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Rendertotexture/Lightbaking with Vray, speed and quality...

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  • Rendertotexture/Lightbaking with Vray, speed and quality...

    For my interactive models I was doing lightbaking since good old Lightscape. Then I moved on to 3ds max with radiosity. Although for stills I always preferred Vray.
    Meanwhile I also use Vray for texture baking, but it is so hard to really get good and quick results. To get really clean lightmaps without any artefacts I have to use brute force. I tired various other combinations with irradiance map/lightcache, and although faster, it is still quite slow and lightleaks or other strange things tend to occur.

    I really need clean lightmaps as many models hardly use any textures at all, they ought to have this special "model-look", i am not after realism, but rather clean and perfect lighting, like in these old examples:

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    Now I had to prepare an interactive interior recently and was already quite short in time, but baking lightmaps with vray really made me struggle this time. I should have retweaked the whole scene for radiosity, exchange all lights, materials etc, and I would have been certainly faster as radiosity with regather gives pretty clean results with short render times. Only problem with radiosity are overlapping objects, which tend to produce very hard black shadows, vray is much better in this regard.

    For this example it took 1 hour alltogether to calculate the radiosity solution and bake one lightmap for the entire scene with 1024x1024 resolution:
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    I tired the same with Vray and different settings, and for this I used standard render settings with brute force subdivision cranked to 100 gave. This gave me about 7 hours render time for the same 1024x1024 lightmap while still being quite noisy:
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    Here i used "universal settings" with DMC noise threshold at 0.001 and while already rather clean, it took 23 hours to render the lightmap, which is unacceptable:
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    Are there other settings I could try that you would suggest. Maybe I would be better off with irradiance map, but so far I have not found any setting that would give me artefact-free results in contrast to brute force.

    Thanks for any input!
    Last edited by oluv; 06-05-2014, 01:33 AM.

  • #2
    What did you use for a secondary GI engine?

    Best regards,
    Vlado
    I only act like I know everything, Rogers.

    Comment


    • #3
      In this case I used lightcache to get enough bounces. I used 2cm sample size and 4000 subdivision.

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      • #4
        Good, then if you like, you could send me a scene to vlado@chaosgroup.com so that I can play with it and see if it can be improved; 7 hours for what scene is way way too much. At the same time, 1024x1024 is way too low for a scene of this complexity.

        In general though, baking to vertex colors (like the radiosity engine does) in that case is more advantageous as it is not tied to UV coordinates and you don't have to worry about unwrapping etc. We do have vertex baking in V-Ray for Maya, but unfortunately not in 3ds Max.

        Best regards,
        Vlado
        I only act like I know everything, Rogers.

        Comment


        • #5
          I'll send you the scene, just let me clean it and prepare it for you.
          I reduced the whole scene to 1024x1024, as 2048x2048 didn't give me that many more details. originally i had it split into 2 lightmaps with 2048x2048, but render times would be much too long then. I already often apply noise reduction on the lightmaps, either with smart blur, or with noiseware or neatimage to improve noisy lightmaps, but this compromises quality quite a bit.

          Baking to vertex colors is interesting, like good old radiosity, although i always rendered the radiosity solution to texture, as it usually gets rid of any meshing-artefacts. 3ds max mesh subdivision is by far not as clean as that from Lightscape, which really did a perfect job for

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          • #6
            any news on the problem? i am really curious to try out better settings for the scene. i meanwhile finished the project, here some screenshots from the interactive model. the whole model is covered by a single 1024x1024 lightmap. only some artefacts remained like the glowing edge marked in the last screenshot. interestingly it doesn't seem to be a problem with the unwrapping, because when baking the scene as ambient occlusion the edge remains clean.

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            • #7
              Thanks for reminding me, got sidetracked into other issues - will get to this as soon as I can.

              Best regards,
              Vlado
              I only act like I know everything, Rogers.

              Comment

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