geodesic polygon buffer

[morganherlocker]

No description provided.

[aparshin]

Hello Morgan,

I've implemented a prototype of geodesic buffer here: https://github.com/aparshin/turf-buffer/tree/geodesic
There is a Leaflet page for debug added there, but it requires to browserify sources (browserify index.js --standalone buffer > bundle.js).

The algorithm is simple: manually construct geodesic buffers for each line segment (taken from artisinal branch) and then union them using JSTS (CascadedPolygonUnion can be used to speedup things a little).
There are couple issues with this implementation:

• More accurate segment buffer should be constructed for long segments (in fact, it is more theoretical issue then real use case)
• The algorithm is really slow!

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We had implemented similar algorithm in our Web-GIS and faced performance problem. Here is my question in JSTS mailing list about possible faster algorithms: http://sourceforge.net/p/jts-topo-suite/mailman/message/31906899/

I think the following variant will be faster for small and medium-size geometries:

• split geometry into small enough pieces (relative to the Earth size)
• project each peace to local orthographic projection
• apply classical buffer from JSTS
• project resulting buffer back to geographic projection
• union buffers

What do you think about this? Maybe, you have any other ideas?