Command Description
The Simplify Linestrings command allows you to select one or more lines and remove unnecessary segments from the lines as well as convert horizontally chorded linework to curvilinear linestrings if possible. This is ideal for converting segmented road centrelines into true arc geometry so that a clean alignment string can be made.
- Click in the Linestrings selection field and then in a graphic view select the linestrings you want to simplify. Click Options for additional selection options.
-
Line/Arc tolerances:
- Maximum offset (line) – The straight-line tolerance checks how far points can drift from a straight path before the segment has to stop. The algorithm keeps adding points to the line as long as they stay close enough, measuring the shortest distance from each point to the ideal line. If any point strays too far, it cuts off the segment at the last good point to keep it looking straight.
- Maximum offset (Arc) – The arc tolerance makes sure a curve follows the original shape without bending too much. It tries different arc fits, checking how far the new curve deviates from the original path. If the difference is too big, it either adjusts the arc or switches back to a straight line to keep things accurate.
-
Additional settings:
- Replace lines with arcs - Check this box so that the command tries to fit curves to a series of straights chords.
- Maximum radius – Enter a value that you consider to be the largest radius that would be encountered in the selected linework, to help it determine when nodes should be considered to be a straight verse an arc.
-
Create linestring:
-
Layer name – Enter a suffix for the new layer name behind the placeholder of either {layer} or {name} which can be changed by clicking the right mouse button to insert the placeholder
{name} – This will use the name of the line selected.
{layer} – This will use the layer name of the line selected. - Color – select a colour for the new lines.
- Delete existing – Check this box if you want to delete the original lines being optimised.
-
Layer name – Enter a suffix for the new layer name behind the placeholder of either {layer} or {name} which can be changed by clicking the right mouse button to insert the placeholder
- Report – The report table will display the original line segment information for each line selected and the new optimised segment information for each. At the bottom of the report will be displayed the number of lines operated on and the total number of segments removed.
- Click Apply to run and keep the Simplify Linestrings command pane open.
Note: To achieve the best result, it sometimes requires the line to be processed a few times as it will continue to improve the results until nothing further can be done.