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Simen Kvaal <sim### [at] student matnatuiono> wrote:
> See (small) image in p.b.i. for visual impression.
>
> I am trying to model air-bubbles in water, and ran across this problem:
> Exactly _how_ does one model the camera _in_ water, viewing bubbles of
air?
> At first, I thought maybe place the camera inside an object with ior about
> 1.33 (water), then add objects (bubbles) with ior about 1.01 (air). That
> produced weird results, however exactly the same as the second method.
>
> The second method was using the law pysics: The ior is relative, I
thought,
> therefore, light passing from air into water, where air has (absolute) ior
> 1.01 and water (absolute) ior 1.33, would give a relative ior of 1.33/1.01
> (water/air). When light passes from water to air, OTOH, we will get a
> relative ior of 1.01/1.33, so I simply placed camera in space, and let the
> bubbles have ior 1/1.33. That gave me exactly the same results as before.
It
> seems iors below 1 is not allowed, judging from the image I get.
>
> The scene is really simple. A checkered plane with inverse applied to
place
> camera outside it. (Removing inverse places the camera inside, ie into the
> water.) The sphere is just that; a sphere.
>
> I've tried several combinations; all giving more or less the same results:
> *Difference between (water-)box and sphere.
> *Difference between (water-)plane and sphere.
> *Sphere inside box.
> *Sphere inside plane.
>
> Any suggestions?
My instinct would be to difference the bubbles out of the water, which has
an ior, and also to place the camera *inside* a bubble (or rather, an
air-filled lens), e.g.:
difference {
plane {y, 0 texture {WaterSurfaceTexture}}
object {UnionOfBubbles}
sphere {0, 0.01 pigment {rgbt 1} translate camera_location}
interior {ior 1.33}
}
This way, a ray is bent after it leaves the camera, then bent back when it
enters a bubble (or exits the surface of the water). I haven't tested it,
but hopefully this will give you the effect you're after...
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