Example Project Recommended Coordinate Systems Usage

This example shows how an expert user can guide the typical user by designating a list of available choices for coordinate system use within the project.

The portion of the database used to load this example is shown in Figure 3 below.

Figure 8 Project Recommended Coordinate Systems Usage

Reference Scope Data, - R_COORDINATE_REF_SYSTEM, R_CARTO_TRANSFORM

Creation of coordinate system reference data follows the pattern described above in the section EXAMPLE COORDINATE SYSTEM USAGE.

Project Scope Data � PROJECT_RECOMMENDED_CRS

A geodetic expert can create a list, valid for the scope of a project, that contains the set of likely standard 2D coordinate systems that should be used in the scope of a project. This should include all likely original coordinate systems that will be encountered and transformed to the storage coordinate system. The purpose of this list is to limit the complexity of possible coordinate system choices the typical user must confront and it is not used to limit the available choice of coordinate systems that are used to tag business data with valid coordinate systems.

Table 7 PROJECT_RECOMMENDED_CRS

Project Scope Data � PROJECT_RECOMMENDED_XFORM

A geodetic expert can create a list, valid for the scope of a project, that contains the set of likely standard geodetic datum transformations for coordinate systems pairs. This should include all likely transformations and the conditions for their use. The purpose of this list is to limit the complexity of possible coordinate system transformation choices the typical user must confront and is sometimes referred to as a "conflagration policy."

Table 8 PROJECT_RECOMMENDED_XFORM

Loading Sequence

1.          The PROJECT_RECOMMENDED_CRS instance is loaded by foreign key reference to a valid R_COORDINATE_REF_SYSTEM. If extensions are needed in R_COORDINATE_REF_SYSTEM, they must conform to the ESRI ArcSDE rules to be viable with the spatial utilities. Here the purpose of an instance may be for documentation of integration with other spatial utilities, such as Mentor or Blue Marble; they can be added with the understanding that they cannot be used for persistent storage of actual business data. The responsibility for creating this list is with an expert user or the company Geodesist.

2.          Create an instance of PROJECT_RECOMMENDED_XFORM with foreign key references to PROJECT_RECOMMENDED_CRS for the From and the To coordinate system and to R_CARTO_TRANSFORM for the Transformation method.