1. Seth G
  2. SQL Server Spatial Tools

Overview

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** 0: Contents
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1: Introduction
2: Installation
3: Features

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** 1: Introduction
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This project is a collection of tools for use with the spatial types
that are new to SQL Server 2008. This project does not provide an 
end-user application, but rather a set of reusable functions which 
applications can make use of.

Development of this package is hosted at CodePlex:
http://www.codeplex.com/sqlspatialtools.  Source is available at
this site.

This package is licensed under the Microsoft public license. See
http://www.codeplex.com/sqlspatialtools/license or the included
License.txt file for details.

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** 2: Installation
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This package contains a single assembly, SQLSpatialTools.dll
This assembly can be included and used directly from a .NET 
application, or can be registered and used from within SQL Server
2008.

Scripts for registering and unregistering the functionality in
SQL Server 2008 are included in the SQL Scripts directory.

Detailed Steps:

To Register:
1) Note the path to the SQLSpatialTools.dll file.
2) Edit the Register.sql file in the SQL Scripts directory:
  a) Insert the name of the database you are registering the 
     functionality to where indicated at the beginning of the script.
  b) Insert the path to the SQLSpatialTools.dll file where indicated
     at the beginning of the script.
3) Execute the script on your SQL Server 2008 instance.

To Unregister:
1) Edit the Unregister.sql file in the SQL Scripts directory and insert
   the name of the database use are unregistering the functionality
   from where indicated at the beginning of the script.
2) Execute the script on your SQL Server 2008 instance.

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** 3: Features
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Scripts
-------
Several scripts are included in the SQL Scripts directory. These include
scripts for registering and unregistering all of the following
components, as well as several examples of their use.

Functions
---------
These static methods, implemented in the class Functions, can both be
registered in SQL Server and used through T-SQL, as well as be used
directly from the CLR:

bool IsValidGeographyFromGeometry(SqlGeometry geometry)
Check if an input geometry can represent a valid geography without throwing an exception.
This function requires that the geometry be in longitude/latitude coordinates and that
those coordinates are in correct order in the geometry instance (i.e. latitude/longitude
not longitude/latitude). This function will return false (0) if the input geometry is not
in the correct latitude/longitude format, including a valid geography SRID.

bool IsValidGeographyFromText(string inputWKT, int srid)
Check if an input WKT can represent a valid geography. This function requires that
the WTK coordinate values are longitude/latitude values, in that order and that a valid
geography SRID value is supplied.  This function will not throw an exception even in
edge conditions (i.e. longitude/latitude coordinates are reversed to latitude/longitude).

SqlGeography MakeValidGeographyFromGeometry(SqlGeometry geometry)
Convert an input geometry instance to a valid geography instance.
This function requires that the WKT coordinate values are longitude/latitude values,
in that order and that a valid geography SRID value is supplied.

SqlGeography MakeValidGeographyFromText(string inputWKT, int srid)
Convert an input WKT to a valid geography instance.
This function requires that the WKT coordinate values are longitude/latitude values,
in that order and that a valid geography SRID value is supplied.

SqlGeography ConvexHullGeography(SqlGeography geography)
Computes ConvexHull of input geography and returns a polygon (unless all input points are colinear).

SqlGeography ConvexHullGeographyFromText(string inputWKT, int srid)
Computes ConvexHull of input WKT and returns a polygon (unless all input points are colinear).
This function does not require its input to be a valid geography. This function does require
that the WKT coordinate values are longitude/latitude values, in that order and that a valid
geography SRID value is supplied.

SqlGeography DensifyGeography(SqlGeography g, double maxAngle)
Returns a geography instance equivalent to its input, but with no two
consecutive points spaced more than maxAngle apart.

SqlGeography InterpolateBetweenGeog(SqlGeography start, 
  SqlGeography end, double distance)
Takes start and end geography points and returns a new point that is a
given distance from the start toward the end.

SqlGeometry InterpolateBetweenGeom(SqlGeometry start, SqlGeometry end,
  double distance)
Takes start and end geometry points and returns a new point that is a
given distance from the start toward the end.

SqlGeography LocateAlongGeog(SqlGeography g, double distance)
Takes a geography linestring and finds the point a given distance along
it.

SqlGeometry LocateAlongGeom(SqlGeometry g, double distance)
Takes a geometry linestring and finds the point a given distance along
it.

SqlGeometry ShiftGeometry(SqlGeometry g, double xShift, double yShift)
Takes a geometry instance and shifts if by a given X and Y amount.

SqlGeometry VacuousGeographyToGeometry(SqlGeography toConvert,
  int targetSrid)
A special case of the equirectangular projection, taking each point
(lat,long) --> (y, x).

SqlGeography VacuousGeometryToGeography(SqlGeometry toConvert,
  int targetSrid)
The inverse of the VacuousGeographyToGeometry projection.

Types
-----
These types can be registered in SQL Server or used directly through the
CLR.

SqlProjection
This class provides an extensible access point to various projections and
inverse projections. See the file projection_example.sql for a sample of
its use. Currently supported projections are:

    * Albers Equal Area
    * Equirectangular
    * Lambert Conformal Conic
    * Mercator
    * Oblique Mercator
    * Tranverse Mercator
    * Gnomonic


AffineTransform
This provides general affine transformations. See the example
transform_example.sql for a sample of its use.

Aggregates
----------
While implemented as classes, aggregates are essentially functions that
take a collection of inputs to a single result.

GeographyUnionAggregate
This aggregate finds the union of a set of geographies with an optional
additional buffer.

GeometryEnvelopeAggregate
This aggregate finds the envelope that contains a set of input
geometries.