Working with traverses

Traverses in ArcPad enable you to create polylines and polygons using offsets. In ArcPad, there are two types of traverses: Linear traverse and Radial traverse.

Linear traverse

A linear traverse enables you to capture the vertex of a polyline or polygon starting from a known point as you walk along a traverse. In other words, you begin at a known reference point, capture vertex A, move to vertex A, capture vertex B, move to vertex B, capture vertex C, and so on. Within a linear traverse, you use an automatic moving reference point, that is, the last vertex you captured.

You can capture vertices in a linear traverse using foresight or backsight. With foresight, you are standing at a known coordinate, such as reference point A, and you are shooting the target, such as the vertex of your feature. With backsight, you are standing at your target, such as the vertex of your feature, and you are shooting back to a known coordinate, such as reference point A. Use the Options page on the Point/Vertex dialog box to set foresight or backsight.

Illustration of foresight and backsight

Radial traverse

When you capture a radial traverse, you begin at a known reference point and capture the vertices around the perimeter of that reference point. You are always standing at the same fixed position while you are capturing multiple vertices. If your known reference point is a GPS location, variation in the GPS signal may impact your reference point accuracy.

The diagram below shows how a vertex in a line is calculated using a linear traverse versus a radial traverse, using one or two reference points.

Linear traverse

Radial traverse with one reference point

Radial traverse with two reference points

Other options for offsets

When working with offsets, you can set other options or parameters on the Options page on the Point/Vertex dialog box or in the GPS preferences. These parameters are typically considered constants versus the parameters you would set to calculate individual offsets such as slope distance, vertical distance, horizontal distance, and inclination.

Constant parameters may be set at the beginning of a data collection task and only changed as needed. The following are set on the Options page on the Point/Vertex dialog box:

9/23/2019