Hide background but get same lighting effect?

mike9

I would like to render with iray a person who is inside a room with the room invisible. The person should have the same lighting effects (look the same) like when the room would be visible.

I can select the room and set in Parameters->Display the "Visible in Render" or "Visible" to off but this changes also the lighting for the person. Another method I tried was to render two images one without the person and one with. Then with an image editor I tried to create a difference image but the problem is the pixels aren't the same with iray because the calculation stops with the image being good enough but not pixel perfect.

Is there any option to make something transparent in daz but still have the rest look like the transparent element would be there concerning the lighting?

Richard Haseltine

Instead of trying to doa  full render without the room, just render anything with the same camera view (keep the lights as simple as possible) and, if you are using Iray, Draw Dome and Draw Ground set to Off in the Environment group of render Settings. Save that as PNG or Tiff and use its alpha channel to select teh figure from your real render - though you will still have colour contamination in translucent areas and around the anti-aliased edges to clean up. If you are using iray another option is to use Canvasses, in the Advanced tab of render Settings, and create a new Beauty Pass layer with just the figure you want to render.

mike9

The canvas looks like what I want but everything gets darker with it. Here is a test render with a new scene and only the figure+clothes in it. How it looks normally:

How it looks with canvas active:

Doesn't this work with some lights? I use the camera with headlamp set off and no light source in the scene beside the environment hdri.

Canvas settings are the following with the node having everything selectable selected (which is only the figure+clothes):

Richard Haseltine

Is that the exr file? If it is did you adjust its tone mapping (regardless of what you did to the render settings group of the same name)?

FilthyAppetite

I dont know if it would work, but I would try this.

Make complete scene, hide character, render image in IBL resolution, 

hide room, unhide character, set environment to rendered IBL image, 

I noticed that when you have an environment image loaded, but dont use draw dome, and use dome only lighting.. it gets the IBL lighting. 

So maybe that would work for you.

mike9

Richard Haseltine said:

Is that the exr file? If it is did you adjust its tone mapping (regardless of what you did to the render settings group of the same name)?

If exr is equal to hdri: the hdr shouldn't look so dark. The first one is how it looks when rendered with iray and no canvas set. The second one is the result with canvas and the settings from the third screenshot. I tried a different hdr from this package: http://www.daz3d.com/iradiance-hdri-variety-pack-one but got the same result:

Without canvas active:

With canvas active:

Tone mapping is the same for both.

FilthyAppetite said:

I dont know if it would work, but I would try this.

Make complete scene, hide character, render image in IBL resolution, 

hide room, unhide character, set environment to rendered IBL image, 

I noticed that when you have an environment image loaded, but dont use draw dome, and use dome only lighting.. it gets the IBL lighting. 

So maybe that would work for you.

The last one didn't but the images in this post have both active dome. I didn't change anything between the two beside setting the canvas with the above settings (beauty, alpha checked and everything active in the node list).

mike9

It looks like this is a bug from 4.8? For the same scene file it works in 4.9 without changing anything but doesn't in 4.8. Well I had no plans to switch to 4.9 because of the different look of skin.

I will try to use the alpha channel method suggested first. Should be ok if its not to much extra work.