On 12/2/2011 1:44 AM, Le_Forgeron wrote:
> Le 02/12/2011 00:06, Patrick Elliott a écrit :
>
>> See, my thinking here is that you:
>>
>> 1. Create your object.
>> 2. Make a "merge" copy of it, so its only got outer surfaces.
>> 3. Place that, with "no image" over the same place as the camera.
>> 4. Resize, or, if needed, build a slightly bigger version of the same
>> thing, as a mirror.
>>
>> Then you do two passes. First pass produces a displacement map, as per
>> the scuplty, which could be converted to a mesh object, fairly
>> trivially. Second pass includes textures, and maybe addon bits of
>> things, screws, panels, etc., which add finer detail, but don't need to
>> be "real", that a pure texture can't, tacked onto the surface of your
>> "no image" copy (also no-image). In principle, the result should be both
>> a mesh object, once converted from the displacement map, which you can
>> adjust a bit, as needed, and a texture, which exactly matches the
>> contours of the object you are applying it to.
>>
>> Am I off my rocker thinking about doing such a thing, or not?
>
> I get lost at the first pass and the displacement map. (which is a known
> concept, but is not part of povray's concept, IIRC)
>
> Might I assume that the "object" in 1 is globally convex ?
> Would a menger's sponge still qualify ?
>
> As I understand so far, you want to image-map a texture on your object O.
> To generate such image-map, I would do something like:
>
> 1. spherical Camera inside object O. Object O is hollow, no_image,
> textured with a basic pattern and using only ambient light, or so.
> 2. Put a sphere mirror at the camera, with a radius large enough to
> avoid hitting object O. sphere is hollow, no_reflection (save on
> rendering time).
> 3. Render the image P
>
> 4. new scene: Object O is textured with image P (map_type 1). place
> camera and lights as needed, as well as other environments.
>
> Iteration on step 4 with image P going into gimp/photoshop for details
> of texture/pigment.
>
> You could replace the spherical mirror with a vertical cylindrical
> mirror if using a cylindrical camera (type 3) and map_type 2 (as long as
> you do not have any surface parallel to the horizontal plane in object O)
>

Uh, well, already used things like a spherical camera to do bits of it, 
but, lets try this again..

The idea is to take a baseline object, say, a chair, and use three 
copies of it. One copy is hollow, and reflective, but scaled larger. The 
second is the object, with a texture applied. The third is a camera, 
with the same shape. The idea being to do something that combines these 
two concepts:

http://www.ignorancia.org/en/index.php?page=mesh-camera

Section on "texture baking", with the pre-pass, doing this:

http://johannahyacinth.blogspot.com/2007/05/sculpted-prims-with-pov-ray.html

I had to force a stop load on the page. Seems Google's system is 
misdirecting services you are logged into through their mess right now, 
resulting in blogger.com loading Youtube instead, almost immediately 
after the page loads. Maybe turning off scripting would stop it, or 
something...

In any case, the first pass is to create a larger, more detailed "color 
map", such as what the sculpties use. Since a sculpty is just a fixed 
set of points, that are "displaced" based on the color in the image, it 
follows that you could, just as easily, use that data to generate a mesh.

The second pass would include any extra objects you want to add, to 
"flesh out" the texture, since it would make as part of the final "flat" 
image, which you are going to apply to the mesh, as well as any textures 
you want to apply (mind, not including reflection, and the like, since 
that would mess with the mirror we are using to get the result, though.. 
would having the mirror produce no image mean you don't get the 
reflected result either? I think so, but I am not sure.)

The idea being to use POV-Ray to produce "both" the displacement map, 
which is to be converted to mesh, and the "UV texture", which will be 
applied to it. I know you could do it with a Mesh_Camera, as per the 
first site, but that still means building the original mesh in something 
else, and importing it, instead of doing the whole thing in SDL.

Hopefully that is clearer.

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