POV-Ray : Newsgroups : povray.binaries.images : AABB reduction by Singular Value Decomposition : Re: AABB reduction by Singular Value Decomposition Server Time
15 Jul 2024 07:57:01 EDT (-0400)
  Re: AABB reduction by Singular Value Decomposition  
From: Bald Eagle
Date: 4 Apr 2021 20:25:00
Message: <web.606a5802d8cfb0ef1f9dae3025979125@news.povray.org>
"Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:

> Well done!

Thanks, but I wish I had been more rigorous in my first go-around.
I am happy that it works, but not knowing why it didn't work the first time -
bothers me.

I checked everything that I could, and even used 4-5 different online SVD
calculators to see if the numbers that came out were the same - and they were.
Which is doubly troubling   ;)

> What other uses than bounding box minimization do you have in mind for your SVD
> code ?

Well, that's a very good question.
I think that now that the proof-of-concept experiment has [finally] been
successful, the key thing will be to get a robust SVD algorithm coded in SDL,
c++ for calling from a shell-out, or for inserting into the POV-Ray source code.
Because I have no "SVD code" - it's just the application of the matrix transform
that comes out of an online SVD calculator.  (It choked on ~28,000 vertices of
an stl file)

That may take some time, although I know that I have an implementation of a
Jacobi algorithm in POV-Ray format [ :O ] bookmarked
https://stackoverflow.com/questions/10781639/how-to-compute-normal-vector-to-least-square-plane-in-povray-only

So that will be a head start.

As for other applications, I will have to think about that, since most of the
people I have contacted for assistance always commented that they'd never
thought of using it for 3D data...


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