I am looking to create a d3 powered topographic map of a handful of countries. Topographical features across entire countries can be intricate and plotting them can be resource-intensive, because we are going over each locus across the entire surface area of the country. Since d3 is a client side library, I will be limited in the resolution I can plot in -- a page with many elements will be very slow or even crash-prone. For these reasons I will not be needing the most granular topographic data. Though, I suppose I can also use binning or other transformation to make things manageable.
To my knowledge satellite data is favorable for topographic cartography. However, the NASA or European space agency websites don't have any means of downloading this data. I'm not sure if there is a free data option at all or if I'm just inept at navigating their fancy website and deciphering all the smarty-pants "rocket-science" terms.
NASA or otherwise, is there an open data resource for plotting-from-scratch a reasonably detailed topographic map?
- It would be nice if the resource was already categorized by country, but I'm willing to slice the desired geographic region manually if need be (I imagine this will be a big headache though)
- intended use case is for a 2-dimensional d3.js map