> I've read somewhere that the srtm data has, at best, 30m resolution. I don't > know that it's resolved enough for hiking/snowshoeing/cross-country skiing? I > can think of features where greater than 30m resolution would be helpful. > Then again, I just looked at opencyclemap for that area again, and the > resolution might be plenty. I'll have to look again.
SRTM is handy since it is a global dataset with coverage from 54 degrees south to 60 degrees north. But globally, it is released only at 3 arcsecond resolution (approximately 90 m), though for the US, it's available at 1 arcsecond (30m). For localized areas, there are other options - the National Elevation Dataset (NED) in the US is generally good to around 1/3 arcsecond (10m), with some localized spots down to 1/9 arcsecond (3m). In Canada, the Canadian Digital Elevation Data (CDED) is available to 3/4 arcsecond (23m). Another resource at much lower resolution is GTOPO30, which is only to 30 arcseconds (approximately 1000m) but has the advantage in that it is truly pole to pole, so fills in the northern and southern regions that SRTM didn't cover. So if high accuracy publicly available elevation data is required, and you have some time on your hands, it's possible to create an elevation dataset spanning the globe using "best of" data from multiple datasets. That's what I did for the elevation data I use in the Mapster app I made, though it can be a fairly intensive process (I used overlaps in the data to confirm sections, identify problem areas, fill voids in one dataset with data from another, etc), and there are sometimes a few small discontinuities in boundary areas, due to different accuracies of mapping techniques, possibilities of slightly different interpretations of datum, etc. But overall, I can speak from experience that it is possible, and you can benefit from higher resolution than 30m in many parts of the world if it's useful to you. Dan _______________________________________________ Talk-ca mailing list Talk-ca@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-ca
