dayvbrown Posted November 25, 2008 Share Posted November 25, 2008 Hi all, Am rendering a fog pass (first time i've had to do it since switching over to houdini) and am having some serious banding issues. I'm using the supplied vex_litfog shader with a spot light and (with the exception of the banding of course) getting exactly the results i want. So.... whilst i've been trying and failing to get it working for the better part of the afternoon assume that i've tried nothing and bring on any thoughts\suggestions, no matter how basic! Much appreciated, Dave. Quote Link to comment Share on other sites More sharing options...
dayvbrown Posted November 25, 2008 Author Share Posted November 25, 2008 Hi all,Am rendering a fog pass (first time i've had to do it since switching over to houdini) and am having some serious banding issues. I'm using the supplied vex_litfog shader with a spot light and (with the exception of the banding of course) getting exactly the results i want. So.... whilst i've been trying and failing to get it working for the better part of the afternoon assume that i've tried nothing and bring on any thoughts\suggestions, no matter how basic! Much appreciated, Dave. PS - rendering to .tif files the attached jpg is just for example purposes! Quote Link to comment Share on other sites More sharing options...
geneome Posted November 26, 2008 Share Posted November 26, 2008 You might try adding dithering control to the mantra node (and upping the dithering) through editing the render parameters and add dither under the mantra 9.5>Output folder. Also, if your rendering out tiff, I gather it's 16 bit? You might want to see what 32 bit does to the banding. Quote Link to comment Share on other sites More sharing options...
old school Posted November 26, 2008 Share Posted November 26, 2008 Could be the display. Usually 16bit is enough to get smooth gradations. The .jpg you attached crushes 99% of the information in the image down to 8bit/channel... To see if indeed there is banding first make sure that mplay does not have the option to load images as 8bit (default is off so if you didn't touch anything you are ok). Then loading in the full 16 bit tiff image press the "Adapt to Full Range" button in mplay to see the fog expanded to 0-1 to see if indeed you have banding. If your ultimate target is film or a medium that can handle 16bit (or 12bit) then no issues. If your ultimate target is broadcast tv then you will have issues. See geneome's answer and add some dithering to the Mantra ROP. This is an age old problem in broadcast tv. Quote Link to comment Share on other sites More sharing options...
dayvbrown Posted November 27, 2008 Author Share Posted November 27, 2008 Could be the display. Usually 16bit is enough to get smooth gradations. The .jpg you attached crushes 99% of the information in the image down to 8bit/channel...To see if indeed there is banding first make sure that mplay does not have the option to load images as 8bit (default is off so if you didn't touch anything you are ok). Then loading in the full 16 bit tiff image press the "Adapt to Full Range" button in mplay to see the fog expanded to 0-1 to see if indeed you have banding. If your ultimate target is film or a medium that can handle 16bit (or 12bit) then no issues. If your ultimate target is broadcast tv then you will have issues. See geneome's answer and add some dithering to the Mantra ROP. This is an age old problem in broadcast tv. Hi guys, thanks for your suggestions, i've gone through and added some dithering and upped the tifs from 16 to 32-bit and it seems to be keeping the compers happy so that is always good (if slightly disconcerting). It was still reasonably prominent on my display even with the adapt to full range but they seem to be able to work it. Thanks again, Dave. Quote Link to comment Share on other sites More sharing options...
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