DaJuice Posted February 16, 2006 Share Posted February 16, 2006 Hi Is there any way to combat some of the problems that are introduced when you start rendering with a curved lens in mantra? Problems such as models breaking up with SDS rendering or the appearance of shading anomalies. Thanks. Quote Link to comment Share on other sites More sharing options...
symek Posted February 17, 2006 Share Posted February 17, 2006 HiIs there any way to combat some of the problems that are introduced when you start rendering with a curved lens in mantra? Problems such as models breaking up with SDS rendering or the appearance of shading anomalies. Thanks. 24794[/snapback] really sorry for trivialism, but what comes to my mind first is: stay away from such effects in rendering... I'm almost sure you know this but in case you don't... Do you need this for some special reason? Can't you do it in 2D? Or just render 1 reference frame and then mimic its curvature in post? Quote Link to comment Share on other sites More sharing options...
DaJuice Posted February 17, 2006 Author Share Posted February 17, 2006 Hmm, is it common to do the effect in post as opposed to in camera? I don't really see any advantage to doing the effect in 2D as opposed to a working 3D lens. It doesn't seem to take any longer to render and there is no chance for downgrading of quality due to resizing of the image. Also keep in mind I'm using Apprentice so I don't have that much resolution to work with and the effect is quite pronounced. Quote Link to comment Share on other sites More sharing options...
symek Posted February 17, 2006 Share Posted February 17, 2006 Apprentice is a good reason to do it in 3D In normal case, as you know, lenses artifacts are the way to compose CG with reallife footage. You have much greater control on it in 2D. As to downgrading image quality - this is of course essential - I've never met situation in which I wasn't have to apply some filter on CG element to match it to real camera picture. Always little blurry... Again, it's just a: picture = mix(CG,Real) case. cheers, symek. Quote Link to comment Share on other sites More sharing options...
deecue Posted February 18, 2006 Share Posted February 18, 2006 you can always model warped geometry and render it normally.. i've seen it done before and it works great on complex scenes that just wouldn't handle the calculations for lens distortion.. Quote Link to comment Share on other sites More sharing options...
DaJuice Posted February 18, 2006 Author Share Posted February 18, 2006 Hey, thats a great idea, never thought of it. Thanks deecue! Quote Link to comment Share on other sites More sharing options...
symek Posted February 18, 2006 Share Posted February 18, 2006 Hey, thats a great idea, never thought of it. Thanks deecue! 24840[/snapback] but how to calculate correct geo distortion? idea sound interesting... Quote Link to comment Share on other sites More sharing options...
deecue Posted February 18, 2006 Share Posted February 18, 2006 well it would depend on the shot.. i'm sure you could figure out the math behind your camera and apply it in some procedural way to your objects in the scene.. but i'm pretty sure you could get away with doing it to visual taste.. so as long as your camera is set and not moving too too much (fly throughs wouldn't work too well in this case obviously) and you knew what you were going for so just keep an eye on the final result while working and making adjustments.. i don't know if this is the best way to do it, but that's how i'd attempt it if it were me.. although figuring out how to do it procedurally does sure sound interesting now that i think about it.. maybe i'll give that a whirl one of these days when i have a moment.. Quote Link to comment Share on other sites More sharing options...
peliosis Posted February 18, 2006 Share Posted February 18, 2006 Perhaps the easiest way would be save the whole shot out frame by frame in bgeos, reimport and apply transformation to it. I never heard of troubles using lens effects. I used it to some extent in mental ray. Quote Link to comment Share on other sites More sharing options...
DaJuice Posted February 18, 2006 Author Share Posted February 18, 2006 The way I'm doing it at the moment is with the Lattice SOP. The control cage besically engulfs the small scene, but I take the back of it and move it waay back towards the horizon (after orienting the cage along the camera). Now I can deform the front of it (shape it from a grid into a bulged, circular shape). I copy the normals from the pre-deformed geo, and use the Rest SOP for any procedural patterns that I might want to use. It's working well so far, and you get a good deal of control. Don't know how correct it is, but it's great for eyeballing. Quote Link to comment Share on other sites More sharing options...
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