ambient occlusion within closed box

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ambient occlusion within closed box [solved]

i have a room created from a box primitiv. flipped normals of box, added materials and textures, uv unwrap and one ambient light to scene.
added radiosity to camera.

i wanted to have ambient occlusion darken the corners of the room in addition to where objects are, but it does not work inside the room.
it works fine outside or if i remove the top face of the room.

can i get ambient occlusion within a flipped box somehow or do i need to fake it with a lot of lights?

any suggestion how to get ambient occlusion working with a room like this?

thx.
 
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why not use radiosity instead of ao ?
you`ll need another light source than one ambient, but that's how it works in reality as well, a closed room without a light will be dark, if you want to have it bright you need to make a decision where to put the light :smile:

- archie
 
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update

a box with a big area light under the ceiling, rendered with radiosity:

Ohne Titel.jpg
 
thx archie, radiosity works but ao would have been faster to use and closer to the visual effect i wanted to get.

there are quiet a few rooms like the one described in my scene and setting up well done lights for all of them is time consuming.

is there a way to flag the top face of the room to make light pass thru?
new material with full opacity? what about the direction of the normal?
then i could make top and bottom face disappear for separate renderings and combine the textures later.
 
thx for the example.
the visual effect i wanted to get... no lights visual just ao. the white area generated from the light is what i do not want.
 
i don't think that's possible.
you can assign a render tag to an object with *visible in radiosity* disabled, but then that object will also be invisible in diffuse, so you have the same effect as if it was deleted (reflections and emissive will remain, so that is useful with glass).
so you could stay with removed tops and make the camera background color mimic a ceiling color or you would have to make all tops separate objects (split tool) so you can attach the above mentioned render tag and then try to fake the ceiling with a texture in the emissive channel, but that would be more time consuming than the use of radiosity imho.

for the white reflections, those result mainly from the specular of the default material, a wall material with no specular and a point light with big radius instead of area (volumetric scattered samples) will help reducing the white spots.

- archie

Ohne Titel2.jpg
 
Hi.
All I have in this scene is a radiosity tag with default AO settings - except max ray lenght is set to 1.
No openings in the walls - yes I´m surprised too.:mrgreen:

Cheers
Frank
 

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@frank: interesting.

i can not reproduce your setup. i am working with cheetah3d 5.5.

no light in scene will use auto light of camera which still produces the white spot i do not want. auto light off will produce only back. adding ambient light will render all grey. all at radiosity at default settings ao. switching to radiosity will lighten up scene more but not remove white spot.

does your cam have the auto light on? any other light source in scene? how did you create the outer box?
could you post the scene?
 
got it working! thanks a lot.

problem: make ambient occlusion work within a closed room without using lights.

summarizing solution: no lights, disable autolight of camera, change ao *max. ray length* < box size (fine tuning possible)
 
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