Question about the data source

[xuezhicang]

Hello,

I noticed that the downloaded data is labeled as SRTM 30m Global 1 arc second V003. However, I believe the description may not be accurate. I've compared data from several regions downloaded using your code with DEM data from USGS Earth Explorer, and there are noticeable differences between them.

Could you clarify if the data source is actually Amazon Terrain Tiles? The description for Amazon Terrain Tiles, as shown on their website, can be found here:

https://aws.amazon.com/blogs/publicsector/announcing-terrain-tiles-on-aws-a-qa-with-mapzen/

Where does the data for the terrain tiles come from?

Mapzen aggregates elevation data from several open data providers, including 3 meter and 10 meter 3DEP (formerly NED or National Elevation Dataset) in the United States, 30 meter SRTM globally, and coarser GMTED zoomed out and ETOPO1 to fill in bathymetry – all powered by GDAL VRTs, and some special sauce. We’d love to add additional detail in your area, so send us data source tips!

If that is the case, could you please update the data description accordingly?

Additionally, it would be greatly appreciated if you could provide a method for us to download the actual "SRTM" DEM data directly.

Thank you.