Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
1997-10-02
2001-07-31
Zimmerman, Mark (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
C345S426000
Reexamination Certificate
active
06268863
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to image generation and more particularly to a method of simulating a photographic camera for rendering two-dimensional images.
BACKGROUND OF THE INVENTION
Computer graphics is a field that is best described as a merger of art and science. Many popular graphics tools require a significant amount of training in order to make use of features provided. Popular areas for computer graphics include desktop publishing, animation, and photography.
Not unlike painting, drawing, photography, machining, sculpture, etc., individuals develop niches within desktop publishing. These skills are very significant for high end professional publishing efforts. High end efforts often require a team of specialized individuals each performing a subset of tasks required to produce the end result.
In lower end desktop publishing efforts, a series of less sophisticated tools that provide fewer, but easier to use features are used. It is, therefore, highly desirable to provide ease of use for applications addressing the desktop publishing market. It is also desirable to provide advanced features in an easy to understand and learn or “intuitive” fashion.
In animation, a similar problem exists. Often computer animation is performed using a team of artists and a team of computer operators or computer animation specialists to achieve the desired results. These results often require significant duplication of effort and significant management skill to maintain communication between the groups. An intuitive feature full animation tool obviates the need for a team of computer operators by allowing the artists to act both as artists and as computer operators.
In photography, digital photography is replacing the well known system of capturing photographs, processing the negatives, printing the photographs, and scanning them into a computer for inclusion in computer graphics. Unfortunately, many features available in cameras, are not available in digital cameras. For the artistic community, this still presents significant advantages to using non-digital cameras.
Unfortunately, the ease of use of an application is very difficult to design. Firstly, most designers are scientists and have little appreciation for the user of a system. Secondly, computers are not designed to provide the same instantaneous visual and tactile feedback that is the result of art. Thirdly, many complex graphics applications are designed for specific niche markets and not intended for the desktop publishing market.
Digital cameras are becoming a common tool in photography and graphic arts. A common form of digital camera replaces its non-digital equivalent. A camera, often provided with a wide angle lens and a digital auto-focus circuit allows for point and shoot photography. Most often objects at a central location within an image appear in focus. Some digital cameras are provided with multiple auto-focus settings allowing objects at different locations within an image to be the focus point for the image.
In order to produce an image of an object for use in desktop publishing, the object is set up in a display and photographed with a digital camera. When the object is unavailable, an image of the object is drawn in at a later time or a mock up of the object is photographed. Once the image is captured, the photographer can rearrange the objects for further photographing when desirable or, when pleased with the captured image, can move on the another project. Unfortunately, a desktop publisher is incapable of easily modifying the captured image.
In practice, a photographer captures an image and sends it to a desktop publisher. In today's global market place, the photographer and the desktop publisher may be in different cities and transmit information electronically or by courier. Also, some objects such as museum pieces are geographically restricted so a photographer local to the object is necessary. When an image is unacceptable due to layout considerations or management concerns, the problems are conveyed to the photographer who captures new images and sends them to the desktop publisher again. Unfortunately, it is difficult for the photographer to see exactly what the desktop publisher has in mind; this process may repeat numerous times. When a courier is used for sending photographs, the process may take weeks or longer. During that period, the photographer's studio must remain occupied, or the photographer must expend significant amounts of time setting up the studio prior to each photo shoot for the desktop publisher. Because of this, even small changes are costly.
Capturing three-dimensional digital information regarding object geometry and colour is known as described, for example, “Using images to estimate reflectance functions” by K. F. Karner (Proceedings of WSCG '96: Fourth International Conference in Central Europe on Computer Graphics and Visualization 96; 1996; 2 vol. Iii+427 pp.p.133-40 vol. 1) and “BRDF reference standards for the infrared” by Oppenheim, Turner and Wolfe (Infrared-Physics-&-Technology; vol. 35, no. 7; Decemeber 1994; p. 873-9) among other references. For example, a range sensor and an object are moved relatively one to the other to capture range images of each external surface of the object. The object (geometry is then formed by a composite of all images and accurately reflects the geometry of the object captured. Colour information is currently captured using normal reflectance which determines a true colour of an object from an angle at a normal to the surface of the object. For most objects, this is sufficient colour information to accurately display an image of the object on a computer screen. The information is stored with reference to positional information in the form of colour and location, pattern and area, etc. The object of colour capture is to allow a more complete reconstruction of an image of the object.
Thin film effects as are commonly seen in soap bubbles are not easily modeled using normal reflectance. For these, bi-directional reflectance distribution functions (BRDF) are captured. Methods of capturing BRDF are known and current work in that area is improving quality, speed and ease with which BRDF are captured. Using BRDI information, accurate reconstructions of images of modeled objects are possible from virtually any angle. Of course, a captured model is capable of augmentation to improve colour or geometric information as technology improves.
Currently, these three-dimensional object models are viewed with software viewers on a computer display. The viewers render the objects in a known fashion as described below.
Thus, in an attempt to overcome these and other limitations of known prior art devices, it is an object of this invention to provide a method of simulating a camera with a computer.
SUMMARY OF THE INVENTION
In accordance with the invention, there is provided a method of simulating the functionality of a photographic camera having a lens, an imaging plane and parameter values effecting imaging comprising the steps of:
a) locating within a virtual space a virtual three-dimensional object to be imaged;
b) providing parameter values from the parameter values; and,
c) rendering a two-dimensional digital image of the virtual three-dimensional object by simulating light passing through the lens and onto the imaging plane of the photographic camera having parameter values substantially the same as the provided parameter values.
In accordance with the invention, there is provided a method of simulating the functionality of a photographic camera having a lens, an imaging plane and parameter values effecting imaging comprising the steps of.
a) locating within a virtual space a virtual three-dimensional object to be imaged;
b) locating within a virtual space a virtual light source;
c) providing a parameter value indicative of a desired depth of field; and,
d) rendering a two-dimensional digital image of the virtual three-dimensional object and having the desired depth of field by simulating light from the virt
Freedman & Associates
National Research Council Canada
Padmanabhan Mano
Zimmerman Mark
LandOfFree
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