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Table 1. Comparison of Early Systems<br />

——————————————————<br />

ORRHIS<br />

The Oak Ridge Modeling<br />

Information System<br />

PIOS<br />

The Polygon<br />

Information Overlay<br />

System<br />

LOIR<br />

The New York Land Use<br />

and Natural Resource<br />

Information System<br />

CGIS<br />

The Canada Geographic<br />

Information System<br />

^S. SYSTBt<br />

PROCESS ^X.<br />

1972<br />

1971<br />

MLMIS<br />

The Minnesota Land<br />

Management Information<br />

System<br />

————————————————————<br />

1969<br />

1967<br />

1964<br />

pate Initiated<br />

flying spot scanner<br />

small grid<br />

manual<br />

manual ! digitizer<br />

large grid medium grid<br />

polygon<br />

Basic Technology<br />

Data Capture<br />

drum scanner<br />

Encoding fine polygon<br />

.polygon, linear, and<br />

point data from source<br />

map are transferred to<br />

a mylar, category by<br />

category, and <strong>the</strong> mylar<br />

is photographed each<br />

step<br />

scan to detect darkened<br />

areas, each darkening<br />

representing a category<br />

Graphic Data<br />

Pre-processing<br />

polygons and classi<br />

fications drawn on<br />

stable base mylar<br />

none<br />

air photo interpret.<br />

compile on quad maps<br />

scribe polygon boundaries.<br />

number polygons and mark<br />

centers<br />

U)<br />

K)<br />

digitize polygon<br />

boundaries<br />

mark sense card<br />

manual coding to<br />

OTM (1 km2 ) grid and<br />

keypunch<br />

scan for presence of line<br />

segment, digitize polygon<br />

centers<br />

Data Capture<br />

Techniques<br />

none<br />

none<br />

vectorization of bits<br />

indicating presence of<br />

lines or boundaries<br />

between areas<br />

vector; polygon, distancedirection<br />

notation<br />

Sncoded Data<br />

Data Deduction<br />

reduction of sum<br />

cells to 3.75 second<br />

or larger grids<br />

sliver and gap<br />

removal<br />

geodetic hierarchal<br />

grid, predominant<br />

or percentage<br />

quick look plots<br />

vector, polygon chain<br />

of x, y coordinates<br />

grid, predominant use<br />

grid, percentages of<br />

each grid in par<br />

ticular land uses<br />

Mode<br />

delete, change,<br />

rotate, shift<br />

polygons<br />

redundant interpreta<br />

tion, machine echo<br />

plot of coding<br />

sample field check<br />

gap and spike removal,<br />

edge matching<br />

Editing

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