Point Groups – How to Make Them Work for You

By Doug Aaberg • November 30th, 2017
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Thanks to Ken C. from Langan for the above creative graphic

The use of point groups is nothing new to most surveyors. For years, surveyors have been using point groups to segregate their data, usually to facilitate the drafting process. By creating a point group for all of your edge of pavement shots for example, you can isolate those points giving you a cleaner screen to work on and, in turn, speed up the drawing process. The same would go for trees, utility poles, buildings, etc.

As a digression, using Carlson’s Field to Finish program is a far superior work method than the one I just described. Field to Finish will segregate the data as much as you want but do it automatically. Furthermore, the Field to Finish Inspector allows you to isolate data by its code, negating the need to individually import points or placing them on separate layers.

The above example shows the process of isolating all EP (edge of pavement) shots using Carlson’s Field to Finish Inspector.

Using Point Groups has an advantage well beyond that of merely isolating points so you can “connect the dots” when drafting. Point Groups can be used throughout Carlson software to organize and report data, import and export data, translate, rotate or align points and add point data to TINs, lot files or roadway alignments. As a matter of fact, you will notice a “Point Group” option in a lot of Carlson Survey programs.

Here are a few worth exploring:

1. Point group manager

The Point Group Manager allows you to create and manage point groups from existing data, meaning points contained in a Carlson coordinate file. (CRD, CRDB etc.)

Point Groups can be created from a variety of methods including; by proximity, elevation range or description with wildcard options.

Once a Point Group is created, a large variety of tools are at your disposal for manipulating, editing, drafting and viewing each group.

The example above depicts drawing polylines from the Roadway Point Group.
Again, Field to Finish offers far greater flexibility, control and efficiency for drafting than does just a Point Group.

2. Importing and Exporting Points

One of the most common work flows for a surveyor is to import and export points from an ASCII file. (P,N,E,Z,D). When doing so, Carlson offers enhanced flexibility in creating and utilizing Point Groups throughout these commands.

When Importing Points, a Point Group can be assigned and created simultaneously by simply adding a name to the Point Group to Assign option. Furthermore, the points being imported and the subsequent Point Group can be further controlled by descriptions and/or proximity.

By Selecting Set, even more control over creating a point Group is possible, such as by selecting a predefined group name or using a point prefix.

For example, if an Alpha-Numeric point name was used with a prefix of LG (meaning ledge) and a prefix of 2 was entered, a point Group named LG would be created for all points matching that prefix.

Similarly, when exporting points, an existing Point Group can be selected to limit the number of points being exported, for example, the Point Group: Control Points/Monuments.


3. Creating Point Groups from Raw Field Data

One of the questions I get asked frequently refers to handling multiple days of field work. Sometimes, larger projects that require multiple days of field work also have a deadline that makes it necessary to begin drafting prior to the completion of the field work. Controlling the points entering the system on a daily basis can cause confusion.

One of the easiest ways to handle this issue is right from the Raw Field Editor.

In the Edit-Process Raw File dialog box, Select: Tools →Point Groups→Create All Point Groups.
Notice that you are allowed to create a Traverse or Sideshot Point Group as well.

4. Processing Point Groups in Field to Finish

Once a Point Group is created, you just simply select it in the Draw Field to Finish dialog box.

This is a great method of processing multiple days of field work. Create a Point Group from the Raw Field Editor and then process just that group thus saving any drafting edits previously made.

You can also create Point Groups in Field to Finish by the code name itself.

From the Field to Finish code table editor, edit any code and add the name of a Point Group to create or select an existing one.
The Point Group does not have to exist. The program will create it upon processing.

5. Using Point Groups for TIN editing.

Occasionally, it becomes necessary to add data to an existing TIN. Although creating a TIN with Carlson is quite easy, you just select any objects to be included, some TIN edits such as Swap Edge or Remove Point would have to be repeated if you recreate the TIN from scratch. In those cases, you can add point data by selecting a Point Group.

From the Triangulation Surface Manger select Add Point

At the Command Prompt, select Group and the command will open the Point Group Manager dialog box.

You will see throughout Carlson software many commands that allow the option to select a Point Group. They are very handy and help to organize your point data quite well.


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Douglas L. Aaberg, PLS

Survey Product Manager



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