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Understanding IDLanROI [message #72853]

Fri, 08 October 2010 14:13

KRDean
Messages: 69
Registered: July 2006

Member

I am attempting to use IDLanROI to determine if Shapefiles overlap
another Shapefile.

Sometimes it works, sometimes it doesn't. Especially, if the polygon
lies within the interior.

I put together a test program that retrieves the States and uses
IDLanROI to determine if it lies within the US.

Why does Colorado not considered to be in the United States, among
some other interior States?

Is IDLanROI not the IDL routine to use to perform this check?

Kelly Dean
Milliken, CO

;+
;
;
;
;----------------------------------------------------------- -----------
PRO ITT_PolyOverlap

states_path = FILEPATH('states.shp',SUBDIR=['resource', 'maps',
'shape' ])
country_path = FILEPATH('country.shp',SUBDIR=['resource', 'maps',
'shape' ])

PRINT, states_path
PRINT, country_path

oSHP = OBJ_NEW('IDLffShape', country_path )
ent1 = oSHP -> GetEntity( 34, /ATTRIBUTES ) ; USA
OBJ_DESTROY, oSHP

PRINT, ' -- Working with country : ', (*ent1.attributes).attribute_4

oSHP = OBJ_NEW('IDLffShape', states_path )
oSHP -> GetProperty, N_ENTITIES = num_ent
FOR staten = 0, num_ent DO BEGIN

oSHP = OBJ_NEW('IDLffShape', states_path )
ent0 = oSHP -> GetEntity( staten, /ATTRIBUTES )

oROI = OBJ_NEW('IDLanROI', (*ent1.vertices) )
pttest = oROI -> ContainsPoints( (*ent0.vertices) )
OBJ_DESTROY, oROI

overlap = WHERE( ptTest GT 0, count )

IF ( count GT 0 ) THEN BEGIN
PRINT, ' === ' , (*ent0.attributes).attribute_1, ' inside ',
(*ent1.attributes).attribute_4, ' === ', count
ENDIF ELSE BEGIN
PRINT, ' <<< ' , (*ent0.attributes).attribute_1, ' outside ',
(*ent1.attributes).attribute_4, ' >>> ', count
ENDELSE

ENDFOR

OBJ_DESTROY, oSHP

END

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[Message index]

		Understanding IDLanROI By: KRDean on Fri, 08 October 2010 14:13
		Re: Understanding IDLanROI By: KRDean on Tue, 19 October 2010 08:02
		Re: Understanding IDLanROI By: David Fanning on Tue, 19 October 2010 10:38
		Re: Understanding IDLanROI By: guillermo.castilla.ca on Wed, 20 October 2010 10:01
		Re: Understanding IDLanROI By: KRDean on Fri, 22 October 2010 07:16
		Re: Understanding IDLanROI By: Matt[2] on Mon, 25 October 2010 09:17
		Re: Understanding IDLanROI By: guillermo.castilla.ca on Wed, 27 October 2010 08:44
		Re: Understanding IDLanROI By: guillermo.castilla.ca on Mon, 01 November 2010 06:23
		Re: Understanding IDLanROI By: guillermo.castilla.ca on Mon, 01 November 2010 06:24
		Re: Understanding IDLanROI By: David Fanning on Tue, 19 October 2010 14:02
		Re: Understanding IDLanROI By: KRDean on Tue, 19 October 2010 13:19

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