Rendering : Depth of field problems

[Arnage]

When you render a scene with DOF you can see parts that would be invisible without the dof, for example you can see some of the blue behind the letters in your picture, because it is blurred and visible at the edge of the letter, but because you use the dof rendereffect max does not render these parts so it blurs black pixels instead of the blue part behind your letters. To solve this problem you can:

- use the camera's blur option (only available in max5) (really slow)
- you could use a plugin to do it for you (but i don't know any free ones, so that'll be an expensive option)
- you could render the background and the forground seperate and blur the background the put the foreground on top of that.

Hope that helps

[jeb]

it helps a lot to use geometry as background..i encoutered the same problem one time and i used a big sphere with a sky texture in it and the jaggies of the dof effect disapeared. because the problem is that the dof effect dosnt compute very well the alpha channel, so with geometry covering your background you dont have any alpha so it renders very nice

[gaggle]

I may be blatently wrong on this one, but I've just stopped even trying to use the DoF from the effects window entirely. Always the halo problem, or some close relative to it.

It hurts rendertime wise (REALLY hurts), but the camera DoFing is pretty cool-looking. Provided you pump up the iterations.

Oh, nifty tip if you hadn't noticed: you can animate the iteration-count. Extremly timesaving when you're dealing with a DoF that only sometimes needs to have high iterations due to some wild cameramovements.

[figment]

Cheers guys. ive rendered out the model with alpha channels and comped it in after effects. it looks great.

[joconnell]

Just as an aside, your best bet for doing accurate depth of field is to use a full raytraced depth of field as available in final render, brazil or vray. The multipass version in max is fine but you need lots of samples to smooth it out and you can effectively multiply your render times by the number of samples you use (25 dof samples = re render the same image 25 times). Next option is a plugin like xdof which takes about a minute to render DOF with glowy highlights and the such. Last option is a 2d filter approach. I personally use the image lounge rack focus plugin. You can render out a depth matte from 3dsmax using this (http://www.scriptspot.com/download.asp?ID=1101) script and using it as a control layer in after effects. You use the depth information to control which parts of the image are in and out of focus.

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