Lab_4 symbology

Symbology

Prof. Dr. Sajid Rashid Ahmad

[email protected]

Atiqa Ijaz Khan _ Demonstrator

[email protected]

Symbology

• Symbology means to deal with color, shape, size, patterns, markers, widths, andother properties which a feature concerned.

• Different Symbology helps in displaying of different information.

• It also varies with the scale.

• It deals with all information available on a map display.

• It also comes in with specific standards and also varies according to the users.

• The main aspect is to display the required information in a way that it is readableand useful to the users.

Sunday, December 21, 2014Institute of Geology, University of the Punjab

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• By Right clicking the

Symbol selector, it offers

multiple options to colors,

and its outline, and its

width.

• One can add symbols.

• Can save it for future.

• And can add different

styles.

Symbology in ArcGIS

• In Arc-GIS, we deal with 5 types of Symbology:

• Features: Draw all features with a single color.

• Categories: Draw features on the basis of unique field.

• Quantities: Draw using color to show values.

• Chart: Draw pie chart for each feature.

• Multiple Attributes: Draw quantities for each of the category.

• TO ACCESS SYMBOLOGY:

• Right click on any shapefile to get into the context menu, and then select Tab ofSymbology, under the layer Properties, after clicking Properties from the menu, toaccess its options.


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How to Access Symbology

in Arc GIS 10.1

1. Features

• It only support 01 single color at a time to 01 single feature.

• Regardless of the text or number field type.

• Regardless of feature type.

• It can be accessed by:

• Symbology tab, under the Properties of any shapefile, or

• Directly by ‘Symbol Selector’, within Table of Content, mentioned earlier.

• Its not permanent, unless it is saved to a file called ‘Layer file’ with extension‘.lyr’.

• That used to preserve the properties of Symbology as it is, as define by the user.

• Can be loaded any time to use further.


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Symbol

Selector,

under

Table of

Content

Feature: Single Symbol,

under Symbology

2. Categories

• It offers 3 options:

• Unique values

• Unique values up to 03 fields

• Multiple fields

• One can Add Values and Add All Values.

• Also can remove them, in the same way.

• It also gives the count of the features within that value range.

• Graphic View:

• Shows colors/ramp.

• Un-checking it, shows its names.


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10Graphic View


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For Polygon Feature Type

In Unique Values Option:

• Select a Value Field

• Select a Color Ramp

• Add All Values, or

• Add Values (1 by 1)

• OK

• See Result


12Upper Left: For Line feature

Lower Right: For Point feature


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In Unique Values for up to 3 fields

3. Quantities

• It is concerned with numerical values only.

• It is not related to any of the Text field.

• In Arc GIS, there are 4 of its types:

• Graduated colors

• (Mostly for Polygon)

• Graduated symbols

• (Mostly for Point)

• Proportional symbols

• (For All)

• Dot density

• (For Polygon Only)


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Quantities Classification

• Under the Quantities, there is an option of Classification, available only forGraduated Colors and Symbols, divided into 05 classes by Default & ranges from01 – 32 in all.

• They are:

• Manual

• Equal Interval

• Defined interval

• Quantile

• Standard Deviation

• Geometric Interval

• Natural Breaks (Jenks) _ Default


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Manual Method

• Number of classes are pre-

define.

• Interval size can be varied.

• One can adjust the division

manually:

• Blue lines are showing

automatically adjusted

lines

• Red line is showing

Manually adjusted line.


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Equal Interval:

• It will create classes of

equal interval range.

• One can adjust the number

of classes.

Example:

Pakistan map is divided into 4

equal classes on the basis of

Area.


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Define Interval:

• It will create classes of

interval size as defined by

user.

• In this case, number of

classes are define by

interval size.


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Quantile Interval:

• It will make the division on

the basis of number of equal

features.


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Geometric Interval:

It is used when the data is not

normally distributed.

Produces cartographically

appealing results.

Minimizes the variance within

classes.


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Standard Deviation:

• It will make the division on

the basis of standard

deviation from the mean.


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Above: 1 Standard div. with 04 classes

Below: ½ Standard div. with 07 classes

a. Graduated Colors

• The Most common of the type.

