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| Re: How to spatial subset files by ENVI vector file (EVF) or other shapefile ? [message #57722 is a reply to message #57587] |
Mon, 17 December 2007 08:52  |
Jean H.
Messages: 472
Registered: July 2006
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Senior Member |
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Lucia wrote:
> I can spatial subset files by EVF in ENVI, but I need to do it by IDL.
Hi,
You can start with this..
Jean.
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;open the evf file
vectID = ENVI_EVF_OPEN(VectorToOpen)
;get the numbers of records (polygons) in the vector file
ENVI_EVF_INFO, vectID, num_recs = numRecs
;Open the image. We will get the pixel locations of the polygons out of it.
envi_open_file,ImageFilename,r_fid=fid
;get the X and Y dimensions of the image
ENVI_FILE_QUERY, fid, nl=nl, ns=ns
; Loop through each record
for record=0,numRecs-1 do begin ;
;get the coord of each nodes of the current polygon; Coords are
projected.
pts_polygon_proj = envi_evf_read_record(vectID, record)
;convert the projected coordinates of the nodes to a line/column
coordinate
envi_convert_file_coordinates,fid,pts_X_polygon_pixel,pts_Y_ polygon_pixel,pts_polygon_proj[0,*],pts_polygon_proj[1,*]
;Get the 1D cell indices of the cells lying under the current polygon.
polygonIndices =
polyfillv(round(pts_X_polygon_pixel),round(pts_Y_polygon_pix el), ns, nl)
endfor
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