Thematic Earth
Geoplex
Spherical triangles covering a globe
by Read Write Tools
| Abstract |
|---|
| The geoplex tool is used to create GIS layers of nested spherical triangles based on a regular icosahedron model of Earth. Vertices, edges, faces, and centroids may be used in any GIS system that reads geojson, ICE, or GFE file formats. |
Motivation
Tiling the Earth with triangular faces has many uses. The motivation for this tool is the need to create faces that cover the entire earth, including the polar regions, with equal area tiles.
Installation
The geoplex utility uses Node.js. Package installation is done via NPM.
To install the utility and make it available to your Bash shell, use this command.
[user@host]# npm install -g geoplex
Usage
The software is invoked from the command line with:
[user@host]# geoplex --help
GEOPLEX creates geodetic triangles based on a regular icosahedron model of Earth
usage: geoplex generate [options]
geoplex convert [options]
options:
--terrasect=min,max minimum and maximum icosahedron cutting depth (from 0 to 6) to include in output files
--output= filename to write shapes to
--geometry= which type of geometry to generate ['all', 'vertex', 'edge', 'face', 'centroid']
--accuracy= digits to use for latitude and longitude coordinates 1 to 6 (1=11km, 2=1100m, 3=110m, 4=11m, 5=1.1m, 6=11cm)
--format= which file format to use ['geojson', 'ice', 'icebin', 'gfe', 'gfebin']
'geojson' standard geoJSON encoding
'ice' indexed coordinate encoding
'icebin' indexed coordinate encoding binary
'gfe' geographic feature encoding
'gfebin' geographic feature encoding binary
--properties which properties to include with each feature
'none','all',
'uid','parentUID',
'longitude','latitude',
'terrasect','edgeLength','triangularArea','bias'
'neighboringVertices','neighboringEdges','neighboringFaces','enclosingFace','neighboringCentroids',
'vertexA','vertexB','vertexC','centroid','face1','face2','face3','face4'
--topology print topology relationships
--statistics print statistical values
--verbose print extra topological and statistical details
--version
--help
Output
Terrasect depth
The tool generates points, lines and polygons that cover the entire Earth using nested terrasects. The initial terrasect covers the Earth with 12 vertices, 30 edges, 20 faces, 20 centroids. Each terrasect contains four times as many spherical triangular faces as its predecessor:
- terrasect 0 has 20 faces of 21,544,071 km² and 30 edges of 7,054 km
- terrasect 1 has 80 faces of 6,093,750 km² and 120 edges of 3,765 km
- terrasect 2 has 320 faces of 1,575,750 km² and 480 edges of 1,914 km
- terrasect 3 has 1280 faces of 397,341 km² and 1920 edges of 961 km
- terrasect 4 has 5120 faces of 99,550 km² and 7680 edges of 481 km
- terrasect 5 has 20,480 faces of 24,901 km² and 30,720 edges of 241 km
- terrasect 6 has 81,920 faces of 6,226 km² and 122,880 edges of 120 km
File formats
The generated output is in any of these GIS shape file formats:
- geojson - RFC 7946
- ice - Indexed Coordinate Encoding
- icebin - Indexed Coordinate Encoding binary
- gfe - Geographic Feature Encoding
- gfebin - Geographic Feature Encoding binary
Metadata
Dependencies
This library depends on iolib, softlib, gcslib, and gcsio.
Module exports
| ES modules | true |
| Common JS | false |
Suitability
| Browser | none |
| node.js | CLI and API |
Availability
 | Documentation | Read Write Hub |
 | Source code | github |
 | Package installation | npm |
License
The geoplex library is not freeware. After evaluating it and before using it in a public-facing website, eBook, mobile app, or desktop application, you must obtain a license from Read Write Tools as part of the thematic-earth DOM Component.
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