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34

To select compression method you need to use a command like: gdal_translate -co "COMPRESS=method" src_dataset dst_dataset When you use compression biggest trade-off is extra processing time which is required to uncompress the image, and after uncompressing the image would still consume same amount of memory. About information loss there are two basic ...


9

With lzw and deflate compression using -co predictor=2 can help with imagery that is smoothly varying as it compresses the differences from pixel to pixel instead of the absolute values, and these will tend to be small and have more patterns (ref). Predictor is only useful with lzw and deflate compression, the option has no effect with other methods. ...


6

For big rasters GeoTiff offers the possibility to store (pre-)downscaled overviews as extra images to the GeoTiff file. This can be done with gdaladdo (= GDAL ADD Overview). When creating these overviews, you can manually tell gdal to comress them too: gdaladdo --config COMPRESS_OVERVIEW JPEG Speeds up viewing your data without adding too much size. ...


4

I suspect that there are a great number of factors that go into the choice of image format and compression scheme: Image dimensions Bit depth Image complexity (images with large areas of similar colors may actually compress better by a lossless codec than a lossy codec, and some codecs handle complex, detailed areas better than others) Multi-band support ...


3

Try to compress database : http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Compress%20File%20Geodatabase%20Data%20%28Data%20Management%29


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My experience comparing GeoTIFF vs. Earth Resource Mapping's ECW (Enhanced Compressed Wavelet) compression is that ECW is orders of magnitude better when compressing high resolution aerial photos. Another important advantage of wavelet based compression is that, unlike older formats as GeoTIFF, JPEG - not JPEG 2000 -, just a portion of the image can be ...


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Ultimately you'll probably need to experiment with the different options and see what meets your needs. I've been making increased use of JPEG-compressed GeoTIFFs over wavelet-based formats. My results have been pretty good. Using GDAL to do this has yielded compression ratios comparable to wavelet-based formats without too much data loss. The performance ...


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You may even want to consider splitting your geodatabase into two parts, if possible. One for the tax maps, another for photographs. However, if your photos are attributes to your tax layer features, then your you should consider compacting and compressing your file geodatabase, as already mentioned in the comments. A couple of notes about compact vs ...


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As ogr2ogr apparently doesn't work on MAC OS X in this case, I install and test (indicated in GDAL: Arc/Info Binary Coverage): (-> to build the packages -> open terminal, cd to the folder and type make) 1) AVCE00 (Arc/Info (binary) Vector Coverage <-> E00 Library) avcexport' is a command-line executable that takes an Arc/Info binary coverage as ...


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Compression predictors store the difference between neighbouring cell values, rather than the values themselves. If your raster has a continuously-varying value across a field, you may end up with a smaller file size when enabling a predictor. If, however, there are sudden changes in value in your raster, a predictor would probably not help much with the ...


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Well you are always going to lose some quality when you are compressing (unless it is lossless). With that being said, you can still compress it a fair amount and have it not be very noticeable. That is something you can play around with: quality vs. size. I've recently compressed over 1TB of imagery, and JP2 has proven to work well for me. Another option ...


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I'm guessing you're authoring this through Maestro right? I've gotten this error too. Here's how i fixed it: I dont remember why, but Gdal 1.6 didn't do it for me, i had to upgrade to the latest stable version of 1.8 (may work with 1.7, but why use older one?). You can probably compile this yourself or get FWTools, which may have the latest version of ...


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Try and reduce the original tiff to 254dpi >if possible run the exported files through export from Global Mapper via photoshop (fireworks even better) just created and run a batch import/export web optimised .png (don't make a copy, replace the original files) The file size reduction is impressive and therefore speed up your map and tilecache on the ...



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