Exercise: Create a geometric shape

In the software several methods exist to define a geometric shape:

  • Draw

  • Best shape

  • Region grow

A detailed description of the available commands and their options can be found in the help of the corresponding Extract menu.


Draw a Circle:

  • For example, go to Draw Circle and click points in the scene. Once three points are given, a circle passing through them will be appearing in the scene (three points define a circle). If you continue clicking points, the created shape will be the circle closest to the input.

  • You can constrain parameters of the shape: click on the lock radius and change its value. You will see that even if you continue clicking points the radius will be fixed to this value. In this way, you can supply additional external information about the shape to the algorithm.

Removing points

As you can add points by clicking on the scene you can also remove them with the DEL key.


A shape can also be defined in a more mathematical manner, by fixing its parameters directly. For this purpose choose the function Draw Circle and:

  • Click on the lock Center and enter the point X=10, Y=5, Z=0.

  • Click on the lock Normal and enter the vector X=0, Y=0, Z=1.

  • Click on the lock and enter 2 for the Radius.

Using tools to define parameters

You can use the available tools to fix the center (Define points) and the normal (Define normal direction) of your circle by clicking in the scene.

Once the circle is validated, you can check that the circle you created has the desired properties by selecting it and check the properties with a right click.