tag:blogger.com,1999:blog-36992715.post1987276467847188923..comments2024-03-25T11:14:26.579+01:00Comments on zap's mental ray tips: Why does mental ray Render (my background) Black? Undestanding the new Physical Scale settingsMaster Zaphttp://www.blogger.com/profile/08935910250942359436noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-36992715.post-24519586099524193982011-11-09T03:11:16.049+01:002011-11-09T03:11:16.049+01:00This comment has been removed by the author.Lily Hockleyhttps://www.blogger.com/profile/09381114732567509770noreply@blogger.comtag:blogger.com,1999:blog-36992715.post-42910170238565725532011-11-09T03:10:53.184+01:002011-11-09T03:10:53.184+01:00Hi Zap,
Great post, however I do have a problem. ...Hi Zap, <br />Great post, however I do have a problem. <br />I have my exposure on mr photographic exposure at about 7. My scene has a background bitmap image with an object sitting on a plane with the matte/shadow/reflection shader applied. My background image is almost completely black, like you said, when I have exposure set to 'physical scale'. I then turn it to 'unitless' which makes my background image right, however any bitmaps I've used on my object i.e. a poster, becomes very washed out with no contrast. The rest is fine, it's just the bitmap images used in the actual model. How can I fix this? <br />ThanksLily Hockleyhttps://www.blogger.com/profile/09381114732567509770noreply@blogger.comtag:blogger.com,1999:blog-36992715.post-73932424136795320922009-01-19T11:22:00.000+01:002009-01-19T11:22:00.000+01:00Lisandro, the inverse for 2.2 is 0.454545... So th...Lisandro, the inverse for 2.2 is 0.454545... So the correct value for midtones would be 0.455Thykkahttps://www.blogger.com/profile/17621017969993377352noreply@blogger.comtag:blogger.com,1999:blog-36992715.post-8277540733670356312008-06-04T23:35:00.000+02:002008-06-04T23:35:00.000+02:00Sorry! Wrong midtones value for gamma...If midtone...Sorry! Wrong midtones value for gamma...<BR/>If midtones on the non-gamma where .43, and you want to use a gamma of 2.2, multiply both, and the resulting value will be:<BR/>midtones = 0.43 * 2.2 = 0.946Lisandrohttps://www.blogger.com/profile/11940123781012537071noreply@blogger.comtag:blogger.com,1999:blog-36992715.post-83156217815090972972008-06-04T23:21:00.000+02:002008-06-04T23:21:00.000+02:00Hi Zap!I post this on CGTalk, but I think this can...Hi Zap!<BR/>I post this on CGTalk, but I think this can be usefull for the readers:<BR/><BR/>playing around with the mr photographic exposure control in 3ds Max, I found a way to get the backgrounds almost "untouched".<BR/><BR/>Select the mr Phographic Exposure Control, and ajust the Exposure Value (EV) or Photographic Exposure to get your image correctly lighted.<BR/><BR/>Set the physical scale to "UNITLESS". The value here, will be the result from the next formulae:<BR/>(note: EV is the value you get from the Exposure Value (EV), even if you used Phothographic Exposure, and the Exposure Value (EV) gets greyed out..)<BR/>Unitless value = PI*(2^EV)<BR/>Examples<BR/>EV = 0<BR/>Unitless value = 3.14 * (2^0) = 3.14 * 1 = 3.14<BR/><BR/>EV = 1<BR/>Unitless value = 3.14 * (2^1) = 3.14 * 2 = 6.28<BR/><BR/>EV = 10<BR/>Unitless value = 3.14 * (2^10) = 3.14 * 1024 = 3215<BR/><BR/>What will mess up a little bit your picture, will be the Image Control...<BR/>But I found some values, that works when you have gamma off.<BR/>Highlights: 0.83<BR/>Midtones: .43<BR/>Shadows: 0<BR/>Color saturation: 1<BR/>Whitepoint: 100 (YES!, 100!!)<BR/>Vigneting: 0<BR/><BR/><BR/>And for gamma 2.2:<BR/>Highlights: 0.83<BR/>Midtones: 2.12<BR/>Shadows: 0.0<BR/>Color saturation: 1.0<BR/>Whitepoint: 100.0<BR/>Vignetting: 0.0<BR/><BR/>Hope this helps someone!Lisandrohttps://www.blogger.com/profile/11940123781012537071noreply@blogger.comtag:blogger.com,1999:blog-36992715.post-68633311605566482752008-03-03T12:03:00.000+01:002008-03-03T12:03:00.000+01:00Hy Zap,thanx for your explanation of the physical ...Hy Zap,<BR/><BR/>thanx for your explanation of the physical scale.<BR/><BR/>As I'm a Maya user: When I set the cm 2 factor in maya to one this would conform to the max setting "physical units" and when I raise the cm 2 factor to anything above 1 this would conform the max setting "unitless".<BR/>Is this correct?<BR/><BR/>In Maya the only really reasonable use of the mia exposure photographic is when I use the physical sky, because this way we use the physical interpretation, or?<BR/><BR/>So in short to work like a photographer and so in a physical correct way is still nearly impossible (at least in maya2008) when we don't use the physical sky. We still have to go the oldschool way and tweak the light intensity till the image looks good.<BR/><BR/>Sorry for this long comment. And thanks for incredible input and help.<BR/><BR/>ciao,<BR/>Larsseqhttps://www.blogger.com/profile/15967044781654534131noreply@blogger.comtag:blogger.com,1999:blog-36992715.post-43623372993973438002008-02-23T03:04:00.000+01:002008-02-23T03:04:00.000+01:00Thank the heavens, you're back. Was worried. Aft...Thank the heavens, you're back. Was worried. After the Gamma deliciousness can I get some framebuffer love? Tips/tricks with mia_x and other shaders for a composite friendly pipeline? (I thought I'd thank you for coming back before making a demand, I'm cool like that.) ;-) As always, thanks for the blog!Davidhttps://www.blogger.com/profile/10598126315294522260noreply@blogger.com