Working with point groups in Civil 3D

The most important thing in the civil engineering world is the most important. Learn more about working with point groups in Civil 3D.

  1. What is a point?
  2. What is Point Group?
  3. Point group dialog box
  4. Using Point Groups
  5. View a group of checkpoints

What is a point?

A point is (usually) made up of five key pieces of information, commonly referred to as a PNEZD file:

  • point number † An identifier to distinguish points.
  • North direction – coordinates of a point in the north or Y
  • East – coordinates of a point in the east or “X”
  • Z coordinate † Point height
  • Description † A short code indicating the type of your point (tree, utility pole, etc.).

Surveyors go into the field and collect all existing location information for your project as a series of points in a data collector that can be exported to a text file and then imported into Civil 3D, where the points are created as physical objects within your project. Image. Breaking it down to the simplest level, you can play with these points to draw the physical line that will become your blueprint. For example, you can draw a polyline connecting all points on the edge of a sidewalk to determine where your path is. Simple, right? Well, maybe not everything is so simple. The problem is that surveyors can accumulate tens of thousands of points on a single site, making finding the right points to connect together with your lines a compiler’s nightmare.

What is Point Group?

That’s where point groups come in. Groups of points are called filters, which group your points into manageable chunks that can be turned on or off as needed. They are very similar to layer filters in that you can only display the points you need to work with at any given time. In the previous example of the curb, it would be a lot easier if the only points we could see where the EOP images were, create a point group consisting of only those points and disable all other points. Fortunately, Civil 3D makes creating point groups a very simple process. You can create a point group from your tool space by right clicking on the point group section and selecting the NEW option. This invokes the Point Group dialog box.

Point group dialog box

This dialog is the main interface for creating your group. This gives you complete control over which dots do and don’t appear in your group, which layers they are drawn on, their display and label styles, and almost anything else you can think of. Here’s what you can do in each tab:

  • Information † Set the group name, display style and label style.
  • Point groups † You can nest other groups together to create larger groups.
  • Matching rough description † Create groups using the raw codes that the surveyors used in the data collector.
  • To turn on : Provide scores based on number, height, name, etc.
  • Exclude † Exclude points based on number, height, name, etc.
  • Search builder † Allows you to search the point data for specific points to add to a group.
  • List of points † Shows all points in your file that belong to your group.
  • Overview † Overview table of all filters in your point group.

Using Point Groups

After you create your point groups, they appear in the tool area as an ordered list. The list is very important because the order of the point groups determines which are displayed and which are not.

By default, Civil 3D already defines two point groups: All Points and No Display. By default, both groups contain every point in your file, except that in the “No Display” group, all label style and visibility settings are disabled. In an ordered list of your point groups, they appear from top to bottom. This means that if the All points group is displayed first, each point in the drawing will be displayed on the screen. If “No points” is at the top, no points will be displayed at all.

In the example above, only my top/bottom wall points are shown on the screen because the “No Display” style is directly below it, so all other points below are not shown at all.

View a group of checkpoints

You control the order and thus the appearance of point groups by right-clicking the Point groups section in the toolbox and selecting the Properties option. The dialog box that appears (above) has arrows on the right that allow you to move the selected groups up/down in the list. Just move the groups you want to work with above the “No Display” group and all the others below and say “OK” in the dialog box. Your drawing changes and you can only work with the points you need.

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