POV-Ray : Newsgroups : povray.programming : About the Intersection points again Server Time
23 Dec 2024 06:39:59 EST (-0500)
  About the Intersection points again (Message 1 to 6 of 6)  
From: Wu Yang
Subject: About the Intersection points again
Date: 17 Nov 2002 19:21:34
Message: <3dd8328e$1@news.povray.org>
Hi, all
  I have got the distance between the camera and the nearest intersection
point. And I made the object move by adding "clock". What I want is the
distance change between two pictures, the distance is to the same point of
the object. Because the object I observe moved, so it is so difficult to
track it. What should I do? Thanks

Best Regards
Wu Yang


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From: Christopher James Huff
Subject: Re: About the Intersection points again
Date: 17 Nov 2002 20:49:59
Message: <chrishuff-650D25.20485717112002@netplex.aussie.org>
In article <3dd8328e$1@news.povray.org>,
 "Wu Yang" <wya### [at] cswrightedu> wrote:

>   I have got the distance between the camera and the nearest intersection
> point. And I made the object move by adding "clock". What I want is the
> distance change between two pictures, the distance is to the same point of
> the object. Because the object I observe moved, so it is so difficult to
> track it. What should I do? Thanks

The first intersection points just won't be the same. Look at it this 
way: the points make up a sheet stretched over the scene from the point 
of view of the camera. As the object moves, the sheet "ripples", but 
doesn't shift around. You get one set of points on the object at one 
position, and an entirely different set of points on the object at a 
different position. If you want points on the object that move, this 
data is useless.
If you just want the change in distance to the camera, one possibility 
would be to compute the change in average or minimum distance. It would 
really help if you just said what you wanted...

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/


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From: Wu Yang
Subject: Re: About the Intersection points again
Date: 18 Nov 2002 02:14:00
Message: <3dd89338@news.povray.org>
Thank you for your reply.

>It would really help if you just said what you wanted...

  I called the distance between the camera and a intersection point the
RANGE of that point, and what I want now is the Range Rate of that point
when the object moves. Range and Range Rate are two important parameters for
Target Tracking. I am now trying to generate date (Range, Range Rate) from
this program for a target tracking test.


>If you just want the change in distance to the camera, one possibility
would be to compute the change in average or >minimum distance.

What I need is the Range Rate of every intersection point not just the
average and minimum Range's.


>The first intersection points just won't be the same.

Yes, I agree. This is exactly the difficulty to get the Range Rate.

Best Regards
Wu Yang


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From: ABX
Subject: Re: About the Intersection points again
Date: 18 Nov 2002 02:14:11
Message: <ek4htus749ipavtvu6i4aj7k8drlr5hmeq@4ax.com>
On Sun, 17 Nov 2002 19:22:24 -0500, "Wu Yang" <wya### [at] cswrightedu> wrote:
> Because the object I observe moved, so it is so difficult to
> track it. What should I do?

http://mathworld.wolfram.com/Distance.html

ABX


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From: ABX
Subject: Re: About the Intersection points again
Date: 18 Nov 2002 02:55:59
Message: <e07htucrt2fuh7a45f7braabavdk287mbf@4ax.com>
On Mon, 18 Nov 2002 02:14:50 -0500, "Wu Yang" <wya### [at] cswrightedu> wrote:
> What I need is the Range Rate of every intersection point not just the
> average and minimum Range's.

Then instead of creating object and patching POV just open editor and create
objects as set of points on their surfaces and calculate changes for each
point separately.

ABX


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From: Christopher James Huff
Subject: Re: About the Intersection points again
Date: 18 Nov 2002 12:28:19
Message: <chrishuff-2FA841.12271818112002@netplex.aussie.org>
In article <3dd89338@news.povray.org>, "Wu Yang" <wya### [at] cswrightedu> 
wrote:

> >It would really help if you just said what you wanted...
> 
>   I called the distance between the camera and a intersection point the
> RANGE of that point, and what I want now is the Range Rate of that point
> when the object moves. Range and Range Rate are two important parameters for
> Target Tracking. I am now trying to generate date (Range, Range Rate) from
> this program for a target tracking test.

If you just want a point on the object that moves around with the 
object, there is no need for patching POV. Just define a point that is 
on the object, or at the center of it, or whatever you want to define it 
as, and then apply the same transformations to that point and the 
object. If you had just said this at the beginning, your question could 
have been answered then, there would have been no need for all these 
messages and threads.


> >If you just want the change in distance to the camera, one possibility
> would be to compute the change in average or >minimum distance.
> 
> What I need is the Range Rate of every intersection point not just the
> average and minimum Range's.

Read what I said again...the *change* in average or minimum distance. 
You must define what you want "range" to be, it could be average or 
minimum distance, distance to a constant point on the object, or 
something else. The change in this value would be the rate of distance 
(or "range") change in units per frame. However, even if you decided to 
do it this way, patching POV is not necessary, it could be done in the 
existing scene language with the trace() function.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/


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