30 Questions
What device can be generalized to include any device that returns character codes?
Keyboard
How many bytes does ASCII assign to each character?
One
What do encoders inside the mouse and trackball devices measure?
Motion
What allows for a much richer set of supported characters in Internet applications compared to ASCII?
Multiple bytes for each character
Which type of detectors are used in some variants of devices to measure motion?
Optical detectors
Why are small trackballs popular with portable computers?
They can be incorporated directly into the keyboard
What kind of software do users use for editing lists of information for a renderer?
Interactive modeling software
What model is commonly used to produce images of objects in real time?
Synthetic-camera model
Where are the models and their properties placed for rendering?
Scene graph
What is examined in Chapter 10 of the text?
Scene graphs
What was the early display technology based on in early graphics systems?
Calligraphic CRT display
What type of architecture was commonly used in early graphics systems?
Von Neumann architecture
What is the essence of image formation?
Combining the specification of the object with the specification of the viewer to produce a two-dimensional image.
What is missing in the description of image formation?
The mention of light sources.
Why would objects be dark without light sources?
Because there would be no illumination, making them not visible in images.
What determines how much light enters the camera in a physical imaging system?
The details of the interaction between light and the surfaces of the object.
What is light considered as?
A form of electromagnetic radiation.
How many dimensions is the image that is found on the film plane?
Two-dimensional.
What does the moveto function do in the graphics system described?
Moves the pen to the specified location on the paper without leaving a mark.
Explain the function of lineto in the graphics system.
Moves the pen to a new location and draws a line from the old to the new pen location.
What is the purpose of initialization and termination procedures in the graphics system?
They help set up and clean up the drawing environment.
How can you alter the drawing color or line thickness in the graphics system?
By changing pens.
What is an application where systems built on the graphics model described work well?
Page layout in the printing industry.
What is an example of a standard language in the printing industry that extends the described graphics ideas?
PostScript pagedescription language.
What can the user program do if there is an event in the queue?
The program can look at the event's type and then decide what to do.
What is associated with a specific type of event?
A function called a callback.
Why is the event-mode model approach used?
Because it is the one currently used with the major window systems and has proved effective in client-server environments.
What is the traditional pedagogical approach to teaching computer graphics?
Starting with how to construct raster images of simple two-dimensional geometric entities.
What kind of images can be created using the traditional pedagogical approach?
Simple images of simple objects.
What is included in the discussion of two- and three-dimensional mathematical objects in the computer?
How to image them with the set of two-dimensional rasterized primitives.
Study Notes
Interactive Modeling Software
- For complex scenes, users use interactive modeling software to edit lists of information for a renderer.
- Most modelers use the synthetic-camera model to produce images in real-time.
Graphics Architectures
- Early graphics systems used general-purpose computers with the standard von Neumann architecture.
- These computers have a single processing unit that processes a single instruction at a time.
Input Devices
- The keyboard device returns character codes using the American Standard Code for Information Interchange (ASCII).
- The mouse and trackball are similar in use and construction, converting motion to signals sent back to the computer.
- There are many variants of these devices, some using optical detectors rather than mechanical detectors to measure motion.
Graphics Systems and Models
- A scene graph is a data structure that contains models, including geometric objects, lights, cameras, and material properties.
- The scene graph is passed to a renderer or game engine.
Image Formation
- Image formation is the process of combining the specification of an object with the specification of a viewer to produce a two-dimensional image.
- Light is a form of electromagnetic radiation that interacts with surfaces of objects and enters the camera through the lens.
Programmer’s Interface
- A simple graphics system can be described with two drawing functions: moveto(x, y) and lineto(x, y).
- The moveto function moves the pen to a location without leaving a mark, while the lineto function moves the pen to a location and draws a line from the old to the new location.
Test your knowledge on ASCII character codes and their representation in computer devices. Understand the assignment of single unsigned bytes to characters and explore the importance of these codes in computing applications.
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