Page 131 - DCAP504_Computer Graphics

Computer Graphics

basic objects related to 3-D graphics are lines and triangles. They include texture, reflectivity, RGB
values, etc.
8.3.2 Camera Coordinates

A view plane is a film plane in a camera that is positioned for a particular shot of the scene. The world
position coordinates are converted into viewing coordinates and projected into the view plane. The
view plane can be established by viewing coordinate system or View Reference Coordinates (VRC).
Specifying an Arbitrary 3-D View
We know that an object can be viewed from any direction. It is also necessary to define a view plane
based on a specified point of view. The figure 8.12 displays the view plane and the view coordinate
system.
Figure 8.12 : Viewing Coordinate System

Here the first view parameter to be considered is the View Reference Point [VRP]. It is the center of
view reference system. It is normally close to or on the surface of some object in a scene.
The second viewing parameter is the View-Plane Normal vector [VPN]. The normal vector is the
direction that is perpendicular to the view plane.

The view distance is another parameter. The normal vector is a directed line segment from view plane
to view reference point. The length of the directed line segment is called the view distance. It is
illustrated in the figure 8.14. These parameters allow the use to select the necessary object view.
Transforming World Coordinates to Viewing Coordinates
The position of objects can be described in different ways namely, the camera coordinates and the world
coordinates. The world coordinates can be converted to viewing coordinates by the following
procedure:
1. To translate view reference point to origin of world coordinate system.
2. To align the xv, yv, zv axes with the world coordinates xw, yw and zw axes, apply the rotations.

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