We’re pleased to announce worldwide elevation data by graduating our terrain-preview project into a fully supported Mapzen Terrain Tiles service!
Terrain tiles provide open elevation data for the entire world in a raster tile format. By aggregating, standardizing, and tiling multiple source datasets into common web mapping and desktop GIS formats and dimensions, it’s much easier to process the data and build applications on top of it.
Each square-shaped terrain tile contains a grid of elevation values. For example, the grid cell for Mount Everest would has a value of 8,848 meters above sea level, while the grid cell for Challenger Deep has a value of 10,994 meters below sea level.
With terrain tiles, you have the power to customize the content and visual appearance of your map on the fly and perform complicated analysis on the desktop or in the cloud. We’re excited to see what you build!
If you are familiar with digital elevation models (DEMs) or digital terrain models (DTMs), then you’ll be interested in Mapzen’s new Terrain Tiles service. Tiles are available for zooms 0 through 15 in several spatial data formats, including PNG and GeoTIFF tiles in Web Mercator projection, as well as SRTM-style HGT in raw latlng projection.
A derived “normal map” product is also available. We precompute the math on the server so renderers like Tangram can generate spheremap-based hillshades and real-time 3D scenes with these “normal” tiles, even on your phone.
Get an API key
To use the Mapzen Terrain Tiles service, you should first get a developer API key. Sign in at https://mapzen.com/developers to create and manage your API keys, it’ll only take a minute (or two).
- Go to https://mapzen.com/developers.
- Sign in with your GitHub account. If you have not done this before, you need to agree to the terms first.
- Create a new key, and optionally, give it a name so you can remember the purpose of the project.
- Copy the key into the terrain URL where
mapzen-xxxxxxxrepresents your key.
Tell me more
Complete documentation for the Mapzen Terrain Tiles service is available from: https://mapzen.com/documentation/terrain-tiles/
Endpoints
Mapzen terrain tile endpoints are:
https://tile.mapzen.com/mapzen/terrain/v1/terrarium/{z}/{x}/{y}.png?api_key=mapzen-xxxxxxxhttps://tile.mapzen.com/mapzen/terrain/v1/normal/{z}/{x}/{y}.png?api_key=mapzen-xxxxxxxhttps://tile.mapzen.com/mapzen/terrain/v1/geotiff/{z}/{x}/{y}.tif?api_key=mapzen-xxxxxxx*https://tile.mapzen.com/mapzen/terrain/v1/skadi/{N|S}{y}/{N|S}{y}{E|W}{x}.hgt.gz?api_key=mapzen-xxxxxxx
The earlier terrain-preview.mapzen.com endpoints announced March 22nd, 2016 will be retired effective January 1st, 2017. Please update your projects.
(*) 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 Public Dataset Endpoints
We’re proud to partner with Amazon to offer terrain tiles in their public dataset program on S3.
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}.pnghttps://s3.amazonaws.com/elevation-tiles-prod/normal/{z}/{x}/{y}.pnghttps://s3.amazonaws.com/elevation-tiles-prod/geotiff/{z}/{x}/{y}.tifhttps://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) - 32768Normal 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 3DEP 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 services
- Elevation query 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.
- Elevation influenced bicycle routing: https://mapzen.com/blog/making-the-grade-elevation-influenced-bicycle-routing/
- Walkabout outdoor map: https://mapzen.com/blog/walkabout/
Terrain timeline
- 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.
- We followed up with May’s What a Relief: Global Test Pilots Wanted letting you know about improved detail in the United States and official Tangram support.
- In early July we launched Walkabout, Mapzen’s signature outdoor cartography.
- In late July Geraldine explored the world of Sphere Maps based on the terrain data.
- In September Peter followed up again with a new Heightmapper tool to browse the terrain tiles and create heightmaps.
- Later in September we partnered with Amazon to release the raw data as new terrain public dataset.
- In October (that’s now!) we’re releasing v1 of the Mapzen Terrain Tiles service.
- NOTE: The existing terrain-preview.mapzen.com endpoints will be retired Jan. 1, 2017.
Feedback
Have any feedback on the terrain tiles? Please direct feedback to Nathaniel Vaughn Kelso, our Chief Cartographer, at tiles@mapzen.com!
