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From: Bald Eagle
Subject: Re: Raytracing page[s]
Date: 12 Jul 2017 17:20:00
Message: <web.59665973b085b44bc437ac910@news.povray.org>
http://robertinventor.com/cubeetc/


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From: Bald Eagle
Subject: Re: Raytracing page[s]
Date: 17 Jul 2017 14:10:01
Message: <web.596cc498b085b44bc437ac910@news.povray.org>
Modeling of folded paper pop-up cards:
http://cs.smith.edu/~jorourke/DTS/Sum05/WebPages/Ana/Ana.htm

(I'm envisioning a [set of] macro[s] to take a flat object and two planes and
connect them so they fold properly)


I was looking to see if anyone had already written any formulas or macros in SDL
for dealing with matrices ... no luck so far, but I did find this:

https://people.cornellcollege.edu/dsherman/visualize-matrix.html


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From: Mr
Subject: Re: Raytracing page[s]
Date: 17 Jul 2017 14:55:00
Message: <web.596ccef3b085b44b16086ed00@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> Modeling of folded paper pop-up cards:
> http://cs.smith.edu/~jorourke/DTS/Sum05/WebPages/Ana/Ana.htm
>
> (I'm envisioning a [set of] macro[s] to take a flat object and two planes and
> connect them so they fold properly)
>
>
> I was looking to see if anyone had already written any formulas or macros in SDL
> for dealing with matrices ... no luck so far, but I did find this:
>
> https://people.cornellcollege.edu/dsherman/visualize-matrix.html

This is very specific and interesting, so sorry if the following is more
peripheral to what you ask, but maybe you should know that
the latest builds of Blender now feature an addon to create paper toys (but
rather patrons to cut, fold and glue as a volume than precut shapes that unfold
into one)


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From: Stephen
Subject: Re: Raytracing page[s]
Date: 17 Jul 2017 17:20:11
Message: <596cf1cb$1@news.povray.org>
On 7/17/2017 3:07 PM, Bald Eagle wrote:
> Modeling of folded paper pop-up cards:
> http://cs.smith.edu/~jorourke/DTS/Sum05/WebPages/Ana/Ana.htm
>
> (I'm envisioning a [set of] macro[s] to take a flat object and two planes and
> connect them so they fold properly)
>
>
> I was looking to see if anyone had already written any formulas or macros in SDL
> for dealing with matrices ... no luck so far, but I did find this:
>
> https://people.cornellcollege.edu/dsherman/visualize-matrix.html
>
>
Matrices pithed my brain almost 50 years ago. They do the same today. :)


-- 

Regards
     Stephen


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From: Bald Eagle
Subject: Re: Raytracing page[s]
Date: 17 Jul 2017 20:05:01
Message: <web.596d179eb085b44bc437ac910@news.povray.org>
Stephen <mca### [at] aolcom> wrote:

> Matrices pithed my brain almost 50 years ago. They do the same today. :)

I enjoyed this series, and you'll especially like the introductory quotation  ;)
 :D


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From: Norbert Kern
Subject: Re: Raytracing page[s]
Date: 18 Jul 2017 09:40:01
Message: <web.596dd6bdb085b44bb1f1ce6f0@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
>
> It would make a fun (and probably quite extensive) thread to post the results of
> searching even only the terms:
> XYZ's Raytracing Page



Nice idea,
here are some more resources -

http://louisbel.free.fr/scenes/scene000.shtml
https://code.google.com/archive/p/spirals/
http://asti.vistecprivat.de/
http://k3dsurf.s4.bizhat.com/k3dsurf-ftopic30-0-asc-45.html
http://www.codeworx.org/povray.php
http://www.asahi-net.or.jp/~nj2t-hg/

Norbert


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From: Norbert Kern
Subject: Re: Raytracing page[s]
Date: 18 Jul 2017 11:55:00
Message: <web.596df6a0b085b44b9eae0ff80@news.povray.org>
"Norbert Kern" <nor### [at] t-onlinede> wrote:

> Nice idea,
> here are some more resources -
>
> http://louisbel.free.fr/scenes/scene000.shtml
> https://code.google.com/archive/p/spirals/
> http://asti.vistecprivat.de/
> http://k3dsurf.s4.bizhat.com/k3dsurf-ftopic30-0-asc-45.html
> http://www.codeworx.org/povray.php
> http://www.asahi-net.or.jp/~nj2t-hg/


forgot some...

