We’re pleased to announce worldwide elevation data via a coverage upgrade to our terrain preview tiles. Additionally, in the United States 10 meter NED data now augments the earlier NED 3 meter and 30 meter SRTM data for crisper, more consistent mountain detail.

(Open Scotland full screen ➹ )

Back in March we previewed tiles in California with Peter’s Mapping Mountains post using a pre-release version of Tangram to generating hillshades client-side. That functionality has been finalized and is now available in Tangram v0.7 and Peter’s demos have been updated.

Excited about tiled raw elevation data but want take it back to your desktop GIS or use it in the cloud? A new 512x512 GeoTIFF option joins our earlier web and mobile PNG format raw elevation Terrarium and processed Normal tiles. It goes well with Mapzen’s Metro Extract, nudge nudge. Tired of Mercator? Skadi format tiles offer raw elevation tiles in latlng projection.

Give our preview elevation tilesets a test flight in your own applications, no API key required.

Endpoints

Terrain tile endpoints are:

• https://tile.mapzen.com/mapzen/terrain/v1/terrarium/{z}/{x}/{y}.png
• https://tile.mapzen.com/mapzen/terrain/v1/normal/{z}/{x}/{y}.png
• https://tile.mapzen.com/mapzen/terrain/v1/geotiff/{z}/{x}/{y}.tif
• https://tile.mapzen.com/mapzen/terrain/v1/skadi/{N|S}{y}/{N|S}{y}{E|W}{x}.hgt.gz

Tiles are available at zooms 0 through 14, with zoom 15 coverage filling out in the weeks to come.

(*) Note: GeoTIFF format tiles are 512x512 sized so request the parent tile’s coordinate. For instance, if you’re looking for a zoom 14 tile then request the parent tile at zoom 13.

Additional Amazon S3 Endpoints

If you’re building in Amazon AWS we recommend using machines in the us-east region (the same region as the S3 bucket) and use the following endpoints for increased performance:

• https://s3.amazonaws.com/elevation-tiles-prod/terrarium/{z}/{x}/{y}.png
• https://s3.amazonaws.com/elevation-tiles-prod/normal/{z}/{x}/{y}.png
• https://s3.amazonaws.com/elevation-tiles-prod/geotiff/{z}/{x}/{y}.tif
• https://s3.amazonaws.com/elevation-tiles-prod/skadi/{N|S}{y}/{N|S}{y}{E|W}{x}.hgt.gz

File formats

• Terrarium format PNG tiles contain raw elevation data in meters, in Mercator projection (EPSG:3857). All values are positive with a 32,768 offset, split into the red, green, and blue channels, with 16 bits of integer and 8 bits of fraction. To decode:

  (red * 256 + green + blue / 256) - 32768
  

• Normal format PNG tiles are processed elevation data with the the red, green, and blue values corresponding to the direction the pixel “surface” is facing (its XYZ vector), in Mercator projection (EPSG:3857). The alpha channel contains quantized elevation data with values suitable for common hypsometric tint ranges. High alpha channel values indicate lower elevation values (below sea level), making them more opaque.

  Specifically, normal format alpha values are counted in (floored) elevation increments. Below sea level they start at -11,000 meters (Mariana Trench) and range to -1,000 meters in 1,000 meter increments, with more detail on the coastal shelf at -100, -50, -20, -10 and -1 meters and finally 0 (intertidal zone). Values above sea level are reported in 20 meter increments to 3,000 meters, then 50 meter increments until 6,000 meters, and then 100 meter increments until 8,900 meters (Mount Everest).

• GeoTIFF format tiles are raw elevation data suitable for analytical use and are optimized to reduce transfer costs in 512x512 tile sizes but with internal 256x256 image pyramiding, in Mercator projection (EPSG:3857). Allow for the larger tile size by referring to the tile coordinate of {z-1} parent tile.

• Skadi format tiles are raw elevation data in unprojected latlng (EPSG:4326) 1°x1° tiles, used by the Mapzen Elevation Service. Essentially they are just the SRTMGL1 format tiles but with global coverage. See the SRTM guide for exact format specifications.

Data sources

Mapzen aggregates elevation data from several open data providers including 3 meter and 10 meter NED in the United States, 30 meter SRTM globally, and coarser GMTED zoomed out and ETOPO1 to fill in bathymetry, all powered by GDAL/OGR VRTs and some special sauce.

Could we provide better coverage in your area? Please recommend additional open datasets to include by filing an issue.

Related service

To query elevation at a single point or along a path almost anywhere in the globe, sign up for an API key and check out the Mapzen Elevation Service.

Feedback

Have any feedback on the tiles? We’re all ears during this extended “beta” preview of elevation tiles. Please direct feedback to Nathaniel Vaughn Kelso, our Head of Data & Cartography, at hello@mapzen.com!

_CORRECTION: This post was updated on 2016.05.03 to detail additional S3 endpoints and clarify GeoTIFF file extension as .tif with one f instead of two.

UPDATE Jan 19, 2017: We’ve also deprecated the terrain-preview beta endpoints and have updated this blog with the proper URLs_