Overview | Package | Class | Use | Tree | Deprecated | Index | Help
| deegree 2.4 (2010/11/11 10:47 build-27-official)
PREV PACKAGE NEXT PACKAGE | FRAMES NO FRAMES

## Package org.deegree.crs.projections

A map projection create a 2D view of the 3D-Object 'earth', by doing so, some information is inevitably lost.

See:
Description

Class Summary
Projection | Map `conversion` is the process of changing the map grid coordinates (usually, but not always, Easting & Northing) of a Projected Coordinate Reference System to its corresponding geographical coordinates (Latitude & Longitude) or vice versa.
ProjectionUtils | The `Utils` class combines some helpful constants and forms.

## Package org.deegree.crs.projections Description

A map projection create a 2D view of the 3D-Object 'earth', by doing so, some information is inevitably lost.

Because of this and because of the fact, the earth isn't a perfect sphere --or even a perfect ellipsoid for that matter--, there is no 'best' projection for the projection of every region on earth. Hence a lot of different mathematical projectional functions have been developed over the years. It is possible to categorize these functions into three groups:

- `Cylindric projections`
- `Conic projections`
- `Azimuthal projections`

## Automatic loading of projection classes

It is possible to create your own projection classes, which can be automatically loaded by the `DeegreeCRSProvider` class.

You can achieve this loading by supplying the `class` attribute to a `crs:projectedCRS/crs:projection` element in the 'deegree-crs-configuration.xml'. This attribute must contain the full class name (with package), e.g. <crs:projection class='my.package.and.projection.Implementation'>

Because the loading is done with reflections your classes must sustain following criteria:

### Projections

1. It must be a sub class of `Projection`
2. A constructor with following signature must be supplied:
   `public MyProjection(
   `GeographicCRS` underlyingCRS,
   double falseNorthing,
   double falseEasting,
   javax.vecmath.Point2d naturalOrigin,
   `Unit` units,
   double scale,
   java.util.List<org.w3c.dom.Element> yourProjectionElements
   );
   `

   The first six parameters are common to all projections (for an explanation of their meaning take a look at `Projection`). The last list, will contain all xml-dom elements you supplied in the deegree configuration (child elements of the crs:projection/crs:MyProjection), thus relieving you of the parsing of the deegree-crs-configuration.xml document.

Version:
  $Revision: 15008 $, $Date: 2007-03-20 10:15:15 +0100 (Di, 20 Mrz 2007)$
Author:
  Rutger Bezema, last edited by: $Author: rbezema $

Overview | Package | Class | Use | Tree | Deprecated | Index | Help
| deegree 2.4 (2010/11/11 10:47 build-27-official)
PREV PACKAGE NEXT PACKAGE | FRAMES NO FRAMES

an open source project founded by lat/lon, Bonn, Germany.
For more information visit: http://www.deegree.org