecarlo works best if there are lots of light sources in the scene. If not, you need alot of rays to get good quality.

    -What Res 512?

    The resolution of the UV map depends on how detailed your object are. Say you have a big room with large walls, then I would give that room its own UV map and bake it in say 1000 to 2000 pixels. If there are other object in that room, say tables and cheers, give them their own UV maps as well. One good rule is, Bake large areas in high res and small things in low res.

    -Just illumination or color and diffuse too?

    If you want to bake everything, so the bake almost looks exactly like your F9-render, then you should bake color, illumination and diffuse. However, I think its better to only bake the illumination and the diffuse. Its give you more control later, when compositing the layers.

    Normally when the bake is finished you add the baked texture to the luminosity channel and turn the diffuse to 0%. That works pretty well. A more interesting method is to add the bake to the diffuse channel (remember the diffuse controls the amount of light). If you then placing out several pointlights you will see that they light the room up, but only where the diffusechannel says it can. The great thing about this is that bump-maps can be use, and you have more control over the lights intensity, color e.t.c.
    Last edited by claw; 06-12-2003 at 03:26 PM.

  9. #9
    Gold Member Beamtracer's Avatar
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    There are a number of threads in the old Newtek forum concerning radiosity blotching.

    This is one of many:
    http://forums.newtek.com/discus/messages/2/10634.html?
    Moral of the day:
    Worry about your own morals, not someone else's!

  10. #10
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    Thanks claw, thats the info I needed. I also read a few tutorials on baking.

    My computer is freezing now though when I try to bake. I have the plugin on four texture maps, because I have four different UVs. I'm rendering out to pct24 with a resolution of 800 to 1000. Should I increase my seg memory limit.
    I running 7.5 on a G4 Dual 867

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    I don't know if you're running LW under OSX, but if you're running it on OS9, then there could be some bugs that causing it to crash.

    However, Baker is a little funny on mac actually. First of all, the baker interface will appear in the center of the screen. So If you have your render-window there, you will not be able to watch the Baker's progress-bar, and you can't cancel the operation. Its not like that on windows

    So, move away the render window before you try to bake!

    I never have a freeze with baker, actually baker is a bit slow to response. So if you clicked cancel, it may take a while to get it to stop. Start terminal.app and write "top" then you see that LW actually is working.

    Other things that may get you think Baker has crashed LW is that it takes a lot of time to bake radiosity! It can take several hours, depending on the complexity in your scene. A good thing that you can do to get an idea on how long it will take to bake, is to just bake in small ress first, lets say 250*250, then I think you multiply the time with four, every time you double the ress.

    Last thing, I would try to bake to a 24bit TGA or PNG file, I never used pict format in LW, don't know how well it works.

  12. #12
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    THanks man. I'm running under OSX 10.2.5. I'll try a different format than .pct . I let it render overnight and it was still on it's first pass and lightwave wasn't doing anything.
    I'm using interpolated, 6*16
    tolerance 0.1
    100mm Eval
    Something Wrong There?

  13. #13
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    The radiosity setting seems ok to me. How complex is the object you're going to bake?

    Also, you say LW only is on it's first pass the morning after. When you bake, LW is actually baking via the baker shader, its not using LW's rendering engine (not sure, though). So actually, you can't judge how much it baked by looking at which pass it's on. When LW baking, its always on pass1

    Any way, try to bake in low ress first, about 150*150, just to see if it's works.

    Good luck!

  14. #14
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    Thanks, I'm going to rty again tonight. My scene is about 200,000 polygons.

  15. #15
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    Thats quite a large scene you got there!

    It's gonna take a while to bake I think.

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