Camera View Projection
The Define Camera tool supports four view projections:
- Parallel — default (no perspective).
- Three Point — for conventional perspectives.
- Two Point — for architectural use where vertical edges are required to be kept vertical.
- One Point — for dimensionally correct sectional perspectives.
Choosing any of these options, in the Define Camera settings window, changes the projection in the camera view accordingly. Similarly, the view cone updates with the new viewing parameters. You may change the view projection at any time.
The standard viewing projection is parallel. This projection is most commonly used during the design process. Here, the view cone is rectangular in shape.
Three Point Projection
Three point projection is the most natural projection, and is used for conventional images. In this projection, the image plane is normal to the direction of the view, as in a conventional camera.
Two Point Projection
Working in a similar manner to a bellows camera, the two point projection is most commonly used for architectural renderings where vertical edges are required to be displayed as vertical, even in the perspective views.
Here, the image plane is kept vertical, but oriented in the horizontal direction of the view. In this way, you get perspective while keeping any vertical edges completely vertical in the image.
One Point Projection
With one point projection, the orientation of the image plane is completely independent of the view direction. To cater for this, an extra handle, normal to the image plane, is added to the view cone. This handle controls the direction of the image plane.
An advantage of one point projection is that of dimensional correctness. That is, if you have the image plane parallel to a plane of the model, then the dimensions of the model in that plane are to scale. This lets you create an image that has both depth and dimensional correctness in the selected plane.
Once the camera and target locations have been set, you then use the plane handle to manipulate the image plane to be parallel to the required face. This can be done graphically, or via settings in the Camera Orientation settings fields.