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оригинального документа
: http://xmm.vilspa.esa.es/sas/8.0.0/doc/ommosaic/node10.html
Дата изменения: Wed Oct 22 18:03:35 2008 Дата индексирования: Tue Aug 18 14:55:18 2009 Кодировка: |
Read parameters
Read each input image
If the input images contain a mixture of low and high resolution windows,
convert the high-resolution windows to low resolution ones.
Check that the filters for each file are identical- if not issue a warning.
Set output projection (reference coordinate, pixel size) from the
first input image
Project corners of each input image into output frame to find the
bounds of the output image
Calculate size of output image in pixels from bounds and pixel size
Check the POSCOROK keyword in the header of each input file and,
if the value of this keyword is true then use the reference positions
given by the keywords CRVAL1 and CRVAL2 to calculate the
average values for the corresponding keywords in the header of the
output image.
If at least one input image was astrometry-corrected then
shift the reference pixel of each input image with respect to the
averaged CRVAL1 and CRVAL2 values of the output combined image based
on the individual value of these keywords for the input image.
Create output image
Loop over input images
Normalize each one by its exposure time.
Loop over pixels in output image
Project coordinate of output pixel into frame of input image
Sample input pixel, add sample to output image
Increment each weighting pixel by one if the corresponding input image
pixel is to be coadded to the corresponding mosaiced image pixel.
Increment the corresponding exposure image pixel by the exposure time
for that image.
End loop
End loop
Divide the mosaiced image by the exposure image.
Multiply the image by the exposure time (default 1000 secs).
Write output image
If required, write output exposure map image.