1. Maps and Layers Topics Summary, Review Question, and Next… Maps (4)
Geogrpahy, KHU,
Jinmu Choi
Topics
Maps (4)
Features and Attributes in a Map (5)
Layer and Drawing Symbols (4)
Drawing Categories and Quantities (5)
Classification Methods (3)
Raster Data and Their Drawing (5)
TIN Visualization (4)
Summary, Review Question, and Next…
GISProject

2. Maps The presentation of geographic data
The interface between geographic data and our perception
An abstraction of geographic data for a particular class of user
Now, maps are static or dynamic
The creation of informative and aesthetic maps are necessary
GISProject

3. Use of Maps To identify what is at a location
To locate where you are, e.g. GPS
To identify distributions, relationships and trends, e.g. exploratory analysis
To integrate data from diverse sources into common geographic reference
To solve spatial problem, e.g. suitability
To find a path, e.g. routing
To model events, e.g. various simulation
Sharing knowledge about our world
GISProject

4. Spatial Relationships in Map
Main spatial relationship
Adjacency and neighborhood
Connectivity
Containment
Extra information
Difference in elevation
Relative position
GISProject

5. Map Elements Data frame Surroundings Other map elements
Main part that present geographic data
Several layers in one frame
Several frames in one layout
Surroundings
Cartographic context such as scale, arrow, legend
Other map elements
Title, text, pictures
GISProject

6. Display with Discrete Features
Feature types
Discrete phenomena
Continuous phenomena
Discrete features
Points: geographic features too small to be depicted as lines or areas
Lines: too narrow to be depicted as areas
Polygons: closed figure with the shape and location of homogeneous characteristics
Hwy 101
Lake
Well
Woods
GISProject

7. Display with Continuous Features
Images and Grids
Image sources
Aerial photographs
Satellite images
Grid sources
Continuous phenomena
Sampling and interpolation
Raster data type
Two-D matrix of cells
Resolution based on the cell size
GISProject

8. Display with Surfaces Surfaces The shape of the earth’s surface
Sun illumination, elevation, slope, aspect
Raster data
DEM
Cell has elevation value
Vector data
TIN
Node has
elevation value
GISProject

9. Attributes for Mapping
Type (or thematic) attributes
Coded (or nominal) value: numeric value for types
Used for the symbol
selection
Measured attributes
Discrete numeric value: countable objects
Real numeric value:
measured or calculated
value
Used for the size of symbols
GISProject

10. Display with Attributes
Classified attributes
Nominal value or Numeric value
Color for each class
Labeling
Descriptive string: name of features
Multiple attributes in different tables or database
Object identifier for connecting various external attribute tables
GISProject

11. Layers Basic unit of geographic presentation in ArcGIS
layout
layers
Basic unit of geographic
presentation in ArcGIS
A set of same type geographic features
The same data for multiple representations with different attributes or drawing method
Editing data automatically updates representations
Sharing representation without duplicate data (.lyr file)
frame
GISProject

12. Points with Symbols Points with marker symbols
Character marker symbol: TrueType font
Simple marker symbol: a square or circle
Arrow marker symbol: TrueType font
Picture marker symbol:
Bitmap (.bmp) or enhanced metafile (.emf)
Multilayer marker symbol: composite symbol
GISProject

13. Line with Symbols Lines with line symbols Cartographic line symbol
Width, color, parallel offset distance, pattern…
Hash line symbol
Combined with cartographic lines
Marker line symbol
Use defined pattern
Multilayer line symbol
Combines other symbols
Cartographic line +
hash line = railroads
GISProject

14. Areas with Symbols areas with area symbols Simple fill symbol
Color, outline style…
Line fill symbol
More fill pattern with
simple fill symbol
Marker fill symbol
Use defined pattern
Gradient fill symbol
Blend of two color
Picture fill symbol
Use of bitmaps of
enhanced metafile
Multilayer fill symbol
Combines other symbols
GISProject

15. Category Symbol with Color
Simplest drawing
All features with the same symbol
Categories by unique value
Attribute for an important subdivision of the feature type
Unique symbols for each unique value 12
Pole 12
Railroad 12
Residential 1
Pedestal 46
Highway 46
Lake 61
Transformer 69
Canal 69
Park
GISProject

16. Category Symbol with M-att.
Categories by unique combined field value
Unique combinations of up to three values
Vegetation maps can be separated by dominant types
E.g. land use and historic district
GISProject

