POV-Ray : Newsgroups : povray.newusers : Camera position for spline object : Re: Camera position for spline object Server Time
5 Jul 2022 04:51:32 EDT (-0400)
  Re: Camera position for spline object  
From: Tor Olav Kristensen
Date: 26 May 2022 10:20:00
Message: <web.628f8bb0c5341975afe6ae3e89db30a9@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:
>
> > Hehe, there you tempted me to have a look at this.
> >
> > I opened the screenshot in gimp and copied the 3 axes around to check if the
> > camera used could be a orthographic camera. It seems so.
>
> Ah. It didn't seem to be a purely perspective view, but it was early and I was
> heading out.  It certainly had that "view-camera corrected film-plane" look, if
> you know what I mean.
>
> Perhaps some of the work done with Norbert Kern's 'Position-Finder' tool could
> be used to back-calculate points for the spline to get something that more
> closely resembles the posted 3rd-party software graphic.

I've now hat a look at his macro. It seems that what it could be used for in
this case, is to calculate the coordinates of the corners of the box projected
onto a plane.

But the same could be achieved with less work by loading the image into e.g.
Gimp and then finding the coordinates of the corners within the cameras view
plane.

From these coordinates, it may be possible to solve several equations with
several unknowns to find the possible camera vectors.


> .... or the original data set could be posted.   ;)

Yes.
But I'm now wondering if the original poster used another spline type in the
other tool. The spline type in the POV-Ray code is "b_spline". But I've not been
able to find out what spline type that is supposed to be. I very much doubt that
it is the B-splines described here:

https://en.wikipedia.org/wiki/B-spline

Perhaps the b stands for Bezier (?) Maybe someone can verify this...

--
Tor Olav
http://subcube.com
https://github.com/t-o-k


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