Help with AA and tonemapping

[bigstick]

I am steadily making progress with Kray, and learning how to configure the parameters thanks to everyone's posts on the forum. I really appreciate the help and particularly so when you share your settings. So, a big "thank you" to everyone here!

2 things I do have a little difficulty understanding though, is where and when to use particular settings. AA and tonemapping are the things that most readily spring to mind. For example, what are all the various options best used for? What are the advantages and disadvantages? Which sort of scenes do pixelfilter Mitchell and Lanczos work best on? Which is fastest?

For tonemapping, I have trouble with this partly because I am colour blind. I often find that my scenes look a little 'washed out' and lack contrast. When do you tend to use exponentional, and when do you use linear? What settings do you use to improve contrast? Do you just do this in PS?

Would anyone care to elaborate on these things - please?

Another of the fascinating things is that there appear to be a lot of professional visualisers here. As a newbie in terms of high-end render engines, I struggle to understand why you do some of the things you do. I don't think there is an answer to this other than for me to keep reading and trying to learn.

[Captain Obvious]

The pixel filters basically control the sharpness / softness and how that's applied to the anti-aliasing. Lancoz, for example, is a sharpening filter. It's a bit like applying an unsharp mask filter in Photoshop or whatever. Mitchell is a softerning filter. It will make the image slightly blurry, but it will also significantly reduce noise and such, and it doesn't blur it as much as, say, a blur filter would. Mitchell is my favorite, since I normally render really high-resolution. When you render high-resolution, sharpness is a bit irrelevant.

[sepo]

Hi
I am newby as well. So what you sayin is it is Michell which makes the images blury. You say the cure is in rendering large images and I can kind of understand. Have you got any tips how to reduce blur (without PS) but not to create noise at the same time and obviously not too long render time.
Thanks

[bigstick]

Thanks, that's 2 of the five sorted out. What about box, cone, cubic and quadric?

And when do you tend to use linear, exponential and gamma tonemapping? I know that gamma tonemapping is generally used for hdr images, and that linear tends to make things a little flatter, but iseems to be best for exteriors. What sort of situations would everyone else tend to use them in.

I have attached a WIP render. The chair and table need a lot more work. The scale is a too large, the chair needs a lattice back and seat, and I need to change the materials, but gradually I'm getting happier with my results. C&C appreciated.

[Captain Obvious]

Mitchell doesn't exactly blur the image; it's a soft image filter. It's sort of like applying a blur that's smaller than one pixel. If you render for high-res print, a "blur" that small is not going to be noticible. However, it does reduce noise and aliasing artifacts, and gives it a kind of "film" look rather than the overly crisp and sharp "CG" look that's oh-so-common.

If you want the "Vray" look, just use the Lancoz or Catmull-Rom filter; it's really sharp.

The box is kind of crummy, in my opinion. It's sharp, but will often cause aliasing issues and noise and such; the cone a slightly sharp filter (but not as sharp as Lancoz); the cubic I'm not sure about; the quadric doesn't strike me as being overly useful (especially seeing how I think it's broken in OB4).

For stills, where render times aren't that big an issue, I prefer to render at higher resolution and use a soft filter, and then apply some unsharp mask on top of that. For animations, I prefer to go for a film-y kind of look and use motion blur, depth-of-field, etc, and a soft filter. Crisp and sharp doesn't always look good.

I normally render to HDR, and do my tone mapping in Photoshop.

[bigstick]

Strangely, I have been using mitchell quite a lot for precisely this reason, but without knowing eaxctly why. I'm not that keen on the glitzy sharp images personally. Thanks for the explanation>

[sepo]

Thanks for the info. Much appreciated.

[bigstick]

Any takers for tonemapping - anyone?

[jure]

Linear is the same as gamma with parameter 1.0.
Exponential is nice when you have bright light that would otherwise be blown out. Exponential will compress all those values that are above 255,255,255 so that they can be represented with 0-255 values

[bigstick]

Excellent, that is really helpful, thanks a lot Jure!