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Re: get LAT/LON from georef image [message #65076 is a reply to message #65075]

Wed, 11 February 2009 11:02

titan
Messages: 59
Registered: March 2006

Member

On 11 Feb, 14:43, "Jean H." <jghas...@DELTHIS.ucalgary.ANDTHIS.ca>
wrote:
> titan wrote:
>> Hello! I have a georef image and I would like to extract the LAT and
>> LON values from it.
>> the dims of my image are not equal, let's say [65,80].
>> I create two vectors to be associated with the x_pixel and y_pixel of
>> the image
>
>> x_pixel=indgen(65)
>> y_pixel=indgen(80)
>
>> I know that there is the envi routine ENVI_CONVERT_FILE_COORDINATES to
>> convert X and Y pixel coordinates into their corresponding X and Ymap
>> coordinates and vice-versa.
>
>> Unfortunately it seems to work only if the lat and lon array are of
>> the same dimension in fact if we consider this example I should write
>
>> envi_convert_file_coordinates, fid, x_pixel, y_pixel, xmap, ymap, /
>> to_map
>
>> in this way I should have the respective vector xmap and ymap of lat
>> and lon
>> but if I write
>
>> help, xmap
>> help, ymap
>
>> I get
>
>> LAT_MAP DOUBLE = Array[65]
>> LON_MAP DOUBLE = Array[65]
>
>> two vector of the same dims (in this case 65) and one of 65 elements
>> and the other with 80 elements
>
>> Could someone tell me where I'm wrong??Are there any methods to
>> overpass this problem??
>> thanks
>
> Titan,
>
> yes, this is normal. x_pixel and y_pixel represent the XY pairs of
> coordinates... I am not too sure of what you are trying to extract
> exactly, but the idea is to create, in pixel index, the coordinates of
> your points of interests.
>
> So, if you want to have the coordinates of the 1st line of pixels, you
> would have:
> X_pixel = indgen(65) ; 0,1,2,3,...
> Y_pixels = intarr(65) ; 0,0,0,0,...
>
> So the pairs are [0,0],[1,0],[2,0] ....
>
> If you want to have the coords of the first column, do
> X_pixel = intarr(85)
> Y_pixels = indgen(85)
>
> And if you want the coord of every pixels,
>
> X_pixels = rebin(indgen(65),65*85) ;0*85 times, 1*85 times etc
> Y_pixels = reform(rebin(indgen(85),85,65),85*65) ;0 to 85, * 65 times
>
> Jean

What I would like to do is to obtain the vector of lat and lon of my
image in order to create an HDF image of the same dims and with the
data of lat and lon associated

thanks

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[Message index]

		Re: get LAT/LON from georef image By: David Fanning on Wed, 11 February 2009 11:08
		Re: get LAT/LON from georef image By: titan on Wed, 11 February 2009 11:02
		Re: get LAT/LON from georef image By: titan on Wed, 11 February 2009 10:58
		Re: get LAT/LON from georef image By: Jean H. on Wed, 11 February 2009 05:43
		Re: get LAT/LON from georef image By: David Fanning on Wed, 11 February 2009 05:43
		Re: get LAT/LON from georef image By: titan on Thu, 12 February 2009 02:03
		Re: get LAT/LON from georef image By: Jean H. on Mon, 16 February 2009 08:13
		Re: get LAT/LON from georef image By: titan on Wed, 18 February 2009 23:57

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