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From Jonathan mayer <jonrma...@yahoo.com.INVALID>
Subject Spatial Functions
Date Fri, 28 Dec 2018 11:10:04 GMT
 Hi All,
Over the last few days, I have started to develop new calcite spatial functions based upon
locationtech libraries - jts-core and proj4j - basically replacing the esri-geometry-api.

JTS is the Gold Standard and there are far more examples/templates out there from an algo
implementation perspective.
It is still early days yet - lots to do - but I have placed a project on GitHub - jonrmayer/geofunctions -
which contains all the code to date.

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jonrmayer/geofunctions

Contribute to jonrmayer/geofunctions development by creating an account on GitHub.
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 It is intended to be a like-for-like replacement of the existing calcite-core/runtime/GeoFunctions.java
file.
With some minor edits to calcite-master pom /calcite-core pom - it is feasible to drop this
in as a replacement - adding the calcite imports etc to the top of the file.
Tests however will be a problem - eg. spatial.iq will no longer be relevant. ESRI outputs
geometries to JSON whereas JTS outputs WKT - this will need to be rewritten.
My current plan is to focus on implementing as many functions as possible with basic tests
and then to improve on the (very) basic Maven testing before letting anyone know that I am
reasonably happy.
I should imagine that spatial.iq will have to wait a fair while - I will need it to test Geometry
Collections for eg ST_DWithin/ST_Collect etc and hope that the maven test are enough from
a confidence perspective.
A bit of background:- I have 10+ years in the GIS/spatial arena but only 1.5 years with Java
( very junior ) I know PostGIS/H2GIS/Oracle/SQlServer/OGR/NTS etc. - biased towards the former.
I know what I am looking for re: results. My recent focus has been developing Spatial Data
Flows within Apache Nifi - hence the interest in Calcite.
I would like to contribute to the project but I don't believe that I could ever become a "Contributor"
- I would mess it up.

I can build Calcite within my very narrow (Nifi) world view but do struggle with a full build.
I need the help of a master if there is an appetite to integrate this.
I think I have managed to extend the current spatial function coverage - I have added a "Status
Report" to the project - jonrmayer/geofunctions. I copied this from Calcite Documentation
and it is a bit of a shorthand. I have removed/replaced/added various funtions but it provides
a good overview.

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jonrmayer/geofunctions

Contribute to jonrmayer/geofunctions development by creating an account on GitHub.
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Regards,
Jonathan Mayer













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