Computer graphics for the graphics, design and engineering industries doesn't stop with the graphic. Its goal is to depict a real world condition. In
tomorrows fast paced global economy, rapid and accurate communication of
information will be critical for societies efficient operation. Computer
imaging can play a major role in assisting the designer to accurately
communicate to others through a photorealistic rendering presentation. Using state-of-the-art computer-aided video imaging technology you can increase your communication effectiveness and enhance profitability.
Video imaging is a cost effective and integrated component of the electronic
design process. Video image samples of real world materials bring a sense of realism to C.A.D./C.A.E. ray traced renderings. Further expanding the
powerful functions of C.A.D./C.A.E. and desktop publishing, video imaging
completes this trio, creating exceptional presentation graphics. Because of
it's rapid visualization capabilities, video imaging is unparalleled for
previewing the design, analysis and pre-development processes. The high
degree of photorealism generated by computer imaging gives the concrete image of the finished product. With the use of video imaging you can also
facilitate planning review and get pre-approval from regulatory agencies while the project is only in its planning stage! Studies coupled with experience have demonstrated this fact. Presentations that are prepared on sketch paper and colored with markers give the impression of a design in the preliminary phase of analysis, one that is subject to further input and revisions.
Airbrushed renderings will encounter a lesser level of critique by the client
or review board, yet are not fully convincing, still appearing to float
somewhere between the imagination of the designer and the final concept.
Overcoming these perceptual pitfalls leaves the visual communication abilities of computer imaging unparalleled. Renderings that are photorealistically accurate leave very little to the imagination, hence most people are not likely to intervene during reviews as they would with presentations that have the appearance of not being as polished. As we evolve into a global marketplace, the need for concepts to be universally understood poses an even greater demand for photorealism in business graphics, scientific visualization or architectural and engineering rendering presentations. Using photorealistic images, cultural, language and perceptual barriers dissolve under the dynamic power of this sophisticated presentation medium.
Meeting this challange requires an ever greater awareness of which software
technology will best facilitate the design proposal's accurate communication. Given the full range of marketing capabilities, from presentation slides, videos and posters to brochures and printed reports, determining which technology provides the best solution requires an understanding of the nature of available presentation media.
ASSESS THE GRAPHICS OBJECTIVE
Before determining the best available graphic means, one must assess the
objective of what the graphic communication is to convey. The method and
manner of presentation type needed directly influences which technology will offer the the proper solution. Presentation types include slides, hardcopy output and videotape.
Slide presentations are perhaps the most popular communication tool. When
using slides to make an architectural presentation, the importance of
resolution becomes a primary consideration. Slides are easily transported and compact, allowing for detailed analysis of their content. If the objective is to convey materials, textures and details accurately, a slide show is perhaps the most cost effective. Choosing this medium requires careful attention to the pixel resolution of the initial image. Even though many slide output devices offer interpolation routines to increase a low resolution image in an attempt to reduce the "jaggies", if you are working at NTSC resolutions, all you have done in effect, is create a blow-up of this low resolution image.
Most real world materials require 30 x 30 pixels per square foot of surface
area, if a satifactory level of descriptive detail in the material is to be
retained by the image. Not having the needed level of information, materials
begin to appear surrealistic, not photorealistic. If this square foot area is
to be shown in the middle to background areas of the perspective, current NTSC resolutions reduce the available pixel count per square foot to approximately ten pixels.
Hardcopy output, whether prints or posters, is governed by the same resolution considerations just stated. Hardcopy output, though more cumbersome, may be posted and viewed at any time. This is appropriate for longer term displays and presentations. Hardcopy output is more costly than slides to produce, but doesn't require investing in a slide projector and allows the recipient of the proposal to view the concept at any time. Some detail is lost by this method of output. Photographic prints are the best, but still suffer some loss. Thermal, ink and related devices are lower cost and oftentimes lack a sufficient range of color or D.P.I. (dots per inch) to be as convincing as a color slide or a color print.
