Creating a Profile by Best Fit

2012-03-14

Product Documentation

Intermediate

Create a profile that follows the most logical path through a series of surface profiles, feature lines, COGO points, or AutoCAD 3D polylines, points, or blocks.

This tool uses a complex algorithm that you can adjust to obtain the desired results based on the type and the accuracy of the source data.

For example, when one uses COGO points as source data, the specified points are projected onto the alignment, and then sorted by station. The station on the alignment and the elevation of each point is determined; if a second path of points is specified, then the offset distance from the alignment also is determined.

Next, the algorithm calculates tangents (2) based on the sequence of the points and the specified Maximum Radius For Curve Detection setting. When a sequence of points has a radius that is greater than this setting, the points form a tangent. The apparent intersection of the tangents (3) are the points of intersection for the profile tangents. The algorithm calculates arcs or parabolas (1) by approximating the curvature by linking the sample points together with linear segments. To increase the accuracy when using either feature lines or 3D polylines, intermediate sample points may be either weeded from the original input data or created between each pair of sample points.

To create a profile by best fit

Click Home tabCreate Design panelProfile drop-downCreate Best Fit Profile .At the Command prompt, enter CreateBestFitProfile.
In the Create Best Fit Profile Dialog Box, under Input Data, specify the type of data from which to create the best fit alignment.
Next to Path 1, click .

Note
If you selected COGO Points or Surface Profile as the Input Type, you can use a drop-down list to select a point group or surface profile.
In the drawing, select the objects from which you want to create the best fit profile. Press Enter.

Note
You may only select objects that are the input type you selected in Step 2. You may not select multiple types of objects.
If you wish to create the best fit profile between two paths of objects, next to Path 2, click .

Note
If you selected Surface Profile as the Input Type, you cannot use a second path.
In the drawing, select the objects from which you want to create the best fit profile. Press Enter.
If you chose AutoCAD 3D Polylines, Surface Profile, or Feature Lines as the Input Data, click Weeding Options.
In the Best Fit Profile Weeding Options Dialog Box, specify whether to either weed extraneous vertices or insert intermediate vertices. Click OK.
Under Best Fit Options, specify the following parameters:
- Maximum Radius For Curve Detection—Specifies the largest acceptable radius of curves that are created from the input data.
  
  Note
  This value is an estimate. For best results, specify a value that is slightly greater than the largest known radius in the input data.
- Curve Type—Specifies the type of curve (either Parabola or Circular Arc) to create during the best fit regression.
Under Creation Settings, specify the following parameters:
- Profile Name
- Profile Style
- Layer
Use the Show Report check box to specify whether to show the Best Fit Profile Report Vista, which the results of the regression that was used to create the best fit profile.
Click OK.