Best Fit Linestring Command

D_BestFitLineString_600ppi   Best Fit Linestring

Command Licensing and Default Menu Location

  • The Best Fit Linestring command is part of the RPS Modeling Toolbox
  • The command is located on the Modeling macros menu ribbon
  • The command is located in the Corridor menu group

Latest Updates

November 29th 2022
Added a layer control for the best fit linestring that gets created using the command.
Improved some error checking in the command to improve performance.

Command Description

Creates a best fit horizontal and or vertical alignment geometry to a selected 3D linestring. Can be used to define a new alignment and profile for a pavement or regrading surface based on surveyed data along the centerline for example.

Command Interface Description

The Best Fit Linestring command dialog looks as follows

Select the source Linestring for the computation of the alignment. Typically this Linestring will have been surveyed at regular intervals along the center line of the road / haul road / access road and provides an accurate representation of the current road surface at the center line.

Define the name for the new linestring

Select the layer for the best fit linestring that will be created. You can create a new layer and layer group by clicking the image button and you can apply layer filters using the image button

Input the computation tolerance that you wish to achieve for the best fit alignment. If you enter a very high tolerance, the best fit alignment will closely match the source linestring and will need to incorporate many horizontal and vertical elements in order to do so. If you enter a looser tolerance, then the alignment elements can be longer and the best fit alignment will likely be smoother but will deviate more from the source Linestring. Typically give the tool some room to work e.g. 0.1’ to 0.2’ or up to 0.5’ (between 2 and 10 cm).

Min segment length:
Input the desired Minimum Segment Length for the computed best fit alignment. If you set this number large then the elements will be smoother but will likely deviate more from the source linestring. If you set this small then you will get many more alignment elements in the resulting line. Typically use a value at least 2 to 3 times the average point spacing on the source linestring as a guide. Typically if your measured line has points every 10’ then use a value of 20 to 25’ here.

Max Segment Length:
This value is less important unless you specifically want to constrain the Maximum Length of a segment in order to drive the computational behavior of the tool. In most cases, if a single Best Fit Line segment can fit the whole source linestring within the tolerance specified then that would be a good result. Typically enter a value close to the length of the source linestring or higher e.g. 10000, or a reasonable length of segment as typically found on road projects e.g. 500’

Calculation mode:

  • Only Horizontal - Choose this mode if you only want a Horizontal Alignment computed
  • Only Vertical - Choose this mode if you only want a Vertical Alignment computed
  • Both Horiz and Vertical - Choose this mode if you want a full 3D alignment computed

At the end of the process, the tool provides an estimate of the “fit” of the computed alignment to the source linestring. A low number e.g. 0.05 is a good fit, a high number 0.35 is a worse fit of the data

Operation notes:
It is recommended that you run the same command several times with a variety of settings to generate different alternatives in order to derive the best solution. Different combinations of source data may require different settings in order to compute the optimal result.

When you tap apply, the alignment will be computed and drawn in the graphics view and the command will ready itself for another selection set and repeat process execution. If you do not want to make a second selection and repeat the process tap Close to finish the process.

Closes the command without further execution.

Video Demonstration

The following video shows how to utilize the Best Fit Linestring command

Use Case Videos

The following videos show the use of the Best Fit Linestring command in a work process context

Feedback and Enhancement Requests

If you would like to provide feedback on the use of the Best Fit Linestring command or to request enhancements or improvements to the command please Click Here

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