On Mon 24/09/12 22:27, H. Karsten wrote:
> scott <sco### [at] scottcom> wrote:
>>> If PovRay would be able to export it's geometry as .stl files, using one of the
>>> methods used like in the old patch (like "tessel" or "tesselate", using one
>>> PovRay-unit as one millimetre), I'm very sure it will be used in wide areas of
>>> 3D-Printing.
>>
>> It might be worth checking if the 3D printer can accept a series of
>> bitmap slices directly, this would be very easy to generate from POV and
>> probably more accurate.
>
> This step would need to be done insight the slicer-package. Not a bad idea so
> far!
>
> Slic3r for example cam slice objects into a .png sequence... funny, and I always
> asked myself what this is good for.
>
> So there would need to be just the other way around.
>
> One problem so far is, that when you tell the slicer the thickness of the
> slices, the amount for the filament transport needs to be calculated too.
> As well you are not allowed to have thicker slices as the diameter of you
> filament.
> As long as you have all this dependencies regulated insight just one application
> live is easy.
> Using pictures as slices to print means, you need exactly to know, what you are
> doing! Do the right steps for the slices insight PovRay, put in the value in
> sclic3r and go from there...
>
> Not a task for newbie's!

OK I'm not familiar with the inner-workings of 3D printers, I've only 
ever sent STEP files from CAD software. I just assumed they used some 
special software to cut it up into slices before sending to the printer 
to print each layer.

> Having the objects as STL files would make live easy,

The problem is that POV in general does not use meshes to represent 
objects, so to create a file like STL you need to use some kind of 
tessellation algorithm, which is not trivial.

If there is no way to feed directly the bitmaps to the printer then I 
would be tempted to write a very simple tessellation algorithm that 
wrote out cubes to an STL file - the syntax looks quite easy for POV to 
output http://en.wikipedia.org/wiki/STL_(file_format)

 > leaving a sight, that
> slicing objects in PovRay can become a difficult task. For example slicing a
> mesh, or mesh2 object. Not everything can easily be used in CSGs!

If you have a mesh that is not closed properly then the 3D printer is 
going to have the same problems knowing which side is in or out of the 
solid.

 > As well you
> need to have absolute exact camera-settings, to keep everything the right
> proportions - keep in mint: all what comes with the image-sequence are pixel (or
> voxel) no mm or inches.

That shouldn't be difficult to do, after all the STL format doesn't 
appear to come with any units either.

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