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<p>Hi,</p>
<p>I was reading through <a href="https://kokoalberti.com/articles/geotiff-compression-optimization-guide/">https://kokoalberti.com/articles/geotiff-compression-optimization-guide/</a> (very interesting article) and I am wondering about how to interpret read-speed vs compression. With this article I learned about the relatively new zstd compression and LERC, which is esp. interesting for LIDAR/DTM data in float32.</p>
<p>In general, when you compress more, the read-speed decreases. So an uncompressed file would read very fast. But isn't this gain in read speed at the expense that you have to read a substantially higher amount of data when you use uncompressed or low-compressed data?</p>
<p>E.g. in the table <a href="https://kokoalberti.com/articles/geotiff-compression-optimization-guide/read_results.png">https://kokoalberti.com/articles/geotiff-compression-optimization-guide/read_results.png</a></p>
<p>when you read a float32 dtm with zstd compression, predictor 3 and zstd_level 9, it shows a substantially lower read rate compared to predictor 1 (not optimized for float32). But given that predictor 3 compresses substantially better than predictor 1 for float32, isn't the read-rate "overall" just as good with predictor 3?</p>
<p>Formulating my question different: isn't the read-rate at <a href="https://kokoalberti.com/articles/geotiff-compression-optimization-guide/read_results.png">https://kokoalberti.com/articles/geotiff-compression-optimization-guide/read_results.png</a> a bit distorted by the fact that higher-compression means that you also have to read substantially smaller file sizes? Shouldn't this table with the read-rate be kind of "normalized" with the file sizes it has to read for exactly the same data?</p>
<p>Currently, it just lists MB/CPU-sec.</p>
<p>Thanks for the discussion,</p>
<p>Andreas</p>
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