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What a coincidence! I discovered OpenLayers yesterday when looking for a way to display a 1 Terapixel image. I got it up and running in a few hours. Kudos to th
by ghgr 7y ago
What a coincidence! I discovered OpenLayers yesterday when looking for a way to display a 1 Terapixel image. I got it up and running in a few hours. Kudos to the developers!
- degenerate 7y agoAre you serving it as a "static image" or using a different method? https://openlayers.org/en/latest/examples/static-image.html https://openlayers.org/en/latest/examples/static-image.html
- ghgr 7y agoI followed a tiled based approach, as explained here: https://openlayers.org/en/latest/examples/localized-openstreetmap.html https://openlayers.org/en/latest/examples/localized-openstre... Although the image is not a map at all, I tiled it and served it as a custom map layer. You can view it at https://finance.alisio-computing.eu https://finance.alisio-computing.eu
- degenerate 7y agoThanks for sharing! One more curiosity - what PNG compression tool was used and how long did it take to crunch 216GB to 17GB? I'm surprised it didn't crash.
- ghgr 7y agoI didn't compress an actual image from 216GB to 17GB. Instead, I created the highest resolution image already as a set of tiles (each one 5000x10000 px). Then I tiled them further in two additional zoom levels, until I got 4x8 square tiles of 1250x1250px. From there I worked backwards merging chunks of 2x2 tiles. The figure 217 GB comes from the cumulative size of all the pandas DataFrames containing the whole dataset (as mgspack files). The lossless compressed figure comes from the total size of the highest zoom level. It didn't take that long, it was mostly done overnight (so around 10 hours in a i7 server with 24 GB RAM).
- degenerate 7y agoThank you for the detail.
- drchickensalad 7y agoI don't think it'd be the static image because that downloads the entire thing. I assume they got some tiling work done to break it up.