Le 2020-02-03 à 10:30, Francescodario Cuzzocrea a écrit :
> 
> 
> 
> Hello !!
> 
> I'm a Master student in Space Engineering in Politecnico di Milano.
> 
> I'm using POVRay for my master thesis project and I was really impressed by
> POVRay rendering capabilities.
> 
> Specifically, I'm using POVRay to generate images of a spacecraft in random
> position into a generic orbit, which subsequently I'll analyze with different
> computer vision algorithms to try to recognize the spacecraft into the scene.
> 
> The spacecraft has first been modeled with Autodesk Inventor, then it has been
> imported into Blender to exploit the POVRay addon for Blender capability to
> generate directly generate POV code.
> 
> The POV blender code was then manipulated in order to obtain a .inc file
> containing the "spececraft" object, which is assembled by the "merge"
> (https://gitlab.com/bosconovic/spacacecraft-pov/blob/master/satellite.inc#L158)
> of the different spacecraft mesh2 components.
> I did the merge in order to be able to simply call the "spacecraft" object in my
> pov
> file and place it into the scene, with the ability to rotate and translate it by
> simply manipulating the object's attitude\position matrix (which is randomly
> generated) :
> https://gitlab.com/bosconovic/spacacecraft-pov/blob/master/tango_102.pov#L24 .
> 
> The issue is that, sometimes, for certain combination of spacecraft\camera
> relative position the spacecraft it is not entirely rendered, and I cannot
> understand why.
> 
> Here two pictures of the problem :
>   - https://gitlab.com/bosconovic/spacacecraft-pov/blob/master/tango_102.png
>   - https://gitlab.com/bosconovic/spacacecraft-pov/blob/master/tango_30.png
> 
> In the first one almost half of the spacecraft is cutted, in the second on the
> left a piece of the solar panel is cutted.
> 
> Can anyone help me out to understand what I'm doing wrong ?
> Here is the POV source I'm using along with the Blender model :
> https://gitlab.com/bosconovic/spacacecraft-pov
> 
> This is the command I use to generate the images : povray tango_102.pov +H1200
> +W1920
> 
> 
> 
> 
If you had used an orthographic camera, that would be expected for any 
part that are behind the camera, but your sample files are using the 
default perspective camera.

Using an union instead of a merge is more effecient and render faster. 
The merge is intended for transparent compound objects where internal 
surfaces should not be visible.

In your case
#declare Space_Craft = merge{...}
and
#declare Space_Craft = union{...}

Will give you the exact same end result, but the second will render faster.

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