Functions to Convert Native PostgreSQL geometric types to PostGIS
A set of functions that enable the conversion of the native PostgreSQL geometric types to PostGIS geometry objects.
Simon Greener
Converting PostgreSQL Native Geometric Types to PostGIS
Introduction I comes as a surprise to some that PostgreSQL has it own native geometric type system. The geometric types are documented here but the list includes: point – Point on a plane – (x,y) lseg – Finite line segment – ((x1,y1),(x2,y2)) box – Rectangular box – ((x1,y1),(x2,y2)) path – Closed path (similar to polygon)Read More
Fitting Bezier Polygon to Points
A colleague asked if I could implement the fitting of a 2D linestring to a set of points using a bezier approximation returning a polygon. The original implementation is Smooth a 2D polyline through a set of points by interpolation (Catmull-Rom) or approximation (Chaikin).. First off, we do a Chaikin smoothing (method 1) of aRead More
Fixing Geography Ring Orientation
This article demonstrates the effect wrong ring orientation has on the processing of a geography object and shows how to fix such orientation.
Calculating Distance in the Lambert Conformal Conic projection vs WGS84/GDA94
This article shows how scale is affected when calculating distances along the Lambert Conformal Conic Projection by comparing distances computed on the projection against those calculated along a geographic projection.
Killer Data
Back in 2005 I wrote two article on LiDAR. These articles are: Killer Data – Part 1 Killer Data – Part 2 Enjoy.
Delaunay Triangulation Function for TSQL and SQL Server Spatial
This article shows how to create a delaunay triangulation (mesh) from various inputs in SQL Server Spatial, and compute the 3D (slope) area.
Creating linestring geometries from a table of ordinates (SQL Server)
This article shows how to create linestring and mutlilinestring SQL Server geometry objects from a from table of ordinates.
Creating linestring geometries from a table of ordinates (Oracle)
Introduction (This article is about Oracle Spatial.) It is quite a common thing to have ordinates held as separate columns within a table as in the following CTE example. with cte as ( select 001 as asset_id, 1 as part_num,1 as vertex_num,0 as x,5 as y, 0 as m from dual union all select 001Read More
Partition Spatial Data using SQL Server
In this article a quad tree tesselation is used to define how to partition a table of based on its spatial data (geographic points) in SQL Server. The recursive spatial partitioning uses the spatial content to influence each grid cell size.