Best Fit Linestring
COMMAND LICENSING AND DEFAULT MENU LOCATIONS
- 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.
COMMAND DESCRIPTION
Creates best-fit horizontal and / or vertical alignment geometry from a selected 3D linestring. This 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 HISTORY
Update Information
November 29, 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.
VIDEO DEMONSTRATION
The following video shows how to utilize the Best Fit Linestring command:
SETUP AND CONFIGURATION
Command Interface Description
The Best Fit Linestring command dialog looks as follows:
Linestring:
Select the source Linestring for the computation of the alignment. Typically, this Linestring will have been surveyed at regular intervals along the centerline of the road / haul road / access road and provides an accurate representation of the current road surface at the centerline.
Name:
Define the name for the new linestring.
Layer:
Select the layer for the best-fit linestring that will be created. You can create a new layer and layer group by clicking the 
button, and you can apply layer filters using the 
button.
Tolerance:
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).
EXECUTE
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.
Results:
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, e.g., 0.35, is a worse fit of the data.
COMMAND TIPS
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.
HEADER BAR COMMANDS
In the Header Bar of the command, you will find command icons that link you to other commands that you may need access to while using this command. In this command, the following commands are linked:
- Help - this document access
- RPS Settings
- Takeoff Lines
- Smart Edit
- Adjust Linestring Elevation
- Convert to Linestring
- Create Alignment
- Create Horizontal Alignment Labels
- Linestring by Station
- Profile Viewer
APPLY BUTTON
When you tap Apply, the alignment will be computed and drawn in the graphics view, and the command will prepare itself for another selection set and another process execution. If you do not want to make a second selection and repeat the process, tap Close to finish the process.
CLOSE BUTTON
Closes the command without further execution.
USE CASE VIDEOS
The following videos show the use of the Best Fit Linestring command in a workflow 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 Reply below.