Sure, pixels were probably not the best word to use. I have 15
points(elements) per scan line per "variable" directly from an aircraft
instrument. So I might have a 15 element array of brightness
temperatures, a 15 element array of latitudes corresponding to those
points in the BT array, and another 15 element array of longitudes
corresponding to those points in the BT array. So the first element in
the brightness temperature(BT[0]) array represents an area of the earth
located at lon[0],lat[0] (I'm actually not sure if its the center of the
area or the corner, but at the moment that doesn't matter).
Does that make sense?
-Dave
On 7/21/12 9:46 AM, Chaitanya kumar CH wrote:
Dave,
You said that you have lat/lon values for each pixel. Can you explain?
On Fri, Jul 20, 2012 at 8:44 PM, David Hoese <dho...@gmail.com
<mailto:dho...@gmail.com>> wrote:
I'm attempting to put aircraft scan data into geotiffs (1-3
scanlines each) and then use gdal_merge.py to combine them into
one large geotiff that has the entire aircraft's path. The scan
lines are 15 pixels wide and taken every 10 seconds, the geotiffs
are wgs84 lat/lon, and I have lat/lon values for each pixel. To
handle the case when the aircraft isn't flying straight north I
think I have to use the 2 rotation parameters in the affine
geotransform, is that right? I don't have any test cases, but I
think if I don't use rotation anything that reads the geotiff will
think that the image is square(aligned) in lat/lon space.
Whether or not I need to use this, can someone explain to me how
to use the rotation coefficients? What are the actual values of
the coefficients supposed to be? I couldn't find a good example
and I couldn't get any basic situations to make sense, like a 2x3
array turned 45 degrees. I used these equations:
Xgeo = GT(0) + Xpixel*GT(1) + Yline*GT(2)
Ygeo = GT(3) + Xpixel*GT(4) + Yline*GT(5)
And lastly, does gdal_merge.py handle rotation? I checked the
source and it doesn't ever seem to use elements 2 and 4 in its
calculations.
Thanks for any help.
-Dave
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Best regards,
Chaitanya kumar CH.
+91-9494447584
17.2416N 80.1426E
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