POV-Ray : Newsgroups : povray.bugreports : sphere slicing problem : Re: sphere slicing problem Server Time
27 Oct 2021 00:31:57 EDT (-0400)
  Re: sphere slicing problem  
From: jr
Date: 4 Nov 2019 14:50:11
Message: <web.5dc07ff0401c5809feeb22ff0@news.povray.org>
hi,

William F Pokorny <ano### [at] anonymousorg> wrote:
> On 11/3/19 1:31 PM, jr wrote:
> > yes, 'df3util' can import PNG, either as grayscale or _one_ of RGBA, so I don't
> > see/use colours at that stage.  :-(  still, I'd like to understand better the
> > way you outlined in the previous post, ie using a third cam to post-process the
> > two perspective cams slices (iiuc).
> ...
> What I had in mind was to create two pigments which are planar image
> maps of say sliceDown00.png and sliceUp00.png, respectively. Call these
> PigDown and PigUp. (You might need to rotate/scale to align with the
> final orthographic camera - max_extent() can grab the input image x,y
> size)
>
> Wrap these two pigments in functions (only way they'll get used):
>
> #declare FnDown = function { pigment { PigDown } }
> #declare FnUp = function { pigment { PigUp } }
>
> Use these in the use_defined the PigmentMaxUpDownPerspective I mentioned
> previously and use that texture with ambient 1 or emission 1 (diffuse 0
> use no lights) to texture a plane. Place this plane in front of an
> orthographic camera and render to get your real sample taking the max
> r,g,b values for each pixel from the down, up slices. This third render
> is your slice00 sample.

a fair amount of work + organising but (gut feeling) up + down combined ought to
catch 100% of the info.  (perhaps even at slightly less insane quality settings
than used now. :-))  I need to work out real detail[*] but think two template
scenes and three ini files should cover it.

[*] pen + paper.  :-)

> Here we are using POV-Ray as an image processing
> tool. Something at which it's very good - if not as fast as dedicated
> image processing tools.

lack of speed is a drawback during development, but hey..

> FYI. There might be typos in my SDL, I didn't set up a small scene as I
> often do.

I'm glad you're giving such detailed advice + feedback, and will probably need
more in a few days time.  :-)  thanks.


regards ,jr.


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