Orthogonal and Perspective view modes

3D objects in orthogonal projection sometimes look as if they were 2D. Perspective projection mode makes presentations look more realistic.

It is possible to switch between two modes using VTK viewer toolbar buttons:

Perspective mode button

Orthogonal mode button

For example, look at the tube shape in both views.

Shape in perspective mode

Shape in orthogonal mode

Further than that, it is possible to exercise full control of the presentation of a 3D scene by modification of camera attributes.

To understand how the scene is built, see this picture.

• Camera position defines the location of the camera.
• Focal point defines the point where the camera is aimed.
• View up defines the camera orientation.

To change camera attributes, click Change View Parameters button in the VTK viewer toolbar.

The following dialog will appear:

• Focal point - can be set in the center of the bounding box of all displayed objects, or in the origin of coordinates, or defined by the user.
• Camera position - can be defined by the absolute coordinates or by the coordinates relative to the focal point.
• View up defines the vector of camera orientation.
• Zooming in Orthogonal mode is defined by Scale factor, in Perspective mode is defined by View angle.