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Improve compress ratio when saving GeoTIFFs #2002

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joa-quim merged 1 commit into from
May 12, 2026
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Improve compress ratio when saving GeoTIFFs #2002

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8 changes: 4 additions & 4 deletions ext/GMTDGTLidarExt/GMTDGTLidarExt.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -400,7 +400,7 @@ module GMTDGTLidarExt
ext_lc = use_mem ? ".tiff" : lowercase(splitext(outfile)[2])
fmt_opts = ext_lc == ".nc" ? ["-of", "netCDF", "-co", "FORMAT=NC4", "-co", "COMPRESS=DEFLATE", "-co", "ZLEVEL=4"] :
use_mem ? ["-of", "GTiff"] :
["-of", "GTiff", "-co", "COMPRESS=DEFLATE", "-co", "PREDICTOR=2", "-co", "TILED=YES",
["-of", "GTiff", "-co", "COMPRESS=ZSTD", "-co", "PREDICTOR=3", "-co", "TILED=YES",
"-co", "BLOCKXSIZE=512", "-co", "BLOCKYSIZE=512"]

# Resolve output CRS: "geog" → EPSG:4326, bare digits → EPSG:<n>, anything else → pass directly
Expand Down Expand Up @@ -857,11 +857,11 @@ module GMTDGTLidarExt
end

# Rewrite a GeoTIFF in-place with DEFLATE compression + tiling.
# PREDICTOR=2 (horizontal differencing) improves ratio for integer/float data alike.
# PREDICTOR=3 (horizontal differencing) improves ratio for integer/float data alike.
function _compress_tiff(file_path::String)
tmp = file_path * ".tmp.tiff"
try
GMT.gdaltranslate(file_path, ["-co", "COMPRESS=DEFLATE", "-co", "PREDICTOR=2",
GMT.gdaltranslate(file_path, ["-co", "COMPRESS=DEFLATE", "-co", "PREDICTOR=3",
"-co", "TILED=YES", "-co", "BLOCKXSIZE=512", "-co", "BLOCKYSIZE=512"]; save=tmp)
mv(tmp, file_path; force=true)
catch e
Expand Down Expand Up @@ -910,7 +910,7 @@ module GMTDGTLidarExt
# Use GDAL /vsicurl/ to translate remote TIFF in one step (no download-then-recompress).
if extension == ".tiff" && compress == "tif"
GMT.gdaltranslate("/vsicurl/" * final_url,
["-co", "COMPRESS=DEFLATE", "-co", "PREDICTOR=2", "-co", "TILED=YES",
["-co", "COMPRESS=ZSTD", "-co", "PREDICTOR=3", "-co", "TILED=YES",
"-co", "BLOCKXSIZE=512", "-co", "BLOCKYSIZE=512"]; save=file_path)
elseif extension == ".tiff" && compress == "nc"
GMT.gdaltranslate("/vsicurl/" * final_url,
Expand Down
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