https://commons.wikimedia.org/wiki/Category:Images_with_Povray_source_code
https://code.google.com/archive/p/spirals/source/default/source?page=4


Norbert


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From: Kenneth
Subject: Re: Raytracing page[s]
Date: 18 Jul 2017 23:45:01
Message: <web.596e9d22b085b44b883fb31c0@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:

>
> I was looking to see if anyone had already written any formulas or macros in SDL
> for dealing with matrices ... no luck so far, but I did find this:
>
> https://people.cornellcollege.edu/dsherman/visualize-matrix.html

Thanks for posting this link. I need as many sources as I can find, to help me
further understand how a matrix works, and its many uses. (I *probably* learned
the fundamentals in either high school or at university...but which I've long
since forgotten, as I never had occasion to put it to use-- until I discovered
POV-ray. For example, the real magic of Rune's ILLUSION.INC include file lies in
his use of a matrix, with amazing results. I'm still trying to understand what
he did!)


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From: Bald Eagle
Subject: Re: Raytracing page[s]
Date: 19 Jul 2017 12:05:01
Message: <web.596f49fdb085b44bc437ac910@news.povray.org>
"Kenneth" <kdw### [at] gmailcom> wrote:

> Thanks for posting this link. I need as many sources as I can find, to help me
> further understand how a matrix works, and its many uses.

Well, I'm sure there are many different types of matrix - and the graphics /
camera / projection matrix is a special application.

>For example, the real magic of Rune's ILLUSION.INC include file lies in
> his use of a matrix, with amazing results. I'm still trying to understand what
> he did!)

Just by taking a quick look at the code, (I've never used it, and the sample
file output makes no sense to me) I'd have to say that it just takes a "flat"
image and skews it - stretches it - so that it fits / lines up correctly with
the field of view from the camera position - a perspective correction.

This is also something I need to look into, and have only briefly played with it
to correct some perspective distortion of photographed flat surfaces.

I'm sure it could be harnessed to do some basic photogrammetry, if I ever live
that long, have enough round tuits, and triple my caffeine intake.  ;)

Glad you can use the link - it looked like a good one.   Lohmueller of course
has some examples on his page[s] as well, and many examples are available via
the insert menu.


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From: Stephen
Subject: Re: Raytracing page[s]
Date: 19 Jul 2017 15:04:57
Message: <596f7519$1@news.povray.org>
On 7/19/2017 1:01 PM, Bald Eagle wrote:
> "Kenneth" <kdw### [at] gmailcom> wrote:
>
>> Thanks for posting this link. I need as many sources as I can find, to help me
>> further understand how a matrix works, and its many uses.
>
> Well, I'm sure there are many different types of matrix - and the graphics /
> camera / projection matrix is a special application.
>
>> For example, the real magic of Rune's ILLUSION.INC include file lies in
>> his use of a matrix, with amazing results. I'm still trying to understand what
>> he did!)
>
> Just by taking a quick look at the code, (I've never used it, and the sample
> file output makes no sense to me) I'd have to say that it just takes a "flat"
> image and skews it - stretches it - so that it fits / lines up correctly with
> the field of view from the camera position - a perspective correction.
>

I've used it and would say it more translates the rays than skews them.


> This is also something I need to look into, and have only briefly played with it
> to correct some perspective distortion of photographed flat surfaces.
>
> I'm sure it could be harnessed to do some basic photogrammetry, if I ever live
> that long, have enough round tuits, and triple my caffeine intake.  ;)
>
> Glad you can use the link - it looked like a good one.   Lohmueller of course
> has some examples on his page[s] as well, and many examples are available via
> the insert menu.
>
>

You might be interested in Dr. John's FieldCam macro.

>
> Greetings, all. I have a macro that simulates a shifted lens which may
> help you. I will repost it in p.b.s-f. as FieldCam.zip. In the zip are
> three folders; one for Mac users, one for Unix users and one for M$
> users. Hope it helps

http://news.povray.org/povray.binaries.scene-files/thread/%3C48400449$1@news.povray.org%3E/?ttop=328092&toff=50



-- 

Regards
     Stephen


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