• With this, quantitative values are grouped into ordered classes.

• Within each class, single color is assigned to all features.

• Each class is assigned a graduated color from smallest to largest.

• Displays features in range of shades of colors that changes gradually.

• The color range is called: ‘Color Ramp’.

• It most effected on ‘Polygon-Feature Type shapefile’, than point or line.

• As it shows the color differences colorfully.


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For Polygon Feature

Type

Normalization offers:

• Percentage

• Log

• Numeric Field Values


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Range: Can be adjusted

manually, by simply clicking on it.

• In the same way, Symbol and

Label can also be adjusted

Showing the Class Limits, instead of Class

Boundaries, in case, when it is not Checked, as

mentioned above.


26Upper Left: Point

Lower Right: Line

b. Graduated Symbols

• It is normally used with ‘Point-Feature Type’.

• But can be shows by:

• Line: It is displayed by line of gradually changing sizes.

• Polygon: It is displayed by point of gradually changing sizes.

• Displays by gradual marker sizes.

• It draws only for 1 single field value.

• It is used to show Relative Values.


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Graduated Symbol :

Point


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Upper Left: Line

Lower Right:

Polygon


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For Polygon:

• Symbol by Template

• Background Color

• It can also be classified.

• It can be normalized on the basis of:

• Percentage

• Log

• One can change the symbol type, through the option of ‘Template’.

• Its size can also be varies, from lower to upper (min - max), through the option of‘Symbol Size’.


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32Normalization

Upper Left: Percentage

Lower Right: Log

c. Proportional Symbols

• It varies proportionally with the normalized field.

• It goes with all feature type of shapefile.

• It displays best when the field values are not to wide.

• It is used to show Exact Values.

• As it displays the symbols on right and larger differences.

• In case of narrow wide range of values, it is tough to adjust the symbols, as itbecomes too crowded to display on screen.

• There is a fixed relationship between proportional symbols and attributes.


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• For Polygon feature

up to 09 divisions.

• Valued upon ‘Area’

from attribute table.

• Smaller area,

smaller symbol

size


35• Value: Any1 field from

attribute

• Normalization: From field

• Exclude: Fields from

attribute table

• Unit: Unknown fits to the

screen, so to display only

purpose, otherwise adjusted

with user define units

• Shape: Could be circular

and square

• Maximum number of

symbols in a legend are:

09

• With the range of: 1,000-

1000,000

• It can be arranged on the basis of any filed selected from the attribute table.

• The lowest value from the filed gets the smallest size of symbol.

• Shape: Could be circular and square.

• Maximum number of symbols in a legend are: 09. (01-09)

• Default is: 03

• Must with the range of: 1,000 - 1000,000

• When ‘Units’ are not specified, one can adjust the symbol size by Min Value.

• In case it is define, it actually multiplies the filed value by map units.


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On Varying the Units,

different options available

are:

• Symbol shape:

• Circle or

• Square

• On the basis of:

• Area (Fits best)

• Radius (1/2 of width)

• Background color

• Outline

• Color

• Width


38Varying Units:

• Upper Left: In unknown

units

• Lower Right: On

multiplication to YARDS

d. Dot Density

• Only for Polygon layer.

• The greater the values, the greater the number of dots or density, within theboundary layer of polygon.

• It displays randomly.

• There is a fixed relationship between number of dots and attributes.

• But it may differs from the actual attribute values.

• For Example:

• 1 dot = 1,000 (in our example)


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Result of Dot Density at

1:11,396,724

Result of Dot Density at

1:6,000,000

• Dot density is Scale dependent.

• It is maintained by:

• Dot Size: As one zoom in, its size increases.

• Dot Value: Value per dot decreases, so number of dot increases as one zoom in.

• By Default:

• Dot Size = 2 (ranges from 01 - 11)

• Dot Value = 1000 (ranges from 51,000 - 150)


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On Zoom In. Dot Density

varies by Size, but Value

per Dot remain same.


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On Zoom In. Dot Density

varies by Value, but

Value per Dot does not

remain same, it

decreases, so number of

dot increases.


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Lab_4 symbology

Education

institute of geology

properties of symbology

different symbology

access symbology

tab of symbology

symbology tab

single color

single feature