Issues of Scale Using C o l o r. Scale Issues. What is map scale?. The scale of a map is the relationship between a unit of length on the map and a unit of length on the ground. Map Scales. Verbal scale “One cm represents 100 km” Bar scales (graphical)
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The scale of a map is the relationship between a unit of length on the map and a unit of length on the ground.
“One cm represents 100 km”
Bar scales (graphical)
Representative fraction (RF) 1:24,000
A 0.025 inch line on a1:24,000scale map represents50ft (600 in) on the ground
A 0.025 inch line on a1:200,000scale map represents almost417ft on the ground
Beware of scale statements
1:200 (“one to two hundred”) does this mean
(one inch on the map equals 200 inches on the ground)
(one inch on the map equals 200 feet on the ground)
For this course,
all scale statements will be assumed unit-to-unit
large scale vs. small scaleTo a geographer:1:2,000,000 is small scale1:200 is large scale
Scale of data plays an important role, and frequently causes problems
All spatial phenomena have scale dependent behavior/properties
Be aware of:
Data source scale
Mixing data from different source scales
Appropriateness of output scale
Data from different sources and scales can vary widely
1:100,000 scale data from USGS DLG
1:1,000,000 scale data from DCW (DMA)
1:2,000,000 scale data from USGS DLG
What can color do?
Represent or imitate reality
From Tufte 1990
Dr. Cynthia Brewer / Department of Geography / The Pennsylvania State University
Read: “Creating Feature Datasets & Vector Editing” & “Creating and Modifying Tables”
Start working on assignment #4 -- Due April 26.