Licensing options for this format begin with FME Professional Edition.
The Mapzen Terrain Tiles on AWS reader provides FME with access to the Mapzen Terrain Tiles API, backed by Amazon Web Services (AWS).
Overview
Mapzen provides tiled terrain data though its Terrain Tiles API. The service is free to use, but requires registration with Mapzen to obtain an API key.
The data is available in 4 formats:
- Terrarium (PNG): A 24-bit fixed point representation of elevation in meters, split over the red, green, and blue bands. To decode:
(red * 256 + green + blue / 256) - 32768
- Normal (PNG): A 3-D vector representing the surface direction, and an 8-bit elevation value. The red, green and blue bands hold the x, y and z magnitudes, respectively. The alpha band contains quantized elevation data, with more opaque cells representing lower elevation. For more information on parsing this data, please see the Mapzen Terrain Tiles service documentation.
- GeoTIFF (GeoTIFF): Raw 16-bit integer elevation data in meters, suitable for analysis.
- Skadi (SRTM HGT): 16-bit elevation data in meters, in unprojected WGS84 coordinates.
Data Sources
Use of tiles from the Mapzen Terrain Tiles service for either analysis or display requires attribution. Please see the Attribution page for more information.
Tiles are provided by Mapzen, based on data from U.S. Geological Survey, and U.S. National Oceanic and Atmospheric Administration.
Specifically, the dataset is derived from the following open data sources:
- 3DEP (formerly NED) in the United States, 10 meters outside of Alaska, 3 meter in select land and territorial water areas
- SRTM globally except high latitudes, 30 meters in land areas
- GMTED globally, coarser resolutions at 7.5”, 15”, and 30” in land areas
- ETOPO1 to fill in ocean bathymetry at 1’
Please note that while the product may appear to be available at a high resolution, tiles will have been oversampled from coarser source data where finer resolution was not available.
Reader Overview
The reader downloads terrain tiles from Amazon S3 or the Mapzen Terrain Tiles API based on a spatial filter. The tiles are cached to disk and read by the underlying PNGRASTER, GEOTIFF or SRTMHGT format reader.
Mapzen Terrain Tiles are available through Mapzen’s international content distribution network (CDN), or directly from an S3 bucket in the AWS us-east region. The reader will automatically detect whether or not the workspace is running on an AWS EC2 instance in this region, and select the download location with the best performance. Note that an API key is required when connecting to the CDN.
FME Raster Features
FME raster features represent raster data and use several concepts that are unlike those used in the handling of vector data. The topics below describe how FME processes raster data.