RE: MI MapBasic : Distance point to line

[Warren Vick, Europa Technologies Ltd.]

Hello V�ronique,

May I add to Bill's reply that a truly accurate implementation of
point-object distance is not very efficient to implement in MB as it
involves iteration through nodes. This is the reason why many utilities will
compromise accuracy by not calculating the true perpendicular distance.
Also, ensure that very long "straight" lines have a suitable number of
coincident nodes. This will reduce errors induced by the geometric straight
line vs. great circle path discrepancy.

Regards,
Warren Vick
Europa Technologies Ltd, U.K.
http://www.europa-tech.com

> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Bill Thoen
> Sent: Friday, December 17, 1999 6:57 PM
> To: V. VESTRI
> Cc: '[EMAIL PROTECTED]'
> Subject: Re: MI MapBasic : Distance point to line
>
>
> The shortest distance between a point and a line is the length of
> a line originating at the point and intersecting the line
> perpendicularly (not necessaerily the midpoint). You also have to
> test the line's endpoints if a perpendicular intersection cannot
> be drawn from the point to a line segment.
>
> - Bill Thoen
>
>
> "V. VESTRI" wrote:
> >
> > Hello,
> >
> > Can you tell me how to calculate the minimum distance between one point
> > and few lines or polylines with MapBasic ?
> >
> > It's the last point of my developpement and i don't have idea how i can
> > do that.
> > My MapBasic application is simple :
> > - it create circle, using coordinates in a table
> > - user define the radius
> > - it select all line or polyline in the circle
> > - it calculate the minimum distance between the circle centroid and this
> > line or polyline
> >
> > I'm sorry for this very bad english ...
> >
> > Thanks a lot,
> >
> > V�ronique VESTRI
> > Ing�nieur S.I.G.
> > [EMAIL PROTECTED]
> >
> > ASCOPARG
> > Surveillance de la qualit� de l'air
> > dans la r�gion grenobloise
> > FRANCE
> >
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