gahjogahjo
A little forge for your geospatial data. Simple, smooth and fast.
It makes hillshades, slopes and colour reliefs of elevation models too, matching GDAL’s. Here, Koli’s elevation model, coloured by height over its soft hillshade.
And city models: CityGML’s 3D buildings become CityJSON, FlatCityBuf or their footprints in any vector format. Here, the hotel on Ukko-Koli and its neighbours, read by gahjo from a FlatCityBuf.
Quick, and light on memory: the bars show how much of GDAL 3.12’s time and memory gahjo takes, on average, on the same machine. GDAL is the reference gahjo checks its results against. Less is more.
| Conversion | gahjo | GDAL | gahjo memory | GDAL memory |
|---|---|---|---|---|
| Forest stands → Shapefile | 3.7 s | 4.8 s | 22 MiB | 98 MiB |
| Forest stands → GeoJSON, reprojected | 38 s | 129 s | 23 MiB | 90 MiB |
| Forest stands → FlatGeobuf | 4.2 s | 3.6 s | 142 MiB | 254 MiB |
| Forest stands → GeoPackage | 3.8 s | 3.7 s | 66 MiB | 127 MiB |
| Map sheet index → FlatGeobuf | 0.33 s | 0.60 s | 54 MiB | 175 MiB |
| Elevation model → COG | 0.20 s | 0.27 s | 85 MiB | 360 MiB |
| 10 elevation model sheets → COG | 1.8 s | 2.5 s | 86 MiB | 396 MiB |
| Elevation model → ASCII grid | 0.49 s | 2.3 s | 36 MiB | 121 MiB |
| ASCII grid → COG | 0.46 s | 0.75 s | 82 MiB | 378 MiB |
| Orthophoto → JPEG | 0.66 s | 1.26 s | 175 MiB | 915 MiB |
| Orthophoto → PNG | 1.1 s | 8.9 s | 263 MiB | 516 MiB |
Desktop app on its way
Meanwhile, try it right here: drop a GIS file anywhere on this page, or .
GeoJSON, GeoPackage, Shapefile, GeoTIFF and more, one at a time or several together, merged into one if you like. It all runs in your browser; nothing is uploaded.
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Koli, from the National Land Survey of Finland’s elevation model, 3D buildings and orthophotos, CC BY 4.0
Made by otarvainen