<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">I’m accustomed to GeoTiff files having row-wise sequential layout of image tiles (and I was under the impression that GDAL assumes this for merging range requests)?<div><br></div><div>But I recently noticed a lot of excess GET requests working with SRTM data that passes COG validation scripts:</div><div>> https://opentopography.s3.sdsc.edu/raster/SRTM_GL1/SRTM_GL1_srtm/N59W102.tif</div><div><br></div><div>These files seem to have TileOffsets scattered about (for example here is excerpt from tiffdump: TileOffsets (324) LONG (4) 64<2269213 2409502 3485315 2716342 …)</div><div><br></div><div>I believe this odd layout is causing the many GET requests to access this data, for example:</div><div>CPL_DEBUG=ON gdal_translate -srcwin 0 0 1024 512 /vsicurl/https://opentopography.s3.sdsc.edu/raster/SRTM_GL1/SRTM_GL1_srtm/N59W102.tif test.tif</div><div><br></div><div>Since a key aspect of COGs is efficient network access, shouldn’t this file not be considered a COG? </div><br><div>
<meta charset="UTF-8"><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div>------------------------------<br>Scott Henderson<br>Research Scientist, Earth & Space Sciences<br>Data Science Fellow, eScience Institute </div><div>Johnson Hall 251<br>University of Washington<br>http://scottyhq.github.io</div></div></div>
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