MySQL Bugs: #46885: Polygon/line generalization feature

Bug #46885	Polygon/line generalization feature
Submitted:	24 Aug 2009 10:23	Modified:	8 May 2015 11:33
Reporter:	John Powell	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: GIS	Severity:	S4 (Feature request)
Version:		OS:	Any
Assigned to:	Assigned Account	CPU Architecture:	Any
Tags:	generalization, line, polygon, smoothing

Description:
This is a request for a polygon/line generalization algorithm. The generally used algorithm is Ramer-Douglas-Peuker. This algorithm can distort topology, producing intersections between lines in the generalized polygons that were not present in the original polygons. For this reason, two version are required:

1) Generalization
2) Generalization with an a posteriori check that the original topology has been maintained.

In postgres these functions are called ST_Simplify and ST_SimplifyPreserveTopology, while Oracle uses simplify_geometry and both use Douglas-Peuker. For the purposes of consistency, the term simplify should be used in some form.

How to repeat:
Feature request, so can't be repeated.

The input to this function would be the polygon/line to be simplified and some tolerance number.

Currently MySQL only supports projected/planar coordinates. Eventually, once geographic/geodetic coordinates are supported, this function would have to be modified somewhat in the calculation of distance as applied to tolerance.

Thank you for the feature request.

Posted by developer:
 
ST_Simplify was implemented in MySQL 5.7.6.