From mcneills@landcare.cri.nz Fri Feb 3 13:04:56 1995 Path: solitaire.cv.nrao.edu!hearst.acc.Virginia.EDU!portal.gmu.edu!europa.eng.gtefsd.com!news.mathworks.com!newshost.marcam.com!hookup!uwm.edu!math.ohio-state.edu!howland.reston.ans.net!news.starnet.net!wupost!waikato!comp.vuw.ac.nz!zephyr.grace.cri.nz!cyclone1.grace.cri.nz!mcneills From: mcneills@landcare.cri.nz (Stephen McNeill) Newsgroups: sci.geo.satellite-nav Subject: Re: Help:: opening a SPOT image w/ Photoshop on Mac Date: Sat, 4 Feb 1995 00:32:01 LOCAL Organization: Landcare Research New Zealand Ltd Lines: 68 Message-ID: References: <1995Jan31.135946.1@carleton.edu> NNTP-Posting-Host: cyclone1.grace.cri.nz X-Newsreader: Trumpet for Windows [Version 1.0 Rev B final beta #4] In article <1995Jan31.135946.1@carleton.edu> fehlerd@carleton.edu (Farmer Dan) writes: >I need information on how to open a SPOT satalite image using Adobe Photoshop >3.0 on a Mac Quadra using system 7. Or else using Multispec, same system. >The image size is about 3000X4000 with 3 interleaved bands, about 50Megs total >size. the Mac has 24Meg RAM, but we don't get a disk/full error message. All >we get are diagonal lines across where the image should be. The image comes >with several files, but we have only been working with the image.dat file. >Do I need to convert these images? Should I be using a different application? You don't specify how you have loaded these images exactly, but from the above description, I presume you have a SPOT CD-ROM, correct ? Since the image is 3000 by 4000, you are probably dealing with a Multispectral level 1B image. Ok so far ? If so, then you are probably dealing with a CEOS format disk (Committee on Earth Observing Systems). The format was formally known as the LGSOWG family format (pronounced "log-swog"). It seems a little unusual that the image is called "image.dat", since if it is a SPOT CD-ROM then the imagery file should have a name like "imag_01.dat" for the first image, "image_02.dat" for the second image on the disk etc. This is the convention for CD-ROMs from SPOT Image at least, but perhaps you are dealing with a country variant. The other little files are quite useful, since they give you volume, scene, and processing information. You should really get a copy of the CEOS format, or the variant that was used to write your disk. If you want a quick-fix to your problem of reading the data, the solution would be to read from the imagery file, but specifying the total record size for each imagery line, and if possible skipping the prefix data at the start of the line. The records will be either 3960, 5400 or 8640 bytes long (from memory), so if you have "about 4000 pixels in a line" then you are probably dealing with the 5400 byte case (the most common). Find out exactly how many ! Skip 32 bytes at the start of each line. The first four bytes in each line will form a binary representation of the image record number. The numbers should ascend, but very early SPOT data did sometimes descend. You can find the length of the record in binary in bytes 9 to 12. But this is only a quick-fix solution. Ideally, you should read the rest of the small files scattered about and use those to work out the structure of the image. It can get messy, but it is a widely used standard for remote sensing data for JERS/SPOT/Landsat and so on, although less so now with Landsat data since EOSAT's Fast Format is so much easier to deal with. Of course, I could be barking up the wrong tree entirely... If you get stuck, let me know. WHAT ! You are at Carleton University ? Do you realise how close that is to your CCRS ? Where do you think this CEOS format was partly invented ? Yes, you can probably guess... Give them a ring... Don't say I sent you, they wouldn't want to speak to me again. Regards Stephen McNeill Image Processing Team Landcare Research New Zealand Ltd Box 38-491 Wellington Mail Centre New Zealand Phone: +64-4-5690183 FAX: +64-4-5690181 Internet: mcneills@landcare.cri.nz