The relief (hillshading) layer on OpenSnowMap.org have been updated. On the major part of the world, resolution jumps to 30m instead of 90m beforehand,thanks to the ongoing release of 1 arc-second SRTM data by NASA.
To mak a long story short, the relief is more precise by a x1.5 zoom factor.
For more details, here are the data used on the serveur to generate the hillshading.
Screenshot from USGS explorer on Google-map background
30m SRTM data are used where available. Up north, data comes from the EU-DEM for scandinavia, ASTER for Alaska, Canada, Greenland and Russia. In an area extending from Greece to Iran, I had to kept the 90m SRTM data from CGIAR, I hope to be able to update this area soon (done).
To assemble those datasets, I use a script based on python-gdal to merge the data by small 1×1° tiles, filtering SRTM data by a 3×3 average filter and ASTER by a 10×10 filter to reduce noise. Gdal utilities then re-assemble everythingin a big Tiff. For rendering, I took the opportunity to pre-calculate smaller Tiffs at lower zooms to reduce the load on the tile server. The map should showup more fluidly.
Contour lines will be updated from the same datasets, if I can optimize them enough to fit my disks.