17. Quantity with Color Quantities by color Data type: ratio, interval
Continuous phenomena representation
Elevation, temperature, amount of resource
Color ramp
Using a set of graduated color
30-49
50-79
80-99
GISProject

18. Graduated Symbol Quantities by Graduated symbols
Using size of symbol: ordinal data
Rank representation for comparison
For drawing, Larger symbols first and the smaller symbols afterward
City ranks with graduated marker symbol based on the size of population .
1-2
3-6
7-9
10-14
GISProject

19. Proportional Symbol Quantities by proportional symbols
Using size of symbol: interval or ratio data
Exact proportion to the attribute value
No categorical and classification values
Continuous graduation of symbol size
Larger symbols drawn first 1 10
0.1
1.2
45.1
97.3
GISProject

20. Classification Methods
To subdivide attributes by desired criteria
Natural breaks
To determine natural clusters of attributes
Jenk’s algorithm
Minimum variance within a class and maximum variance between classes
Graduated symbol or color
Good to uneven distributions of attributes
GISProject

21. CM (Cont.) Defined interval Equal interval
Classes divided by precise numeric increments
Decision on the interval will decide # of classes
Age distribution, income level, elevation
The first and last classes disproportionate feature number
Equal interval
To divide ranges of equal value intervals
(Max-Min)/(# of classes) will decide range
All classes are
in the same range
GISProject

22. CM (Cont.) Quantile Standard deviation Equal number of
features in each class
Effective for ranked values
Rank of sales performance
Ambiguous natural distribution (clusters)
Good to linear distribution
Standard deviation
Fractional deviations from a mean value
One, one-half, one-third,
one-quarter std.
Good to symmetric
distributions
Population density or
accident rates
GISProject

23. Raster Data Data value: Thematic data vs. Continuous data
Thematic data : land use cover
Classified data or categorical data
Continuous data
Continuous phenomena: elevation, slope,…
# of theme: Thematic data vs. Spectral data
Thematic data: a specific theme (phenomenon)
Fire, slope, elevation, aspect….
Single band or layer
Spectral data: multiple phenomenon
Aerial photography or satellite imagery
Panchrometic or multispectral bands
Scanned Picture
No geometry
GISProject

24. Raster with Unique Value
Drawing by unique value
Land use/cover, soils type, ownership
Cell values are discrete spatially
Descriptive or numeric attribute
The number of unique values (classes) should not exceed 25
3-7 are most efficient
water
forest
residential
industrial
GISProject

25. Raster with Graduated Color
Drawing by graduated color
Cell values are continuous spatially
Elevation, slope, pollution contaminants, Population density
Denser concentration use darker
1-4
5-8
9-12
13-15
GISProject

26. Raster with Stretched Color
Drawing cells stretched by graduated color
Cell values are continuous spatially
Spectral value, calculated value, sun illumination angle
High
Medium
Low
GISProject

27. Raster with RGB Composite
Drawing by RGB composite
Use three bands for each visual channel
True color composite
Blue color: Blue band, Green to Green, Red to Red
False color composite
Blue color: Green band, Green to Red, Red to Near Infrared
GISProject

28. TIN Visualization Triangulated irregular network (TIN)
Efficient to represent a surface
Sampling and interpolations
Elements of a TIN
Node: point has continuous real value
Edge: line connects nodes and separates area
Face: area defines a plane, a slope, a direction
Normal: perpendicular vector to a face
To calculate illumination, aspect, and slope z y x
node
edge
face
normal
GISProject

29. Contour and Aspect with TIN
Contour with a graduated color ramp
A face can have several contour lines
Each zone drawn with a color from color ramp
Aspect with a graduated color ramp
Cardinal direction of the normal of a face
N: 0, E: 90, S: 180, W: 270 z
960m
950m x y z
normal
face
aspect x y
GISProject

30. Representation using TIN
face
normal
sun
Hillshading
Realistic view of a terrain
Calculating the angle between the direction to the sun and the normal to a face
Brightness of reflected light proportional to the cosine of the angle
Lower angle (sun direction), higher value z y x
face
normal
sun
GISProject

31. Summary Map and feature display Map elements Drawing with Symbols
Classification Methods
Raster Drawing Methods
Drawing with TIN data
GISProject

32. Next… Lab: Working with Layers and Layouts
Lecture: Structure of geographic data
Assignment
Read Modeling Our World
Ch3. pp ; Ch 4
GISProject