If the purpose of the presentation is to communicate an idea, choose the most polished appearance. Integrating computer generated renderings into Desktop Publishing becomes an issue of image file format compatibility between the technology and Desktop Publishing software. In addition to textural resolution, contrast is the other key, as all color becomes halftone. Here again the same rules apply, detail and crispness of the printed image. For best results, output postscript at 2400 d.p.i., using metal plates for
printing (or hand out all originals). Photocopies of images rarely convey
information accurately unless accompanied by a color print or slide, using the black and white halftone only for reference.
Full color range and detailed material resolution are most crucial when it
comes to high resolution color separations. Current software technology is
put to task when preparing pre-press imaging of projects that are headed for
mass color printing.
Videotape animation is an opposite approach than those discussed above.
To see the design from more than one point-of-view, the computer can be
programmed to cause the optical illusion of motion by moving graphical objects incrementally across the screen at a rate of 15 or more positions per second. The appearance of motion is assisted by the persistence of the eye and the brain filling in what it expects to see. All recorded motion, from movies to videotape, is in fact a sequence of individual pictures recorded one-at-a-time onto a film or magnetic medium. As the medium is played back at normal speeds over 15 times per second, the eye thinks that it perceives motion. When the film or videotape is played back at 24 to 30 frames per second, we see smooth animated motion.
Limitation soon arise with the size of the computer memory and the speed of
its processor. As the resolution of the picture increases, the size of the
computer files goes up; as the number of displayed colors increases, the file
sizes increase too. All these changes to the file sizes, means that the
motion sequence slows down on the screen. Pretty soon you notice the
"jerkiness" and hesitations of the motion more and more. By the time the
visual quality of each graphic is achieved, the animation has slowed down to a slide show.
If smooth, fluid motion is desired then the computer must transfer each
individual graphic to another medium one-at-a-time until the whole sequence has been recorded. Keeping in mind that each second of animation is 30 pictures, and that 30 minutes is 54,000 recordings, this process can take hours or days. The payoff is what you would expect to see however, that is smooth motion at 30 frames per second. The computer builds each graphic into a frame buffer, then the whole graphic is encoded into electronic signals that the recorder can handle, then the recorder is commanded by the computer to advance to the next frame and actually make the record magnetically or optically. A tape recorder can only make the recording when it is at speed, therefore, the tape recorder is continually stopping, backing up, getting up to speed, recording one frame and stopping again, over and over again. Industrial quality edit decks are especially designed to take this beating for thousands of cycles, whereas consumer models would soon fall into disrepair. Edit decks are also designed to be frame accurate, as each graphic must be exactly recorded into its designated place. If the recorder is not frame accurate, the graphics will be misplaced and the resulting motion will be jerky or contorted.
Once the animation sequence is accurately recorded, this is most likely going
to be combined with other pre-recorded materials. The animation sequence is once more controlled frame accurately to enable other recorded frames to be exactly aligned side-by-side to achieve the smoothness of the transition from scene to scene. This process is called match-frame editing, and the recorders are incremented by frame accurate edit controllers. In many cases the edit controller and the animation controller can share the same equipment, thereby reducing costs.
Presentation of the final work can be either be sequential, or interactive
segments commanded by a user. In many cases the presentation can be
multimedia in nature, where multiple sources can be switched by computer onto a single screen, and often be combined with sound to complete the
communication. Multimedia controllers can orchestrate 30 or more machines at the same time, plus turn down the lights and close the drapes.
Whatever the intended use, all the creation and editing can be accomplished
at your desktop with affordable equipment, complemented by a personal
computer. The entire process is under your control, and is extrememly
cost effective.
PHOTOREALISM MEANS CONTEXT
When generating photorealistic imagery, interfacing with the background
environment is very important. As nothing exists in a vacuum, so must the
designer's image have environmental context if it is to achieve accuracy of
communication. As all perception is relative to its environment, how an
object, building, structure or open space is viewed is governed by its
surroundings. If the surrounding buildings are white or beige for example,
they will have a significant influence on the desirability of the proposed
building's color. The rendering must be colored exactly and accurately
demonstrate the view of adjoining structures and landscaping.
