
Open-Source Clojure Library for Geospatial Information - dirtyvagabond
http://blog.factual.com/open-source-clojure-library-for-geospatial-information
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malandrew
For those that don't recognize the name on the blog post, this is aphyr, who
has been publishing the excellent "call me maybe" technical posts.

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ovis
This is excellent news. Without knowing much clojure or looking deeply into
the source, I wonder if or how this project does or plans to handle
projections and coordinate systems? I find this capability to be among the
really important things that geospatial libraries provide.

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jandrewrogers
This is great news and I applaud the work. The state of open source for
geospatial geometry has frequently been fragmented and dodgy at best so this
effort to unify it are a step forward. PostGIS is the crown jewel of open
source for GIS processing but a broader set of tools is much needed.

The only caveat looking at this is that the geometry computation is not
suitable for some types of geospatial analytics. This has been a persistent
gap in open source geospatial tools. The challenge is that closing this gap is
a pretty esoteric topic in applied mathematics that only a handful of people
are really qualified to address and few of them seem to be contributing to
open source. Still, any progress is good.

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prospero
Can you expand on what the esoteric topic is and its application?

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dagw
Translating between coordinate systems and basically anything that involves
mapping and measuring in 3 dimensions on an irregular not-quite-spherical
surface is really hard to get right.

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jimktrains2
I didn't make this picture, but it gives a good idea on the "irregular not-
quite-spherical surface" part.

[http://alienspacesciencenews.files.wordpress.com/2013/10/an-...](http://alienspacesciencenews.files.wordpress.com/2013/10/an-
example-of-the-spatial-relationship-between-a-local-datum-a-global-datum-and-
the-geoid-is-represented-in-the-following-figure-wgs84.gif)

The Local Datum could be NAD83 or what-have-you based on where you are on the
surface. Using the local datum gives better distance measurements and more
accurately can represent elevation.

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dagw
That's a pretty great image. I'll have to remember it for next time someone
asks why is all this so hard and can't we just use WGS84 for everything.

