<p>You can use single sided triangles for the ceiling so that they are pointing towards the room. This way the ceiling influences the GI in the room but you can see through it when observing from outside</p>

CC BY-SA 3.0
2016-11-02T01:31:01.763Z
2016-11-02T01:31:01.763Z
JarkkoL
<p>I am doing renders of the inside of a room. I would like to show a "bird's eye" view of the room, from above the ceiling (outside the room), but still see the interior of the room.</p>

<p><a href="https://i.sstatic.net/F240t.jpg" rel="noreferrer"><img src="https://i.sstatic.net/F240t.jpg" alt="birds eye view"></a></p>

<p>An easy way of doing this is to simply hide or remove the ceiling surfaces. However, this has the side effect of reducing the amount of lighting in the scene, because the ceiling no longer reflects light into the room. The top corners and edges of the walls also are no longer lit accurately.</p>

<p>I would like to render the scene <strong>as if</strong> the ceiling was there, but without the ceiling actually being (directly) visible.</p>

<p>Is there a name for this problem, a technique, or material?</p>

CC BY-SA 3.0
2016-11-02T12:04:34.873Z
Lighting a scene and final rendering the lit triangles are orthogonal.
ratchet freak
CC BY-SA 3.0
2016-11-03T09:14:44.753Z
Like, at a right angle to each other? Dude that is deep.
aaaidan
CC BY-SA 3.0
2016-11-03T09:20:12.143Z
No I mean that once you have the lighting information you can simply leave out the ceiling geometry in the final render of the lit scene.
ratchet freak
<lighting><global-illumination><material>
Is there a material that contributes to GI, but isn't directly visible?
aaaidan
# Is there a material that contributes to GI, but isn't directly visible?

(Asked by: username_0 on 2016-11-02)

I am doing renders of the inside of a room. I would like to show a "bird's eye" view of the room, from above the ceiling (outside the room), but still see the interior of the room.

[![birds eye view](https://i.sstatic.net/F240t.jpg)](https://i.sstatic.net/F240t.jpg)

An easy way of doing this is to simply hide or remove the ceiling surfaces. However, this has the side effect of reducing the amount of lighting in the scene, because the ceiling no longer reflects light into the room. The top corners and edges of the walls also are no longer lit accurately.

I would like to render the scene **as if** the ceiling was there, but without the ceiling actually being (directly) visible.

Is there a name for this problem, a technique, or material?

**Tags:** lighting, global-illumination, material

> **Comments:**
> **username_1**: Lighting a scene and final rendering the lit triangles are orthogonal.  
> **username_0**: Like, at a right angle to each other? Dude that is deep.  
> **username_1**: No I mean that once you have the lighting information you can simply leave out the ceiling geometry in the final render of the lit scene.  

---

## 1 answers

### Answer by username_2 on 2016-11-02. Score: 5 | Accepted answer

You can use single sided triangles for the ceiling so that they are pointing towards the room. This way the ceiling influences the GI in the room but you can see through it when observing from outside


---

