| Re: Get pixel info from an geotiff ROI (lat long) [message #57591 is a reply to message #57590] |
Sun, 16 December 2007 17:10   |
aleks.franca@gmail.co
Messages: 33
Registered: March 2007
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Member |
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> POLYFILLV will return all the pixel indices inside your
> polygon. But I would really think about putting these
> ROIs into IDLanROI objects. That way you get methods that
> do just about everything you can think of to do with an
> ROI.
>
> Cheers,
>
> David
Thank you David. Your hint was of good help, but I still have some
problems. I'm using POLLYFILLV because I still have problems with
objects, but I'll get over it soon.
The input is a txt file with the coordinates of a Region in lat long.
I take that and interpret each coordinate in a pixel value:
vetGridX = intarr(n_elements(vetLonX))
vetGridY = intarr(n_elements(vetLatY))
for i=0, n_elements(vetGridX)-1 do $
begin
vetGridX[i] = fix((vetLonX[i] - LongMin) / pixelSize_X)
vetGridY[i] = fix((vetLatY[i] - LatMin) / pixelSize_Y)
endfor
vetGridY = (2791-vetGridY) ;2791 is the ysize of the image
;I have then 2 vectors if integer
VETGRIDX INT = Array[554]
VETGRIDY INT = Array[554]
;After that I make them become vectors of a single string.
vetGridX = strtrim(vetGridX, 2)
vetGridY = strtrim(vetGridY, 2)
vetGridX = STRJOIN(vetGridX, ',')
vetGridY = STRJOIN(vetGridY, ',')
;This is an example of the first and last points of the string.
;Note that some points are repeated.
VETGRIDX STRING = 769,769,770,770,770 ...
771,771,770,770,770,770,770,770,770,770
VETGRIDY STRING = 1100,1100,1100,1100,1100 ...
1101,1101,1101,1101,1101,1101,1101,1100,1100,1100
;I use the function like this:
P = img[polyfillv([VETGRIDX], [VETGRIDY], 4453, 2791)]
And this is the result
% POLYFILLV: Not enough valid and unique points specified.
I've thougth that the first and the last point cannot repeat, so I've
tried that and the function works just once and never happened again.
That's very crazy.
Would someone help me on that?
Thank you!
Aleksander
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