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What are the acceptable input values for the LERC Precision parameter associated with the OptimizeRasters workflow?

Question asked by matthew.delong on Jun 26, 2017
Latest reply on Jun 26, 2017 by matthew.delong

I have found references that the default is .001 for lossless compression, as well as references that lossy compression can be achieved with 10 - 50 centimeters LERC Precision according to the two white papers concerning the format and more importantly the compression that I have found. I have attempted several variations of this parameter to attempt to discover the relationship between centimeters and the parameter input to the automation but am receiving mixed results. For instance, the values .100, .010, 15, 20, & 25 result in no additional compression outside of the default. A value of 10 results in a file size 50 % or the default and 50 results in about 25% of default. In this case 10 is not enough compression and 50 is the correct file size but with entirely way to much loss to be useful. The other values that provide no further compression are only serving to confuse me further. If relevant the input raster is MrSID with Wavelet MG3 applied at about a 15:1 compression ratio. I appreciate any clarification that can be provided.

 

Thanks

 

Matthew DeLong

Sr GIS Analyst 

Arkansas GIS Office

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