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GeoJSON

geojson.org

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21–30 of 78 posts

Re: GeoJSON

#21

Post by kijin »

mtucker502 wrote: post #9

The properties key is plural but contains a dictionary. Does the schema allow for this to be a list?

Nope, properties must be an object (dictionary or null). Which means each property can only appear once.

The spec doesn't say what type the value of a property can be, though. Examples in the RFC show strings, floats, and a nested object. So you could probably put a list in there as well if you want to store multiple values under the same key, provided that your decoder knows what to do with such values. (GeoJSON is often converted to and from WKB/WKT, and unorthodox values may be lost in the conversion.)

Re: GeoJSON

#23

Post by trgn »

nice and simple, great. but because it's json, most parsers are horribly inefficient, which is tough, because a lot of geodata is massive.

Re: GeoJSON

#24

Post by flir »

sam_lowry_ wrote: post #2

Dunno whose website this is, but the format itself is great, and it allows for a relatively compact and relatively human-readable presentation. A few weeks ago I (vibe)coded mxmap.be and if not for the ubiquity of geojson, it would have taken me significantly more effort.

What a great project.

I vibe coded something similar (different data source) with codex that went something like SQLite->GeoJSON->Leaflet and it was a dream - almost no corrections necessary. It even went off and found a really nice colour scheme for me.

Re: GeoJSON

#25

Post by biosboiii »

I love GeoJSON :) You can bring any Geo/GIS from 0 to visualization by just parsing it into GeoJSON.

geojson.io is a great editor/viewer by Mapbox. Also https://kepler.gl/demo is great for additional filtering, visualizations like heatmaps, arcs etc.

A extension to GeoJSON that works with JSONL-like semantics would be great for huge files, but this could also be solved by tiling.

Re: GeoJSON

#27

Post by jtbaker »

nobleach wrote: post #22

We used this extensively when I worked in this space (2010 - 2014). My favorite addition was using https://github.com/topojson/topojson to add arcs. That cut down on quite a bit of points to represent curves.

Dang, fun memories of when I was first getting in to geo/data stuff and doing a lot of web mapping stuff with D3, Leaflet and friends. Seems as tools like Vector tiles/PMTiles have supplanted topojson for a lot of visualization oriented use cases.

Re: GeoJSON

#28

Post by phillc73 »

GeoJSON is not just for geographical features! Shapes of any kind work just as well.

QuPath[1], a tool for digital pathology whole slide image analysis, can export annotations in GeoJSON format (and import too I suppose).[2] This makes it really very easy to make annotations transportable between tooling.

[1] https://qupath.github.io/

[2] https://github.com/qupath/qupath-docs/blob/main/docs/advance...

Re: GeoJSON

#29

Post by Stratoscope »

One task where GeoJSON falls down is simplification of a group of polygons with common boundaries, e.g. the 48 conterminous US states. If you start with a highly detailed set of polygons, you need to simplify them for practical display in an online map.

GeoJSON doesn't encode the fact that the boundary points are common between adjacent polygons. When you simplify those polygons, each one is handled separately, and you end up with "slivers" where the boundaries are misaligned:

https://www.bing.com/images/search?q=map+slivers+betwen+poly...

TopoJSON solves this by encoding each such boundary only once. So when you simplify the polygons, they are all done together, and the same simplification applies to adjacent polygons. No more slivers!

https://github.com/topojson/topojson

https://github.com/topojson/topojson-simplify

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