[REQ] Camera Clipping

[delle]

Hi to all, as you can see from this image, I had to remove the back wall to let the camera work.

The side effect is that one part of the scene is in darkness.

I do interior rendering so I don't want to enlarge the room (the room is real and I don't want to create e fake room) nor I want to enlarge the viewing angle (placing the camera inside the room)

I propose three solutions:

• 1) Camera clipping (add a front clip plane to the camera)
  2) Add an attribute to objects (e.g. to the walls) to make them invisible to the camera but not to light scattering
  3) Add the attribute to objects "One side only" as ExitPortal are, so I can orient a plane in the direction of the inside part of the room.

Please Ono... please please please....

Delle

[CTZn]

this topic is related:

http://www.indigorenderer.com/joomla/fo ... a+clipping

I'm not sure I understood point 3, is that the "arbitrary clipping plane" thing exposed there ?

[delle]

I've post a similar request in the past (http://www.indigorenderer.com/joomla/fo ... highlight=) but nothing happened.

So I've tried again.

I'm not sure I understood point 3, is that the "arbitrary clipping plane" thing exposed there ?

No, I mean "back-face culling" (http://en.wikipedia.org/wiki/Back-face_culling)

Delle

[pixie]

Well, Indigo already take into account the position of normals it could be a step towards back face culling

[delle]

I agree (one small step for a man, a giant leap for mankind)

Delle

[dmn]

4) material :: Region
Inside
-boolean value that changes wether all other materials inside or outside the material render as null, but still reflect/absorb/emit light
intersection
-RGB value that specifies a flat color to cover any visible section cut.
alpha
-boolean value that makes the section fill transparent when cutting through transparent objects.

[dmn]

Actually, this would probably be harder than it sounds. Ono would have to come up with a way of storing all the light bounces into and out of the 'clipped' area separately from the visible area?

Or can the light multiply- when light hits the clipped surface it creates one wave that continues through and hits the viewpoint (or doesn't) and another that reflects back to the visible area and continues to bounce, until it hits a clipped surface again?

[delle]

I think that "back-face culling" is very easy to implement.

I bet that Indigo is currently able to handle such faces (see "exit portals).

So, the only thing to do is to add an attribute to meshes:

Code: Select all

<single_side>
true
</single_side>

With this small enhancement, it will be possible to place the camera outside the room and then to close the room adding a "single side wall" facing the internal part of the room... that's all folks!



Delle

[delle]

P.S. this is the final image....



Delle

[dmn]

I think that "back-face culling" is very easy to implement.

I bet that Indigo is currently able to handle such faces (see "exit portals).

So, the only thing to do is to add an attribute to meshes:

Code: Select all

<single_side>
true
</single_side>

With this small enhancement, it will be possible to place the camera outside the room and then to close the room adding a "single side wall" facing the internal part of the room... that's all folks!



Delle

I don't know. If the light is allowed to pass through the surface to the camera, then nothing is reflected and you have darkness? Wasn't that the original problem?
All exit portals do is enhance the use of environmental light sources by telling the simulation where to look for light particles.

[alex22]

But if it is single sided, the camera would look through the wall from one side, and from the other it would look normal. Depending on from which side the light comes from. The "inner" or the "outer" side of the room wall.

[dmn]

Yes But... If you don't want the light loss delle shows in his example renders, the light can't just pass through the 'culled' surface to the eye point, it has to pass through the wall And reflect back into the room to cause indirect lighting somewhere else, And then it has to reflect back through the 'culled' surface again, something like that.

Maybe a random number are allowed to pass through the surface, and a random number are reflected off, but even then you are still sucking light out of the scene?

It's just not as simple as not drawing the face when viewed from behind (back face culling)

2) Add an attribute to objects (e.g. to the walls) to make them invisible to the camera but not to light scattering

[alex22]

You could also simply split the ray in two with equal power. The one going through the wall should of course only interfere with the camera and nothing else.

[Kram1032]

dmn: Don't forget, Indigo does backward-raytracing (as long as it doesn't use BiDir, which will be the harder part to make such a feature compatible with)
The ray always starts at the cam and ends at the lightsources.
Bug-scenarios would look like this:
If there's a window, a ray of light could pass out of the room and then, on the "invisible" wall, could be relfected in again.
A wall being invisible ALL THE TIME from one side, might not be THAT hard to implement...
You'd need an additional check, if that ray already hitted the wall from that side, though, to get an at least partly realistic result. (The thing is, that cam-positionings, being made possible by that, are NEVER realistic xD)