cs 128/es 228 - lecture 7a1 digital map sources ii

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CS 128/ES 228 - Lecture 7a 1

Digital Map Sources II

CS 128/ES 228 - Lecture 7a 2

The first rule of building a GIS

Try to use somebody else’s data before you even think of

generating your own

CS 128/ES 228 - Lecture 7a 3

4. Vector data formats

CS 128/ES 228 - Lecture 7a 4

Digital line graphs (DLGs) Scales 1:24,000 1:100,000 1:2x106

Full topological data structure (nodes, lines, areas + adjacency information)

Layers: 9 feature classes, street & address information, elevations

Projection: UTM (large & medium scale), Albers Conical Equal Area (small scale)

CS 128/ES 228 - Lecture 7a 5

DLG Topology

Lines = ordered sets of points with a node at each end. They can’t cross themselves or other lines

Nodes = endpoints of lines(points are degenerate lines that start and end at the same node!)

Areas = continuous regions bounded by lines. Not true polygons – areas are constructed from bounding lines and an area identifier

CS 128/ES 228 - Lecture 7a 6

Area hybrid topology

Network & area info in same file

All closed line circuits define areas – but not all areas havecartographicidentities

Hydrology ex: lakes and streams

CS 128/ES 228 - Lecture 7a 7

Tributaries are single lines

Two Mile Creek near campus

CS 128/ES 228 - Lecture 7a 8

Rivers are made of 2 lines

Allegheny River near campus

CS 128/ES 228 - Lecture 7a 9

Major feature classes

CS 128/ES 228 - Lecture 7a 10

Major attribute codes

CS 128/ES 228 - Lecture 7a 11

Minor attribute codes

CS 128/ES 228 - Lecture 7a 12

Olean DLG: all layers

CS 128/ES 228 - Lecture 7a 13

Olean DLG: roads (4 layers)

CS 128/ES 228 - Lecture 7a 14

Olean DLG: add water features

CS 128/ES 228 - Lecture 7a 15

Olean DLG: add railroads

CS 128/ES 228 - Lecture 7a 16

Olean DLG: add contours

CS 128/ES 228 - Lecture 7a 17

5. TIGER maps

U. S. Census Bureau’s DLGformat

Include county,census tract, &census block

De facto standard/source for most commercial geocoding and trip planning software

Topologically Integrated Geographic Encoding & Referencing system

CS 128/ES 228 - Lecture 7a 18

The TIGER map browser

CS 128/ES 228 - Lecture 7a 19

Center on a familiar point…

CS 128/ES 228 - Lecture 7a 20

TIGER for Allegany NY

CS 128/ES 228 - Lecture 7a 21

TIGER files in ArcMap

CS 128/ES 228 - Lecture 7a 22

Census IDs

CS 128/ES 228 - Lecture 7a 23

Census Bureau databases

American Factfinder

Reports in table or map form

Joins or relates?

CS 128/ES 228 - Lecture 7a 24

NYS Income, by county

CS 128/ES 228 - Lecture 7a 25

Resolution to the census tract

CS 128/ES 228 - Lecture 7a 26

Local demographic stats

CS 128/ES 228 - Lecture 7a 27

Local housing costs

CS 128/ES 228 - Lecture 7a 28

Thematic Census maps

CS 128/ES 228 - Lecture 7a 29

Themes may be reclassified

CS 128/ES 228 - Lecture 7a 30

Equal frequency classification

CS 128/ES 228 - Lecture 7a 31

Summary: digital data sources

Digital raster graphs(DRGs)

Digital line graphs(DLGs)

TIGER files

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