OTOY Forums

I think I`m doing something wrong, but I can`t get two passes to combine properly like it should according to the how-to: http://render.otoy.com/forum/viewtopic.php?f=51&t=44350
in PS i have:
1 ambient pass
1 lightpass

when adding linear dodge the image becomes too bright, i need to change the fill value for correction?
i saved out 16-bit pngs and kernel with PT

Hi,

What are your imager settings? You need to make sure you are working in linear color space. Can you try to set your gamma to 1 and the response to Linear/off? This should add up in post (you need to gamma correct the image in Photoshop afterwards because otherwise it will look too dark.).

cheers,
Thomas

changed the gamma to 1 in standalone + linear response, it get`s better, but it`s too bright when combining them in ps (cs4)
do i need to change exposure to 2.2 in standalone?

Use 'Screen' blending mode on 16bit images. Use 'Add' on 32bit.

yep that does the trick! thanks!

hi stratified,

Does changing the opacity in post of an extra lightpass equal more or less physically correct changing the power of a lightsource?
i`ve been looking into this and it kind of works to tweak / balance light, im just not sure if it`s physically correct

cheers

whersmy wrote:hi stratified,

Does changing the opacity in post of an extra lightpass equal more or less physically correct changing the power of a lightsource?
i`ve been looking into this and it kind of works to tweak / balance light, im just not sure if it`s physically correct

cheers

The formula is total light = C1 * L1 + C2 * L2 + ... + Csun * Lsun + Cambient * Lambient. Tweaking Ci modifies the power of the light. But I don't think you need to change the opacity of the layer (maybe I'm wrong). I will have to try later with PS but I tried this experiment in Blender and there I had to use the gain on the color correction node.

cheers,
Thomas