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Re: Finding a points inside polygon [message #32646 is a reply to message #32630]

Thu, 24 October 2002 14:06

Pavel A. Romashkin
Messages: 531
Registered: November 2000

Senior Member

I plotted the polygon and the point as you specify. It looks to me that
the point does lie outside the polygon, some 0.0001x and 0.001y to the
right and below the border, to be exact. Check the coordinates, make
sure the floating point precision does not play a joke on you.
David's INSIDE returns zero also.
Make sure your polygon is closed:
vx = [vx, [vx[0]]
vy = [vy, vy[0]]
IDL> print, inside(x, y, vx, vy)
0
So I suspect that there is nothing wrong with the ROI object in this case.
Good luck,
Pavel

Gunho Sohn wrote:
>
> polygon vertices (vx,vy):
> vx=[35.859278 55.591451 155.00000 155.00000]
> vy=[0.00000000 0.00000000 19.279154 23.105984]
>
> point (x,y):
> x=122.87897 y=13.049367
>
> When I simply coded this as follows, it printes as 0 which means this point
> is located outside of polygon. But, it is not!
> o_poly=obj_new('IDLanROI', vx,vy)
> print, o_poly->ContainsPoints(x,y)
>
> I compared this using fanning's inside.pro, as I expected 'inside.pro' said
> this point is in the polygon.
>
> Do I something wrong using IDLanROI object?
>
> I hope to hear anything from you soon.
>
> Many thanks,
>
> Gunho

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[Message index]

		Re: Finding a points inside polygon By: James Kuyper on Thu, 24 October 2002 08:17
		Re: Finding a points inside polygon By: James Kuyper on Thu, 24 October 2002 07:47
		Re: Finding a points inside polygon By: Pavel A. Romashkin on Thu, 24 October 2002 14:06

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