FINDING THE APPROPRIATE SOLUTIONS
How the chosen technology handles the design principles of perspective,
shading, color and texture representation, environmental context and the
media chosen to convey the image will significantly impact its degree of
photorealism, hence, believability. A multitude of computer graphics
technology is presently or being made available soon that, to one degree or
another, is suitable for presentation development.
Environmental design, of course, occurs in three dimensions. Generating a
spatial geometry is the first step required toward development of a
photorealistic presentation. Doing this is readily accomplished by 3-D CAD
drawing packages, the most popular being AutoCAD (Autodesk, Inc.). Running
on most platforms, a fairly detailed geometry may be evaluated. This geometry is a skeletal outline with colors ranging up to 256. As only designers can relate to these wireframe models, this is only the first step toward the creation of photorealistic renderings. Most people need a picture!
The following steps are a mix of mapping textures to this wireframe:
1.) Blending this texture mapped wireframe harmoniously into its environmental context.
2.) The texture mapped wireframe must be properly aligned to the existing
perspective vanishing points.
3.) Finally, shading the texture mapped wireframe model with the surrounding sun angle. This assemblage must then be frozen for high resolution stills or animated for viewing from multiple directions. Of course, all of this is not possible at once, at least for now. This creates some performance trade-offs that should be evaluated when making the decision as to the appropriate communication medium.
The software technology falls into two broad camps. One is raster paint and
the other 3-D vector geometry. The main difference is how the image
information is handled. Underlying both of these is the display resolutions
of the graphics adapter and output devices. The importance here is the
accuracy and level of detail the image must communicate. Knowing the
presentation objective helps to guide this mix. A versatile option is to use
rendering software. This software is able to map full color textures to the
wireframe geometry while having the ability to manipulate the texture mapped geometry in space. Mapping textures must be done carefully, insuring that the proper scale relationships are adhered to for the materials being represented.
If, for example, the plane represents an eight foot high brick wall, the brick
texture must be scaled so that the representative number of rows of brick are placed into this area. The material texture, if properly developed, will have been sampled from real world conditions with bright sunlight highlighting the bricks relief. Because the shading ability of the software will treat the wall plane as flat, the only method for displaying textural relief of this plane (read photorealism) is to have the original sample represent this condition as do ImageCELs ¿. Having completed this step, we may view the textured geometry from many angles. The trade-offs are that the image exists in a vacuum, you can't show how the surrounding buildings look if you were to move around the scene. Also, resolutions are limited by the display adapter, meaning that NTSC display adapters are only capable of viewing scenes of indoor spaces and close-ups of fascades with any degree of photorealism.
Raster imaging is an image created with many points of color, giving the mind the illusion of a scene, as demonstrated by our Impressionist forebearers. Of course, giving the mind an image with detailed information requires that lots of pixels make up the illusion. This objective is best handled by assembling the image in a range between 2K x 2K and 4K x 4K pixels. Given this need for high resolution, current technology is limited to a static two-dimensional surface.
Another approach involves shading the wireframe. Using the appropriate
graphic display adapters from and the appropriate drivers, continuous tone
perspectives ideal for mapping textures at high resolutions may be developed. The key to using this approach is making sure that the camera and target coordinates are identical for both the shaded model and the picture taken of the site. This is vitally important for the seamless integration of the model and background. Having completed this task, the image may be interpolated to the higher resolutions.
The ability to assemble both raster and vector geometries into a
photocomposition at high resolutions makes it useful for post production and
pre-press. Even though these images must be built-up by hand, the framework of a shaded 3-D geometry helps define the perspective necessary to properly complete a photorealistic raster image.
Because the image at this point is continuous tone, gradations need to be
mapped over the shaded image to give the impression of planes receding away from the viewer.
The final step involves overlaying the textures of the selected materials to
these planar surfaces. Using ImageCELS ¿ Libraries of real world objects
and textures, photorealistic elements combine to create the finished high
resolution rendering.
Numerous software advances are on the horizon which promise to enhance the ability to generate photorealistic images. Because designers are rarely
satisfied with looking at a static picture (they like to see their creations
come alive), animated 3-D Vector Modeling will be making great strides in the coming decade.
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