Reviewing Volume Topology

The volume topology tool is a model topology diagnostic tool for analyzing volumes, faces, and edges. In particular, the tool identifies closed volumes from the set of surfaces supplied.

The volume topology tool enables you to identify model topology issues (such as those arising from the Extract Volume operation) and it allows you to examine surfaces classified using model topology.

To run a diagnostic check using the volume topology tool:

  1. In the Global tools panel, click (Calculate and review volume topology).
    The Volume Topology Options panel appears.

  2. To calculate the topology, click Identify Volumes.
    The status of the topology calculation is represented by the icon next to the Identify Volumes option, which has four states:
    • - Results out of date
      The following actions will cause the model topology results to go out of date:
      • Modifying the mesh geometry or topology
      • Changing the model topology Initialization option
    • - Topology calculation
    • - Results up to date
    • - Calculation error
    After the topology calculation, the table is populated with results for each closed volume found in the surface.

    The results in the volume topology panel are split into three tables to list volumes, faces, and edges.

    Once the calculation is complete, the scene updates to show each volume using a color that matches the colors shown in the table ID column. To display the model ID labels in the scene when a face or edge row is selected, activate the Show Labels option in the panel.

    Surface topologies that are not part of a closed volume are listed in the table and are shown using the regular (default) gray color in the scene.

  3. In the Volumes table, select a row to display the selected volume in the scene or use the keys to cycle through the results.
    When you select a row in the Volume table, it results in two follow-on actions:
    1. The topological faces for that volume are populated in the Faces table.
    2. The graphics window updates to highlight the mesh faces corresponding to the volume.
    Similarly, selecting a row in the Faces table highlights the appropriate mesh faces in the scene and populates the Edges table with the edges and vertices for that face. If a row is selected in the Edges table, then the appropriate mesh edges are highlighted in the scene. Additionally, if the Vertex Selection option is enabled then the start and end vertices are highlighted in the scene.

  4. To select multiple rows in the tables, press and hold the <CTRL> key.
    NoteThe graphics window updates to show the selection. However, the rows in the table are highlighted to show the multiple selections.
By default, the mesh faces in the scene are colored according to the volume to which they belong. To display the results of faces in colors:
  1. In the Volume Topology panel, switch the Color Mode from Volumes to Faces.


    In Faces color mode, the appropriate mesh faces for the selected volume are colored according to the face topology instead of a single color for the volume. The ID column in the Faces table also updates to show the corresponding color for the faces displayed in the scene.
The volume topology tool allows you to use the Initialization options to define how the topology is calculated.
  1. For Initialization, you can choose from the following options:
    • Coarse—corresponds to the same topological initialization used by the Extract Volume operation and therefore makes it suitable for previewing and diagnosing problems relating to these types of surfaces. By default, the Initialization option is set to Coarse.
    • Fine—calculates the same number of volumes as the Coarse option but does not limit the number of topological faces and edges for each volume.
    If the initialization option is changed after executing a topology calculation, the model topology results go out of date although the results in the tables are still maintained. To update the results, you must click the Identify Volumes option once more so that the tool can recalculate the topology.
  2. Use the Find Selection tool to reverse look-up faces or edges highlighted in the scene and identify the volumes, faces, and edges they belong to in the topology tables.
    NoteFor edges, only mesh edges that belong to topology edges can be located by the Find Selection option.