Coyote Graphics Map Projection Routines

Date: Fri Nov 29 13:44:27 2013

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top cgCliptoMap

Map Utilities

result = cgCliptoMap(imageIn, boundary [, LATLONBOX=fltarr], MAP=object [, OUTBOUNDARY=fltarr] [, OUTMAP=object] [, OUTPOSITION=intarr])

Allows an image or geoTiff file to be clipped or subset to a map projected boundary.

Return value

The clipped or subsetted image is returned.


imageIn in required type=varies

Either a 2D or true-color image (in which, in both cases, a map coordinate object must be provided with the MAP keyword) or the name of the GeoTiff file from which an image and a map coordinate object can be obtained.

boundary in required type=fltarr

A four-element array containing the map boundary to which the image should be clipped.


LATLONBOX out optional type=fltarr

A four-element array representing the boundary of the output image in the Google Map preferred form of [north, south, east, west] in decimal degrees.

MAP in required type=object

A map coordinate object (cgMap) that maps or georeferences the input image.

OUTBOUNDARY out optional type=fltarr

A four-element array containing the final map boundary of the clipped image. The boundary will be in XY coordinates (projected meters).

OUTMAP out optional type=object

An output map coordinate object (cgMap) that describes the output image.

OUTPOSITION out optional type=intarr

A four-element array containing the pixel locations of the output image in the input image pixel coordinate system: [x0,y0,x1,y1]. In other words, these are the values used to subset the input image.

Author information



David W. Fanning 1645 Sheely Drive Fort Collins, CO 80526 USA Phone: 970-221-0438 E-mail: Coyote's Guide to IDL Programming:


Copyright (c) 2012, Fanning Software Consulting, Inc.


Change History:

Written, 16 August 2012. DWF. If the absolute value of the maximum of the boundary is LE 360, assume you need to convert from lat/lon space to projected meter space. 23 Aug 2012. DWF. Added MAPOUT and LATLONBOX keywords. 1 Nov 2012. DWF. Added OUTPOSITION keywords. 29 Nov 2012. DWF. I have reason to believe the way I was creating the location vectors and and image subset in this program was causing me to be 1 pixel off in creating the image subset. The algorithm has been tweaked to correct this. 12 Dec 2012. DWF.

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Modification date: Thu May 16 08:15:24 2013
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