The encoding of digital information in order to store it using fewer bits.

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57 views

How to configure Apache for topojson gzip files

Building an online interactive map with leaflet and some heavy layers with my spatial data in topojson format. I have been reading about gzip but I am still uncertain how to configure it. Do I need ...
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50 views

Reading Jp2 compression level using ArcPy?

Is the compression quality level used to create a JPEG2000 image stored somewhere inside the file, and how to read it? I would like to know if my images where generated using a lossless compression ...
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1k views

Why does compressed & zipped/unzipped file geodatabase give Open Failed Error opening feature class Cannot access secured data?

In ArcGIS 10.2 for Desktop, a colleague compressed a file geodatabase and then zipped it and sent it to me via email. I unzipped it and was unable to add any of the feature classes into my map ...
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21 views

Vanilla PHP and GeoTIFF: How to know byte address and byte length of a “strip” in an LZW-compressed GeoTiff?

I have a situation where I need to read cell values from a GeoTiff using vanilla PHP, and while I've been successful reading values from an uncompressed TIF (~800MB), I'm having difficulty reading ...
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108 views

Classify trajectory compression algorithm

I'm tryng to classify each compression algorithm based upon their features, i've thinked: Compression algorithm Lossless algorithm Batched algorithm Rinex Lossy algorithm Batched algorithm ...
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87 views

TileStache PNG Optimization

A Tilestache config file has a "png options" object that passes its config straight through to the Python Imaging Library (PIL). Setting optimize: true does some kind of optimization as the file is ...
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293 views

Compression Algorithms output files larger than the originals. Why?

I'm currently attempting to write a script that will compress a few hundred .tif files. I've tried two approaches, first I wrote a script in Python using CopyRaster_management() function and the ...
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39 views

Has anyone success using subset an image such as NAIP?

Has anyone any luck subsetting a small part out from NAIP? I'd like to hear your feedback on pros or cons on how to subset an image from NAIP despite they are in mrsid and their uncompressed file size ...
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156 views

Raster format similar to ECW

I need an alternative to the ECW format that we currently have for a new series of Ordnance Survey maps. The ECW format looks clearer and less pixelated than the new maps in Tif format (in QGIS). ...