Документ взят из кэша поисковой машины. Адрес
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.