Questions tagged [dggs]
Questions related to Discrete Global Grid Systems (DGGS)
14
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How does the ISEA-projection work? Looking for a didactic algorithm description
Is it a direct projection on 20 faces or on 32 faces?
Can I use PostGIS (with ISEA) to calculate and obtain cell-identifiers? For hexagons (like Uber H3) or for diamonds (like DGGRID's ISEA4D).
The ...
- 2,252
-1
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1
answer
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H3 Hexagon Geometry join on MSA Geometry
I have a pandas DataFrame with h3 hex ids and corresponding Polygon geometries and a geojson file with Texas Metro Area Geometries.
I'd like to join the H3 hex ID to Metro area and identify which ...
- 473
3
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1
answer
312
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How to obtain the minimal covering of a circle with H3 hexagons?
Given an EPSG:4326 lon,lat coordinate pair, and a radius r in meters, I want to find the smallest set of H3 hexagons at resolution res that completely covers the circle centered at lon,lat with radius ...
- 231
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0
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354
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Safe upgrade of PROJ for PostGIS?
Is there a safe way to install fresh PROJ, for example v8.2, in a Debian Linux server, for use with (for example) PostGIS v3?
The installation of PROJ was implicit in the PostGIS's, I never do ...
- 2,252
3
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3
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Converting line to set of H3 hexagons?
What is a proper way to convert a GeoJSON linestring to a set of H3 hexagons?
I came up with an algorithm where I
extract points from a line,
calculate an H3 hexagon of these points geo_to_h3
connect ...
- 133
4
votes
2
answers
272
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How to use ISEA projection?
The projection named ISEA - Icosahedral Snyder Equal Area has a (supposedly) good implementation in the PROJ Library, proj.org/isea, that is used by PostGIS, QGIS, etc. The example is agnostic - was ...
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2
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3
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2k
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Distorted h3 hexagons using h3js with Mapbox
When a user clicks on a Mapbox streets-v11 map, I'm attempting to:
Take the clicked point, and identify the h3 hexagon (at resolution 10) around the point
Convert the hexagon coordinates into the ...
- 121
8
votes
1
answer
202
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Why are my icosahedron triangle subdivisions not equilateral (PostGIS)?
I am creating a geodesic polyhedron using PostGIS. I am dividing the base icosahedron points (see Appendix A), into the first level of Class I subdivisions.
The setup
For simplicity let's take just ...
- 183
5
votes
0
answers
404
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Generate global grid of circles with minimum overlap with PostGIS
I want to generate a table of geometry points in PostGIS which represent the centers of circles, each with the same radius of X meters, that together form a "grid" that covers the entire ...
- 183
6
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1
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DGGS projections with PostGIS or pgLatLon
Important DGGS projections (like ISEA4T, ISEA4D or ISEA7H variants of ISEA) are free at https://github.com/sahrk/DGGRID , the DGGRID Software Project,
but I not see how to use it with PostGIS. Only ...
- 2,252
4
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1
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156
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Is there a FOSS implementation for Discrete Global Grid System & Global Statistical Geospatial Framework?
This 2019 document, "GSGF Europe -Implementation guide for the Global Statistical Geospatial Framework in Europe" describes the harmonization of two standards:
INSPIRE D2.8.I.2_v3.1 of year 2014;
OGC'...
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1
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0
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188
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Is there a piecewise-UTM coordinate system?
Is there an EPSG code, WKT or a proj4 string, for a single global piecewise-UTM coordinate system such as MGRS (the NATO military grid reference system)?
I suppose this would work similar to the ...
- 476
4
votes
1
answer
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Uber H3 DGGS: Table of largest hexagons per resolution?
I'm evaluating the use of H3 as a DGGS for a project, and so far I've been unable to find any reference of the area of the largest and smallest hexagons in the grid at each resolution. The "official" ...
- 247
5
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2
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Hex grid on EPSG:4326 globe (for use in Leaflet)
I'm looking for a way to evenly distribute a hexagon grid (x,y,z) on the EPSG:4326 globe. Knowing this is not mathematically possible I'm accepting the following limitations:
Poles don't need ...
- 311