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Satellite image help

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Howdy Everyone,I need some direction in producing satellite images like those that Holger Sandmann was providing until do-it-yourself programs came along. I am using the ERDAS ViewFinder and FGis programs. I've tried several times to get an image like Holger's but with no success.My images are not as large as Holger's (larger lakes and other features) and the LOD13 areas appear as small rectangles rather than the squares as In Holger's images. Here's what I've been doing:I download an image from the glcfapp.umiacs.umd.edu site checking the ETM+ and Require - GeoCover boxes and the Lat/Long tab.The Preview and Download window shows ETM+ and Orth, GeoCover.I extract the compressed file in tif format.Opened the file in TMFViewer Saved as a TIF file Units - degrees Category - Geographic Projection -Lat/Long (WGS84) Resample method - Cubic convolution I didn't change the width and height - might this be where I'm going wrong?I opened FGIS, created a new project and selected a portion of the image with the Export Image Tool and saved it as a BMP.The saved image has the small rectangular LOD13 areas and is not as large as Holger's images.Can anyone tell me where I'm making mistakes?Is there a better program than FGis for processing images?I don't have any of the high-powered programs like Paintshop etc.Any assistance will be very much appreciated.Wil Husted

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Hi Wil.The final bitmap could have rectangular, rather than square LOD13 areas. It should still work fine in Ground2K4. I'm assuming the reprojection tool you used waas TIFViewer? If it has the ability to change width and height, and can make them somehow equal as pixels/arc second, or pixels/degree then do that, and all should look OK.Dick

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Hello Dick,I don't have TIFViewer but will check into it. I used ViewFinder and FGis to get the image I've been playing with. It works but is not as useful as the images that I obtained from Holger. It's not as close-up as Holger's images, like it was taken from a greater distance.Thanks for the suggestions. I'll give them a try.Wil

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Hi Wil.Don't search for TIFViewer... my mistake. You mentioned "Opened the file in TMFViewer", and I assumed that was the wrong filename...and guessed what you meant. Sorry.Holger was probably using GlobalMapper to save his images. That payware program defaults to "square pixels" which probably explains the difference.If Viewfinder allows you to enlarge the outputs dimensions, or pixel-span, that may help solve the problem... maybe Holger can clarify this, as I don't use Viewfinder.Dick

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Howdy,it doesn't make any difference whether the bitmap pixels are square or not; I have various maps and images that show up as rectangles in G2K4. What matters is that the corner coordinates are correct. I usually test a new image by placing a few streams in different parts of the image; the test being whether they fit well with the base mesh. As for the image resolution, Wil, are you using Band 8 of your image set (the one that ends with *_nn80.tif.gz)? It's the only Landsat ETM band that has a 15-m resolution. Also, you definitely need to adjust brightness and contrast of your reprojected image with photo editing software.Cheers, Holger

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Howdy Holger,OK, I feel better all ready. The image I'm messing with has the correct coordinates, it's a section of the larger complete image. I connected the road west of Sylvan Pass in Yellowstone N.P. with rest of the road on eastward to Cody and hit it perfectly the first try. The road agrees well with the topography and the river and road through Shoshone Canyon between Cody and Buffalo Bill Reservoir fit very nicely. No more road and river up and over Rattlesnake Mountain!I did adjust the brightness and contrast as the raw download comes out quite dark. I do need more practice and experience with this angle.My only problem with the image is that it isn't detailed enough to easily place the river in the canyon etc.I'm using the Band 8 image, *_nn80.tif.gz. Thanks a million for the clarifications and information.Wil

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