# GetSpatialReferenceFromExtent Method

## Description

Gets the spatial reference for an extents within a spanned cube in a Coordinate Reference System.

## Syntax

Visual Basic |
---|

Public Function GetSpatialReferenceFromExtent( _ ByVal |

## Parameters

*x1*- The first
*x*coordinate of the cuboid extent to be queried. *y1*- The first
*y*coordinate of the cuboid extent to be queried. *z1*- The first
*z*coordinate of the cuboid extent to be queried. *x2*- The second
*x*coordinate of the cuboid extent to be queried. *y2*- The second
*y*coordinate of the cuboid extent to be queried. *z2*- The second
*z*coordinate of the cuboid extent to be queried. *projection*- The named
**Coordinate Reference System**used in the calculation of the spatial reference. This can be defined as: - OGC URNs (eg 'urn:ogc:def:crs:OGC:1.3:CRS84')
- EPSG URNs (eg 'urn:ogc:def:crs:EPSG::27700')
- EPSG code strings (eg 'EPSG:27700')
- EPSG URLs (eg 'http://www.example.com/epsg#27700' or 'http://www.example.com/epsg.xml#27700')
- EPSG codes as a simple string (eg '27700')
- If blank, this will default to the current 'axes' CRS.
*span*- The span of the cube used in the calculation of the spatial reference.

## Return Type

A 16 character string which encodes a spatial reference.

## Remarks

The spatial reference string encodes a position and a radius which together describe an extentâ€™s circle.

The span used when calculating a spatial reference must be big enough to cover all of the possible coordinates. A smaller span will give spatial references with a finer resolution. The spatial reference does not affect the accuracy or resolution of the positions of the Item it is associated with, only the accuracy of whether or not the **Item** is loaded in a particular view.

The worst that can happen with a coarse resolution is that extra items are loaded.

* Available:* GEO OD SISpy

*Groups:*

## Example

SpatRef = *sis.*GetSpatialReferenceFromExtent (540000, 230000, 0, 540123, 230234, 0, "*APrjNatGrid", 2000000)

Returns the spatial reference an item whose extents are as shown above (see also GetExtent) based on the National Grid coordinate reference system, within a 2 000 000m cube.