sibarrick Posted October 30, 2004 Share Posted October 30, 2004 A question for anyone who's been testing out these SSS ops...It occurs to me that this whole business with the automatic determination of the pointcloud density (in the SOP HDA), while a nice idea in theory, seems to be turning out to be not so useful in practice. Is anyone using it, or does everyone go "manual" with it? 14567[/snapback] I've only used manual so far, just cos on the models I've worked with I just end up with too many points in my clouds and the whole thing chokes. Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted November 1, 2004 Author Share Posted November 1, 2004 Hi Simon, Any chance of a hint about where to find this stuff? Is it mentioned in the paper? 14615[/snapback] The paper includes a few materials, and the actual measurements for these can be found here. And then there are a few independent efforts to publish BRDF measurements from different institutions. The main one is the CUReT database. There are others that use their own protocol for the measurements, like the one that NIST puts out, or the one by MIT. And there are other sources of BRDFs for large ecosystems, like the one here. However; these are raw measurements that you'd need to convert to the homomorphic format first; if that's the representation you choose to go with (but as you can see, there are alternative representations out there ). I've only used manual so far, just cos on the models I've worked with I just end up with too many points in my clouds and the whole thing chokes. 14630[/snapback] Yup; I'm finding the same thing. It was a nice idea, but... oh well.. I think I've made up my mind to remove the automatic thing now. Thanks Simon! Quote Link to comment Share on other sites More sharing options...
Jason Posted November 1, 2004 Share Posted November 1, 2004 I must say that I've never set it to Manual. What I do is set the Samples per Disk to something low, like 3, and then increase that until I get the density I like. It makes more sense in my head to think of Samples Per Disk than total samples. Maybe the SOP needs a "AutoCook" toggle that could make the generation of the points optonally happen at a button-stroke instead? This way you could give some feedback to the user about how many points are going to be scattered before you actually incur that cost? Does anyone know where it slows down the most? Is it large areas, or large numbers of polys or large numbers of points that slows it down the most? Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted November 1, 2004 Author Share Posted November 1, 2004 I must say that I've never set it to Manual. What I do is set the Samples per Disk to something low, like 3, and then increase that until I get the density I like. It makes more sense in my head to think of Samples Per Disk than total samples.Maybe the SOP needs a "AutoCook" toggle that could make the generation of the points optonally happen at a button-stroke instead? This way you could give some feedback to the user about how many points are going to be scattered before you actually incur that cost? 14668[/snapback] Huh... OK. Maybe an "estimate" tab then -- shows you what the estimated density would be for the given scattering distance, but doesn't actually create the points.... Alright. I'll try that. Thanks! Does anyone know where it slows down the most? Is it large areas, or large numbers of polys or large numbers of points that slows it down the most? 14668[/snapback] I'd say large number of points, but perhaps more importantly, large number of Points to Filter more than anything else.... Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted November 2, 2004 Author Share Posted November 2, 2004 Hi all, Another update. Wooohooo! Things that have changed: *) The single vop is now split into two separate vops -- one for multiple scattering, and another for single scattering. *) Reworked the auto-generate portion of the SOP HDA, so that now the estimate is given as just that: an estimate. It is then up to you to use it or not by toggling the wonderfully-named "Use Density Estimate" toggle. *) Added help cards for all the OPs. *) Changed the style sheet in the packager so that it matches the orange look of the new help cards in v7.... very important, that! *) Fixed a small bug in the single scattering code where the samples counter for the chromatic loop was being updated in the wrong place. *) Initial commit to Subversion (migrating from good'ol CVS.... very scary :cry2:) Uhmmmm...... I think that's it... Take it for a spin, and let me know what you think. Thanks! SSSfull4.zip Cheers! Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted November 11, 2004 Author Share Posted November 11, 2004 OK; I cleaned up a couple of small things, and uploaded it to the Exchange. Cheers! Quote Link to comment Share on other sites More sharing options...
TheUsualAlex Posted November 12, 2004 Share Posted November 12, 2004 Many thanks to you, Mario! Quote Link to comment Share on other sites More sharing options...
