Linear (measure positions along a path)

Linear can measure positions using distances along a path. This command specifies the path along which distances will be measured.

Select View > Axes > Coordinates and select the Linear system.

This method of measuring positions is sometimes used in applications such as Road maintenance.

Each position can be simply stated using a single number (plus a road name). The approximate position can be simply found by an engineer in the field by using a vehicle's tachometer (sometimes aided by milestones).

After selecting Linear coordinates, enter the path using a series of positions and use Enter to finish.

Future positions will be displayed in the Status Bar.

Example of placing positions at set distances along a path

To place a number of positions along the green LineString Item below:

Go to the View tab and select Coordinates > Linear:

Draw a line from the required start point to the end point. Double click to complete the line.

The line will trace the LineString Item between the start and end points.

TIP: It is not necessary to manually trace the LineString Item along its length.

Select Linear coordinates from Coordinates/Axes drop-down in the Status bar:

Go to the Create tab.

Click on Point (in the Simple group) and place a point at the required start position. The point will show as 0m in the position bar:

Enter 50m in the position bar and press Enter. The second point will be created at a distance of 50m from the start point:

Enter 100m in the position bar and press Enter. The third point will be created at a distance of 100m from the start point:

Enter 200m in the position bar and press Enter. The fourth point will be created at a distance of 200m from the start point.

Note: You can only enter a single value for each point, it is not possible to use multiple points at one time, i.e. 100m, 200m, 300m or 100m r 3 will not be recognised.

On completion the coordinate reference system can be returned to the original setting in the Coordinates/Axes drop down.

The images below show a practical use of the Linear command:

The crosses are the start and end points.

The circle symbols are the set distances from the start point along a road:

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