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Re: Map to data coordinate conversion [message #83923]

Thu, 18 April 2013 08:27

PMan
Messages: 61
Registered: January 2011

Member

On Thursday, April 18, 2013 11:12:16 AM UTC-4, Chris Torrence wrote:
> On Thursday, April 18, 2013 8:19:48 AM UTC-6, Paul Mallas wrote:
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>> Hello all,
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>> I am looking to convert, given a geotff image with map info, the lat/lon data to a pixel location in an image.
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>> What I want to do seems pretty easy, but I am having a hard time coding it in IDL for some reason. I must be missing something.
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>> Using the ENVI() API, this was straight forward:
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>> oEnvi = envi(/headless)
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>> eMask = oEnvi->openRaster(file)
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>> fid = ENVIRasterToFID(eMask)
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>> envi_convert_file_coordinates, fid, xf, yf, lon, lat
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>> with lon, lat being my predefined input and xf, yf being my desired output.
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>> The analogous way to do this in IDL is (I think):
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>> img = image(file, /buffer)
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>> xy = img->convertcoord(lon, lat, /to_data)
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>> however the image() function won't read the geotiff properly (but ENVI() accepts it just fine). Perhaps my geotiff tag is not properly formed or something. Ideas on another way?
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> Hi Paul,
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> I think you want to use the MapForward method. Something like this:
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> i = image(FILEPATH('boulder.tif',SUBDIR=['examples','data']))
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> print, i.mapforward(-105,40)
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> The ConvertCoord is just for converting between screen/normalized/data coordinates, and not between lat/lon and data.
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> Hope this helps.
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> -Chris
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> ExelisVIS

Great - that's what I am thinking of.

I am encountering a problem with image() though - my geotiff won't load with correctly. I get this error:
IMAGE: Unable to invoke method on NULL object reference: <OBJREF (<NullObject>)>.

This same image works just fine with the ENVI API - perhaps there is some deficiency in my geotiff values.

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[Message index]

		Re: Map to data coordinate conversion By: PMan on Thu, 18 April 2013 08:27
		Re: Map to data coordinate conversion By: Fabzi on Thu, 18 April 2013 08:20
		Re: Map to data coordinate conversion By: PMan on Thu, 18 April 2013 08:15
		Re: Map to data coordinate conversion By: chris_torrence@NOSPAM on Thu, 18 April 2013 08:12
		Re: Map to data coordinate conversion By: David Fanning on Thu, 18 April 2013 07:40
		Re: Map to data coordinate conversion By: David Fanning on Mon, 22 April 2013 05:20
		Re: Map to data coordinate conversion By: chris_torrence@NOSPAM on Fri, 19 April 2013 16:06

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