POV-Ray : Newsgroups : povray.bugreports : sphere slicing problem : Re: sphere slicing problem Server Time
1 Dec 2021 17:21:19 EST (-0500)
  Re: sphere slicing problem  
From: jr
Date: 1 Nov 2019 10:20:01
Message: <web.5dbc3e2e401c5809feeb22ff0@news.povray.org>
hi,

William F Pokorny <ano### [at] anonymousorg> wrote:
> ... This means for
> you, you'll have both coincident (sometimes wrongly ordered)
> intersections and ones less and less likely to align with the
> orthographic camera rays as the sampled surface becomes parallel to the
> ray. Such rays, if they hit, would be near tangents to the surface - the
> shortest of these tends to get filtered in many objects too for a few
> reasons.

the image posted in p.b.misc shows a lo-res Y-axis scan, orthographic camera on
the left, perspective on the right.  and the 'surface becomes parallel' thing is
clearly where expected on the left.  I cannot fathom though why for the
perspective camera the problem manifests above "the bulge" instead of the
centre; cameras in both stationed directly above the sphere.

I now think that if, perhaps, there is a relatively simple and accurate way of
calculating camera parameters for both camera types such that the object is seen
in exactly the same size/position, perhaps one could merge the results.  any
thought(s) welcome.

I also find the patterns appearing in many of the sliced rings interesting, the
regularity of the spacing etc holds information -- I just can't .. parse it. :-(
 if anyone's interested I can post the frame/slice images.


regards, jr.


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