Linear referencing is a natural and convenient means to associate attributes or events to locations or portions of a linear feature. It has been widely used in transportation applications (such as for highways, railroads, and transit routes) and utilities applications (such as for gas and oil pipelines). The major advantage of linear referencing is its capability of locating attributes and events along a linear feature with only one parameter (usually known as measure) instead of two (such as longitude/latitude or x/y in Cartesian space). Sections of a linear feature can be referenced and created dynamically by indicating the start and end locations along the feature without explicitly storing them.
The linear referencing system (LRS) application programming interface (API) in Oracle Spatial and Graph provides server-side LRS capabilities at the cartographic level. The linear measure information is directly integrated into the Oracle Spatial and Graph geometry structure. The Oracle Spatial and Graph LRS API provides support for dynamic segmentation, and it serves as a groundwork for third-party or middle-tier application development for virtually any linear referencing methods and models in any coordinate system.
For an example of LRS, see Example of LRS Functions. However, you may want to read the rest of this chapter first, to understand the concepts that the example illustrates.
For reference information about LRS functions and procedures, see SDO_LRS Package (Linear Referencing System) .
This chapter contains the following major sections: