POV-Ray : Newsgroups : povray.advanced-users : Perspective correction Server Time: 26 Jun 2019 19:53:43 GMT
  Perspective correction (Message 1 to 3 of 3)  
From: Bald Eagle
Subject: Perspective correction
Date: 15 Mar 2017 17:05:01
Message: <web.58c9735a66641a00c437ac910@news.povray.org>
I was wondering if anyone has ever done any perspective correction using POV-Ray
/ SDL.

Something like taking a photograph of a piece of paper at a non-perpendicular
angle, and then applying some sort of matrix transform to the resulting image in
order to get a perspective-corrected result.

I often use photos and diagrams to guide creation of things by CSG, and things
can get to be quite "off".

I was also wondering if some sort of system could be designed to use POV-Ray to
use data points in an image of say, a room, to construct a basic 3D
representation of the room.

I know there are architectural and remodeling apps that can do this, 3D objects
can be seamlessly inserted into legacy photos and video, and IIRC someone had
experimented a while back with using a POV-Ray to identify the location of an
object in the scene using the screen coordinates.

Has anyone thought about any of this?


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From: Thomas de Groot
Subject: Re: Perspective correction
Date: 16 Mar 2017 07:55:36
Message: <58ca44f8$1@news.povray.org>
On 15-3-2017 18:01, Bald Eagle wrote:
> I was wondering if anyone has ever done any perspective correction using POV-Ray
> / SDL.
>
> Something like taking a photograph of a piece of paper at a non-perpendicular
> angle, and then applying some sort of matrix transform to the resulting image in
> order to get a perspective-corrected result.

The much regretted Doctor John had written a macro in 2005 doing just 
that (see attached test file)
>
> I often use photos and diagrams to guide creation of things by CSG, and things
> can get to be quite "off".
>
> I was also wondering if some sort of system could be designed to use POV-Ray to
> use data points in an image of say, a room, to construct a basic 3D
> representation of the room.
>
> I know there are architectural and remodeling apps that can do this, 3D objects
> can be seamlessly inserted into legacy photos and video, and IIRC someone had
> experimented a while back with using a POV-Ray to identify the location of an
> object in the scene using the screen coordinates.

Yes, Norbert Kern wrote a macro in 2006 to find the coordinates of a 
scene location based on the screen coordinates (see attached test file).

>
> Has anyone thought about any of this?
>
>


-- 
Thomas


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From: Bald Eagle
Subject: Re: Perspective correction
Date: 15 May 2017 16:10:00
Message: <web.5919d257c7381058c437ac910@news.povray.org>
I think I may have found something very much in line with what I'm looking for.

Photogrammetry, but also:
https://imcs.dvfu.ru/lib.int/docs/Programming/Graphics/Academic%20Press%20Graphics%20Gems%20Ii%201995.pdf

Skip to page 181 (pg 209 of the actual pdf) to see what I mean.


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