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I'm fighting with my scene where I want to show some kind of portal. All scene has illuminated by hdri №1. The objects behind the 'glass' (object with 100% transparency) should be illuminated by hdri №2. I'm using light path node to separate two 'worlds'visually and it works (according the shadows), but object behind the glass (box) has very weak impact from his hdri. It looks like settings of transparent material somehow affected the image behind or maybe transparency of it is not 100% transparent.

I don't want use compositing for this effect because of realistic effect I'm trying to achieve, so it would be great if someone you guys could share some thoughts or links that might help

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cegaton Thank you very much for your help, advice and links! Especially for pointing at sockets colors. Now I'm digging both articles.

I changed the node tree using color mix node and set the Light Path node to Transparent Depth (and glass material set to transparent BSDF), and, unfortunately nothing has changed. :,-( The objects behind the glass now still highlighted poorly in comparsion with hdri connected straight to the output node. It looks like hdri is loosing it's light intensity in this case

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Mikman
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  • While this isn't impossible, I think you'd be better off using a separate scene with a camera from your POV and composite the two in post. – Frederik Steinmetz Jan 04 '20 at 14:56
  • Make sure that the transparent material color is fully white (1,1,1). Keep in mind also that not all HDRs were created equal... It is likely that one of them is darker, or might not be a real HDR with a wide dynamic range but an image with display referred values (0-1) in any case you can change the brightness of the environment texture with the "strength" control. –  Jan 11 '20 at 18:38
  • https://blender.stackexchange.com/questions/144520/blender-hdr-makes-objects-too-bright/144521#144521 and https://blender.stackexchange.com/questions/69605/how-can-i-create-a-silhouette-using-hdr-in-cycles/69615#69615 and https://blender.stackexchange.com/questions/113908/increase-brightness-of-hdr-to-light-the-scene-but-keeping-the-background-at-a-l and https://blender.stackexchange.com/questions/87347/how-do-i-adjust-for-overexposure-using-physically-based-lighting/87355#87355 –  Jan 11 '20 at 18:42
  • You can also use the false color view transform to evaluate the values of the "HDR" images. https://blender.stackexchange.com/questions/55859/using-the-false-color-look-in-combination-with-the-cdl-node-to-work-on-wide-dyna –  Jan 11 '20 at 18:43
  • https://blender.stackexchange.com/questions/56267/how-to-scale-properly-hdri-image-to-be-used-in-asc-cdl-hdr-render –  Jan 11 '20 at 18:45
  • But to make all of this information useful it would be better if you asked a follow-up question on a different post so that the anwers are useful to others as well. –  Jan 11 '20 at 18:46

1 Answers1

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Use a light path node and color mix node.

On the so called "portal" object use a transparent shader.

Then on the world, set the two different HDRs and use the transparent depth to control the RGB mix of the environments.

Don't use shader mix nodes to mix RGB color information. Pay attention to the color of the sockets! Green sockets should connect with green, yellow with yellow, gay with gray and so on.

Also: nodes that are not connected to the final output have no effect on the result.

Read: What is the meaning of the color of the node sockets in the node editor?

and

Cycles - (Shader) Nodes - inputs outputs - What are the exact data types?

enter image description here How this all works is

Transparent rays will use one image, all other rays (like diffuse or glossy, etc) will use the other. The limit of this solution is that glass objects (or other transparent or semitransparent objects) will need to be composited.

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