Characteristics and Examples of Spatial Data - Introducing Geographic Information Systems with ArcGIS - page 97

FIGURE 2-3 An orthophotoquad image of a portion of northwestern Michigan
airspace in three dimensions.” Anyone who has worked planning or management related to the land
knows that God also puts a lot of surface area in two dimensions. Thus, any spatial database used for
land and resource considerations will either (a) not cover much area, (b) not include much detail, or (c) be
very big. Very big databases, regardless of their simplicity, are expensive to build and maintain.
Spatial data in general use up a lot of computer memory and disk space. For example, Figure 2-3 is an
orthophoto image of a part of northern Michigan (around Frankfort and Pilgrim) and Lake Michigan. 3
It represents an area of about 30 square miles.
The image consists of square (picture elements, or pixels) that are 1 meter on a side and can be displayed
white, black, and 254 shades of gray. The file underlying the image, represented in the most basic form,
binary, looks like this:
11111110101010101111111101000000101010000010100000000000010101011110101011001110001
01010100010011101010001000001000010000111101000100100101001000110010001001110010111
11110101010101111111101000000101010000010100000000000010101011110101011001110001010
10100010011101010001000001000041000011110100010010010100100011001000100111001011111
11010101010111111110100000010101000001010000000000001010101111010101100111000101010
10001001110101000100000100001000011110100010010010100100011001000100111001011111110
10000001010100000101000000000000101010111101010110011100010101000100111010100010000
3 All Figures in this textbook are on the DVD that accompanies the topic. They are in the folder Color_Figures. The size,
and in some cases, color of these figures may provide you with additional insight.