The USGS has stopped updating to their traditional 7.5′ paper quads, replacing them with a new product called US Topo, a reincarnation of their Digital Map – Beta product. This seems like a never ending source of confusion (I’m looking for a US Topo map. You mean a map of the US? No, a US Topo. […]
CalTopo has a slope analysis layer that can shade slopes by angle and aspect. You may or may not find it useful for planning safe travel routes in avalanche-prone terrain, and I make no claims that it is either accurate or useful for this purpose. However, if you do decide to use it for route […]
CalTopo map coverage for the contiguous (i.e. lower 48) United States is almost done. Given that the map layers are about to be refreshed, this seems like a good opportunity to write about what is currently available, and where the data comes from. First and foremost, USGS topo maps. CalTopo’s usgs layer is composed entirely […]
I’ve just added a contour line layer to CalTopo. Current coverage is California only, although it will be expanded to the western US during the next month or two. California provides its elevation data online; for the rest of the country, you actually have to mail a hard drive to the USGS. What is this, […]
A little bit of history . . . I decided to build CalTopo.com while standing in the Skeggs Point parking lot above Woodside, CA at 4AM in the summer of 2009. I’d just been headed to bed when the SAR pager went off for a missing hiker, so I sent a quick email to work […]
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