Jason Posted November 12, 2004 Share Posted November 12, 2004 OK; I cleaned up a couple of small things, and uploaded it to the Exchange.Cheers! 14873[/snapback] Hey Mario, This is great of course! It seems this thread lends itself to a great OdWiki discourse too. It'd save us pinning the topic forever (which is just what I'm going to do right now, lest it ever drop off to Page 2 of this forum;)) Quote Link to comment Share on other sites More sharing options...
edward Posted November 12, 2004 Share Posted November 12, 2004 Much thanks from me too! Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted November 12, 2004 Author Share Posted November 12, 2004 Arrrrgh.... how typical! I was trying out some ray-jittering code for single scattering, and I accidentally uploaded that version to Exchange. Needless to say, that version was buggy. I've now updated it with the correct one. Sorry everyone! I always screw up these postings...<sigh> Quote Link to comment Share on other sites More sharing options...
Jason Posted November 12, 2004 Share Posted November 12, 2004 Arrrrgh.... how typical!I was trying out some ray-jittering code for single scattering, and I accidentally uploaded that version to Exchange. Needless to say, that version was buggy. I've now updated it with the correct one. Sorry everyone! I always screw up these postings...<sigh> 14882[/snapback] What a cheap trick to push your Number Of Downloads! Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted November 12, 2004 Author Share Posted November 12, 2004 What a cheap trick to push your Number Of Downloads! 14886[/snapback] Actually; I noticed that the number of downloads (and the nice rating ) disappeared when I uploaded the new version... so much for my evil ploy Quote Link to comment Share on other sites More sharing options...
sibarrick Posted November 16, 2004 Share Posted November 16, 2004 Hi Simon,The paper includes a few materials, and the actual measurements for these can be found here. And then there are a few independent efforts to publish BRDF measurements from different institutions. The main one is the CUReT database. There are others that use their own protocol for the measurements, like the one that NIST puts out, or the one by MIT. And there are other sources of BRDFs for large ecosystems, like the one here. However; these are raw measurements that you'd need to convert to the homomorphic format first; if that's the representation you choose to go with (but as you can see, there are alternative representations out there ). 14667[/snapback] Thanks Mario, I only just found this reply. Good stuff Quote Link to comment Share on other sites More sharing options...
zoki Posted December 27, 2004 Share Posted December 27, 2004 my try with sss and mantra, model done by me in maya Quote Link to comment Share on other sites More sharing options...
djpeanut Posted April 5, 2005 Share Posted April 5, 2005 For some reason the VOPs for the SSS on the exchange won't show up. I've installed both OTLs over and over again, the SOP HDA is fine but I can't find the VOPs anywhere... [EDIT] Ignore me.... Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted May 13, 2005 Author Share Posted May 13, 2005 Hi all, I've been asked by a couple of people if I could post the slides from a talk I gave on this topic recently ("Toronto Technical Evening"). I'm not sure how useful they are since they are... well... slides... but maybe they help clarify some of the stuff talked about in this thread... plus it's got some more purty diagrams So I'll post them here (as a pdf file) until I have a chance to flesh it out some more and maybe migrate it to the Wiki... SSS4.pdf P.S: It just deals with multiple scattering (none of the single scattering stuff there). Cheers! Quote Link to comment Share on other sites More sharing options...
stevenong Posted May 13, 2005 Share Posted May 13, 2005 Hey Mario, Thank you very much for posting the slides! I understand SSS & the use of point clouds much better now. :notworthy: Cheers! steven Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted May 13, 2005 Author Share Posted May 13, 2005 Thank you very much for posting the slides! You're very welcome, sir... and... I understand SSS & the use of point clouds much better now. :notworthy: Woooohoooooo!!! See... it's not that tricky after all! Cheers! Quote Link to comment Share on other sites More sharing options...
Jason Posted May 16, 2005 Share Posted May 16, 2005 Hey Mario, I was knocking about Wikipedia and came across these links: Wikipedia: Scattering -and an interesting link from within: Complex Photonics Fun read:) Quote Link to comment Share on other sites More sharing options...
Mario Marengo Posted May 16, 2005 Author Share Posted May 16, 2005 I was knocking about Wikipedia and came across these links: 18252[/snapback] Thanks for the references Jason. Very interesting stuff. I was familiar with Rayleigh and Mie scattering from using them in atmosphere/volume shaders, but the coherent-light (laser) effects are pretty mind-boggling (not that I can follow all the dense math in there, just the main descriptions). As you say... "fun read", thanks Cheers! Quote Link to comment Share on other sites More sharing options...
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