hatrick Posted January 28, 2009 Share Posted January 28, 2009 hi, i ve some issues with camprojection in houdini... first: alphachannel... i d like to edit my layers for the projection in photoshop... my tifffiles should contain the alpha transperacy but in houdini s compviewer the aplphaarea is displayed white.. so it does projected on my geometry ... i tried a little workaround with a lumykey an a premultnode than converting into a .rat file sadly it doesn`t work either... please help me out HT Quote Link to comment Share on other sites More sharing options...
mrice Posted January 28, 2009 Share Posted January 28, 2009 Lotsa ways to projections, its kind of hard to know whats wrong without seeing a file... Quote Link to comment Share on other sites More sharing options...
hatrick Posted January 28, 2009 Author Share Posted January 28, 2009 here`s a screenshot... the white area shoud be transparent.... may looks a bit weired i m at the beginniing of that scene:) currently it`s a rat file converted from a photoshop - tiff with alpha one further question bout projection... is it usual to use cammapping on one objet out of multible camperspectivs... for example in my scene i have additional footage of the bed from different angles... thx Quote Link to comment Share on other sites More sharing options...
hatrick Posted January 28, 2009 Author Share Posted January 28, 2009 sorry project_1.tiff Quote Link to comment Share on other sites More sharing options...
michael Posted January 28, 2009 Share Posted January 28, 2009 camera projection isn't really my bag...but I think your shader will need to support OGL to see anything in the viewport Quote Link to comment Share on other sites More sharing options...
hatrick Posted January 28, 2009 Author Share Posted January 28, 2009 here another example .... the black ore white areas should be transparent .... they do in the viewport but not after rendering seems there `s no premult while rendering... Quote Link to comment Share on other sites More sharing options...
hatrick Posted January 28, 2009 Author Share Posted January 28, 2009 i using a predefined constant from the material palette ... in my viewport i ve solved there is no problem ... the alpha channel works although it looks very crapy ... the problem is rendering thx Quote Link to comment Share on other sites More sharing options...
hatrick Posted January 28, 2009 Author Share Posted January 28, 2009 @ mrice... do you use houdini for imagebased modeling and projection ?... do you have some workflow tips for me ? thx a lot... Quote Link to comment Share on other sites More sharing options...
mrice Posted January 29, 2009 Share Posted January 29, 2009 Hi, As you said there is no premultiplication happening if you look inside the constant material from the gallery, its set up to use a separate opacity map. You can modify the material or just use a vex layered surface (change the lighting model to constant). Depending on your camera movement you might get some stretching using uv's, its generally better (but harder to initially setup) to use a camera or light to get "per pixel" mapping. There is some good info on the wiki and in some threads. Mario posted a good example a few days ago here Quote Link to comment Share on other sites More sharing options...
mrice Posted January 29, 2009 Share Posted January 29, 2009 Oh and I forgot to add that if you use the vex layered material you need to set the "Texture Tints" parameter below the map to "diff + alpha" Quote Link to comment Share on other sites More sharing options...
hatrick Posted January 29, 2009 Author Share Posted January 29, 2009 i project the plates with a camera .... and thx for info .... Quote Link to comment Share on other sites More sharing options...
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