Hide a wall but keep the light bounced

bronyswvg

I work on a scene that takes place inside an apartment. Since the space is very limited due to size of the apartment i want to hide the wall to make room for a camera. I don't want to use wide angle lens. When I click hide the wall stops bouncing the exterior light which is quite logical and it makes my scene too bright. Is there any way to hide the wall or make it invisible to the camera but keep the light bounced as if this wall was still visible? 

crosswind

I'm afraid there's no such a way to keep lights bouncing with the wall hidden (or hidden by a section plane, etc). You interior turning too bright is just because the light from HDRI or external light sources pass thru the hidden wall. You can just reduce the value in Environment Map in Render Settings, or simply use Scene Only as Environment Mode.

Elor

You don't need to hide the wall: you can use an Iray Section Plane which will allow the camera to see through the wall (an ISP let the light passing through it in one direction but not in the other, so you may have to play a bit with it to get it in the correct orientation).

You can create one one manually following this tutorial:

https://www.deviantart.com/slimmckenzie/journal/Tutorial-Iray-Section-Plane-Node-beginner-661286658

Parenting a small plane set to only be visible in Viewport (and invisible in render) to the Section Plane should make it easier to place it where you need it.

Camera Cutaway (maybe other products are able to create one too) has Scene Cutaway tool which create a Section Plane:

https://www.daz3d.com/camera-cutaway

This promo render will explain what they can do:

barbult

crosswind said:

I'm afraid there's no such a way to keep lights bouncing with the wall hidden (or hidden by a section plane, etc). You interior turning too bright is just because the light from HDRI or external light sources pass thru the hidden wall. You can just reduce the value in Environment Map in Render Settings, or simply use Scene Only as Environment Mode.

Isn't that exactly what the Clip Lights parameter on the Iray Section Plane is for?

• When Clip Lights is set to On, the section plane will make the wall invisible, but the exterior light will be prevented from entering the enclosed area. Only the lights inside the enclosed area will be visible in the render. 
• When Clip Lights is Off, the exterior light is allowed to enter the enclosed area via the "opening" created by the Iray Section Plane. Both the lights inside the enclosed area and the exterior lights will illuminate the inside of the enclosed area.

Note: The Iray Section Plane should be inside the enclosed area, so geometry behind it (the wall that is in your way) will be hidden from the camera. The camera should be outside the enclosed area, where you would normally see only the exterior wall, if there were no Iray section plane.

Richard Haseltine

The trick is to turn on Clip Lights in the Parameters for the Section plane - then it can be seen through, but the hidden elements will still affect lights (and will still show in relfections).

barbult

Here is an example. I created a primitive plane 5M in size and put a textured metalic shader on it. I put a G9 Dev Load character inside and on point light inside. I added an Iray Section plane inside and a camera outside. The Iray Render Settings environment was a bright rust toned HDRI from Dimension Theory.

Clip Lights On

Clip Lights Off

crosswind

barbult said:

crosswind said:

I'm afraid there's no such a way to keep lights bouncing with the wall hidden (or hidden by a section plane, etc). You interior turning too bright is just because the light from HDRI or external light sources pass thru the hidden wall. You can just reduce the value in Environment Map in Render Settings, or simply use Scene Only as Environment Mode.

Isn't that exactly what the Clip Lights parameter on the Iray Section Plane is for?

• When Clip Lights is set to On, the section plane will make the wall invisible, but the exterior light will be prevented from entering the enclosed area. Only the lights inside the enclosed area will be visible in the render. 
• When Clip Lights is Off, the exterior light is allowed to enter the enclosed area via the "opening" created by the Iray Section Plane. Both the lights inside the enclosed area and the exterior lights will illuminate the inside of the enclosed area.

Note: The Iray Section Plane should be inside the enclosed area, so geometry behind it (the wall that is in your way) will be hidden from the camera. The camera should be outside the enclosed area, where you would normally see only the exterior wall, if there were no Iray section plane.

You're right ~ I think I misunderstood what is needed from OP... I only thought about ray length of lights bouncing on that "hidden wall" ~~