comp.lang.idl-pvwave archive: archive » Re: How to detect ellipse intersection

Home » Public Forums » archive » Re: How to detect ellipse intersection

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: How to detect ellipse intersection [message #70854 is a reply to message #70853]

Fri, 07 May 2010 07:24

pgrigis
Messages: 436
Registered: September 2007

Senior Member

On May 7, 10:10 am, Paolo <pgri...@gmail.com> wrote:
> On May 7, 4:53 am, oupin <hhb1...@gmail.com> wrote:
>
>> I have hundreds and thousands ellipse, which includes center
>> coordinates and major/minor axis and azimuth of major axis. Now I want
>> to detect which pairs ellipse intersect, how can I realize this
>> program using IDL?
>
> first, select pairs that could possible have an intersection
> (i.e. distance between centers less or equal the larger of the
> two semimajor axes) - no point in bothering with far apart pairs.
^^^^^^^^^^^^^^^^^^^^
times 2 of course :)

>
> second, find the intersection points. I guess they are given by
> a 4th degree equation (since each ellipse is 2nd degree, and there
> can obviously be from 0 to 4 intersections), so you should be
> able to solve it exactly... but some smart geometer may have a better
> approach :)
>
> Ciao,
> Paolo

Report message to a moderator

[Message index]

		Re: How to detect ellipse intersection By: ben.bighair on Sat, 08 May 2010 11:58
		Re: How to detect ellipse intersection By: penteado on Fri, 07 May 2010 07:25
		Re: How to detect ellipse intersection By: pgrigis on Fri, 07 May 2010 07:24
		Re: How to detect ellipse intersection By: pgrigis on Fri, 07 May 2010 07:10

Previous Topic:	match_2d
Next Topic:	Why postscript colors are same as screen?

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Sat Oct 11 09:27:53 PDT 2025

Total time taken to generate the page: 0.95900 seconds