Elk is a set of tools to generate map and topographical surfaces using open source data from OpenStreetMap.org and USGS.
OpenStretMap.org is an open/crowd sourced website of mapping data. It allows you to export XML formatted data of a selected area and then Elk will organize and construct collections of point and tag data so that you can begin creating curves and other Rhino/Grasshopper geometry.
The Location component is primarily for preprocessing all of the node or point data from the OSM export. It wants a file path to an OSM file as it's input and will output OSMPoints, a Point3d with an OSM defined ID, the text string of the full XML file, and the latitude and longitude domains.
The OSMData component is what you use to start organizing and collecting the data from the OSM file. It defaults to selecting Building elements, but can be changed to select from any of the other map features in the OSM spec.
USGS is a science organization that provides access to a large range of scientific data pertaining to the earth. Elk uses data that originates from the Shuttle Radar Topography Mission (SRTM) of 2000. This was a shuttle mission where most of the earth was scanned for elevation and packaged in 1°x1° tiles.
The Topography component can be used to generate points, curves, and a surface from various digital elevation model (DEM) file formats. It currently accepts IMG files at a resolution of 1/3 arc second, GeoTIFF files at a resolution of 1 or 3 arc seconds, and HGT files at a resolution of 1 or 3 arc seconds.
The higher resolution IMG files are available for the United States only and can be downloaded from the USGS National Map Viewer. GeoTIFF files are available for 1 and 3 arc second resolutions for most of the earth and can be downloaded from the USGS Earth Explorer. HGT files are the least reliable files as they tend to contain holes in the data, but they are the most basic form of DEM and you can download them from here.
- Download the ZIP file containing all of the Elk and GDAL library files.
- Right-click the ZIP file > Properties > make sure there is no "blocked" button
- Unzip the downloaded file
- In Grasshopper, choose File > Special Folders > Components folder.
- Elk's Topography component uses the Geospatial Data Abstraction Library to read the GeoTIFF and IMG files so it will contain a larger number of files that pervious versions. For this reason it is recommended that you copy the Elk folder with all of it's GHA and DLL files to this Libraries folder rather than the individual files.
- Restart Rhino and Grasshopper