three-dimensional observation equipment
The design of the graphic monitor showing three-dimensional scene uses the technique of reflecting CRT image from the vibration of the flexible mirror. The operating principle of this type of system is shown in 2.16. The focal length is changed when the zoom reflector vibrates. These vibrations are synchronized with the display of objects on the CRT. Therefore, each point on the object is reflected from the mirror to the space position, corresponding to the distance from the point to the specified observation position. This allows us to walk around an object or scene and observe from different angles.
Figure 2.17 shows the Genisco spacegraph system, which uses a vibrating mirror to project three-dimensional objects into the X-cm x-cm space. This system can also show a two-dimensional "slice" that designates a cross-section of a image at different depths. These systems have been used in medical applications to analyze data from ultrasound radiography and cat scanners, and in geological applications, seismic data from terrain can be analyzed, as well as three-dimensional simulation applications for molecular systems and terrain systems.
Stereoscopic and virtual Reality system
another technique for representing three-dimensional objects is
to display a stereoscopic view . This method does not produce a true three-dimensional image, but rather gives the viewer a different view of each eye to provide a three-dimensional effect , so that the scene with depth (see figure 2.18) for a stereoscopic projection, first need to get from relative to each eye (left eye and right eye) Two views of the scene generated in the observation direction. You can obtain both views by specifying a different observation location and by a computer-generated scene, or by shooting some objects or scenes with a pair of stereoscopic cameras. When we get the left-hand view and right-eye view at the same time, the two views are synthesized into a single image, and the well senses the depth of the scene. Figure 2.19 shows the two stereoscopic projection views of a computer-generated scene. To increase the comfort of observation, the left and right areas of the scene are removed from only one eye.
One way to create a three-dimensional effect is to use a raster system to alternately display two views at different refresh intervals. Through the glasses observation screen, each lens is designed to be a high-speed alternating shutter, which can synchronously block the display of another view, figure 2.20 gives a pair of stereo glasses, which is composed of a liquid crystal shutter and the lens and screen view synchronized infrared emitter.
The stereoscopic view is also an integral part of the
virtual reality (virtual-reality) system. Users can step into the scene and interact with the environment. The hood with an optical system that generates a stereoscopic view (see Figure 2.21) can be used to connect an interactive input device to locate and manipulate objects in the scene. The sensor system in the hood tracks the observer's position so that the front and back of the object can be seen when the observer "walks in" and interacts with the display. Another way to generate a virtual environment is to use a projector to create a scene on a well-laid wall, and figure 2.22 illustrates the interaction with a virtual scene using stereo glasses and a right-handed data glove (later).
Low-cost interactive virtual reality environments can also be observed with stereo glasses and video monitors without wigs, providing a cheap virtual reality system. Figure 2.23 shows an ultrasonic tracking device with six degrees of freedom. The tracking device is placed at the top of the video display and is used to monitor the movement of the head. As a result, the viewing position of the scene can follow the change of the head position.
Computer graphics (i) video display equipment _6_ three-dimensional observation equipment
