Essential linear referencing system vocabulary
Below are terms that are encountered when working with linear referencing systems.
Dynamic segmentation
动态分段是沿路径要素计算事件表中所存储和管理事件的地图位置以及在地图上显示它们的过程。术语动态分段源于每次更改属性值时无需分割(也就是“分段”)线要素的理念,即可以“动态”定位线段。
利用动态分段,可将多组属性与现有线状要素的任意部分相关联,无论其开始或结束位置为何。可以显示、查询、编辑和分析这些属性,而不会影响基础线状要素的几何。
Events
事件是指沿路径要素出现的线状要素、连续要素或点要素。路径要素上出现的或描述路径要素的任何事物都可以是事件。在运输字段中,事件示例可能包括路面质量、事故地点和速度限制。事件存储在事件表中。
Event tables
事件表包含有关资产、条件和可以沿路径要素定位的事件的信息。表中的各行引用事件,并且其位置表示为沿路径要素的测量值。共有两种类型的路径事件表:点事件表和线事件表。
Linear referencing method
A linear referencing method (LRM) is a system of measure for linear features that are represented as an offset from a known location along the length of a given feature. LRMs can be offsets from milepost locations along a highway, a measured distance from a known starting point, or a distance and direction from an asset location. LRMs are usually represented as a unit of measurement, such as miles or kilometers, but they can also be unitless, such as address ranges or a proportion.
M-value
添加到线要素的测量值。M 值以各顶点的 m 坐标的形式存储在路径要素中。M 值用于沿线要素测量距离。
Measure
沿线状要素存储的表示与要素起点(或沿线状要素的某点)相对位置的值,而不是以 X,Y 坐标形式表示。测量值以 m 值形式存储在路径顶点中。测量值可以采用任何测量单位,例如,英里、米和倍。
Route
路径是指具有唯一标识符和测量系统的任何线要素,例如,街道、公路、河流或管道。路径存储在路径要素类中。
Within Production Mapping, a line feature is only referred to as a route if it has a unique identifier and has measure values (m-values).
Route feature class
路径要素类是指在单个要素类中存储的具有通用测量系统的路径的集合(例如,某县所有公路的集合)。路径要素类与标准线要素类的区别是,除 x 和 y 坐标外,它还存储 m 坐标 (x,y,m)。
Straight line diagram
A diagram of a linear referencing route feature where the route is depicted as a straight line instead of showing the geometry of the feature. Such diagrams include one straight line to represent the route and additional rows above or below the route to depict events or features along the road. Straight line diagrams are often used for highway or pipeline management.