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Lossless compression information for LERC #89
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fix: lerc is not lossy unless max_z_error is > 0
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I don't think this explanation is the full story, but generally agree this needs an update. The issue I have with the fix is that the GDAL/ArcGIS parameter is called MAX_Z_ERROR/Max-error not Precision. Which to me is different since precision is to what decimal place is the data stored, and max error, is how far is the value allowed to change from what's currently stored. Net effect is the same but explaining the number is different. Precision would be a number like 3, but the equivalent max error would be .001? https://kokoalberti.com/articles/geotiff-compression-optimization-guide/ cc: @vincentsarago |
@wildintellect I completely agree there is a jumbling of terms error vs precision, I originally had it as MAX_Z_ERROR but I thought that may be too GDAL specific and reworded it to precision as it was used earlier in the paragraph. How about something like :
Or going back to MaxZError as its referenced on https://github.com/Esri/lerc#when-to-use
I was also trying not to completely change the flow of this paragraph being as it is my first pull request. This section could be changed further, LERC is quite good (fast compression/decompression & good output size) for most lossless applications I have tried, uint8 (RGBA), uint16(RGBi), float32(DEM/DSM). It also has a nice wasm interface for accessing raw pixel values in a browser. |
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I think we should note that this compression algorithm can be used for non-floating point data as well and link to the source
noticed small changes to be made
Update Zarr visualization link
Feedback during PR Co-authored-by: Aimee Barciauskas <[email protected]>
What Changed
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