Page 18 - DCAP313_LAB_ON_COMPUTER_GRAPHICS

Lab on Computer Graphics

Notes being produced was indeed the one desired. When you have to wait several hours for the film
image to be developed, that is a good idea.

But there is another way to get an image with a slow computer and one that will yield an image
to the users much sooner: a plotter. Gene Said and Robert Morton, two of the founders of Cal
Comp, developed the idea in 1953, but lack of funding kept the device off the market until 1959.
The idea is simple: drive a pen on two axes. That takes a pair of stepping motors, and something
to put the pen down at the start of a line, and lift it again at the end. Software can calculate
when the pen should be stepped in either axis to draw straight lines between two points, curved
lines, or whatever.

In time, fairly sophisticated software packages were developed which isolated the users from the
plotter, and allowed them to describe the image in more human-friendly terms such as “m=1,
plot y=mx+b for x=1 to 6,” and so on. If the plotter drew a shape, the shape could be filled with
solid, dashed, or dotted lines to simulate black or greyscale. Calculating the bounds of the lines
within the shape became a part of early plotting packages. Unless one is doing ray tracing, or
something similar, the bounds for shading or colour within a surface must still be calculated
today, and the techniques still draw on these early methods.
In time, plotters had additional pens added to do drawings in colour. But the number of colours
was limited, and the drawings were still vectors.

The Odyssey, a home video game, was the first consumer computer graphics
product, developed by Ralph Baer in 1966.

Self Assessment Questions
6. Computer graphics generally means creation …………………. and manipulation of models
and images.
(a) storage (b) graphics
(c) algorithm (d) None of these.
7. Computer graphics was coined in …………………. by William Fetter.
(a) 1970 (b) 1960
(c) 1956 (d) 1958
8. The refreshing rate, called the frame rate, is normally…………………. frames per second.
(a) 50 to 80 (b) 60 to 90

(c) 60 to 80 (d) 45 to 65
9. Inkjet printers produce output by squirting ink in …………………. rows across a roll of
paper wrapped on a drum.
(a) horizontal (b) grid
(c) vertical (d) None of these.

10. Modelling coordinates are used to construct …………………. object shapes.
(a) horizontal (b) grid
(c) individual (d) visual
11. A graphics processor accepts graphics commands from the …………………. and executes
the graphics commands.
(a) CPU (b) RAM
(c) monitor (d) All of these.

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