Description

Within the Projection Control frame, the mechanics of a projection, such as type and direction, are specified:

Use options in the Projection Control frame to set up type, direction and more.
Use options in the Projection Control frame to set up type, direction and more.

The Type attribute specifies the type of projection to be performed. Four different projection methods are available, each with its own advantages as described in the Types section. The naming convention for the projection methods is based loosely on analogies with coordinate system types. Each method, however, is simply a ray-surface intersection calculation. The methods differ in how the rays are cast.

 

Note: The projection type selected for the Project command is stored as an attribute of a domain so that Grid, Solve defaults to using the same Projection Method.

The Direction attribute specifies which direction the projection should take. This control depends on the relative position of the grid and database. Directional arrows are also rendered in the Display window (as can be seen in the figures in the Types section). The options for Direction are:

  • In: Sets grid points to be projected onto the first database encountered along a line starting from infinity and continuing toward the source specified.
  • Out: Sets grid points to be projected onto the first database encountered along a line starting at the source specified, going through the grid point and continuing on to infinity.

The Project Points and Project Shape radio buttons specify how grid points are handled during projection of grid entities. Both options are disabled when projecting database curves.

  • Project Points: Specifies that the grid points of a connector or domain be projected onto the target database surface. For connectors, Project Points also updates the connector shape by fitting a curve through the projected points. Note that this changes the connector distribution to a General distribution.
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    Tip: Use the Project Shape option when projecting connectors so that the connector retains its original Distribution after projection. Otherwise, if the Project Points option is used, the distribution will be changed to a General distribution.

  • Project Shape: Specifies that the shape (i.e. control points) be projected onto the target database surface instead of the grid points directly. Project Shape also ensures that connectors retain their original grid point distribution function. Project Shape is available for connectors and structured domains, but is disabled for unstructured domains.

The Interior Only attribute specifies that only the interior points be projected onto the interior of the database surface. It is recommended to check Interior Only if, for example, your domain's connectors are already database constrained (e.g., Line on DB segment types). Otherwise, your Line on DB segments will be replaced by General segments. Interior Only is disabled when the Project Shape option is selected.

The Fit Control frame is only available when the Project Shape option is selected and the entities to be projected are connectors (right). Otherwise, the frame is absent (left).

When projecting connectors, the Fit Control frame appears if the Project Shape option is selected for Projection Control. The Fit Control frame contains a single attribute, Fit Tolerance, which allows you to specify the tolerance to be used when fitting the connector's shape to the database surface.

Demonstration

Projection Controls