gis for environmental science ensc 3603 class 7 2/03/09

GIS for Environmental GIS for Environmental ScienceScience

ENSC 3603ENSC 3603

Class 7Class 72/03/092/03/09

Today's ObjectivesToday's Objectives

• Quiz

• GIS Data GeoStor Quick Start Guide

• NRCS Web Soil Survey

• Vector Data

• ArcGis, ArcCatalog

GIS DataGIS Data

• GeoStor 5 quick start guide• http://www.geostor.arkansas.gov/Portal/ptk?

command=quickstarthelp.jsp

• NRCS Web Soil Survey• http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm

DataData

•Thematic Layers•A GIS stores information about the world as a collection of thematic layers that can be linked together by geography.

DataData• Geographic data record the locations and

characteristics of natural features or human activities that occur on or near the Earths surface.

• Data Types:

• Vector Raster Surface

Vector DataVector Data

• Vector Data: A conceptual representation of geographic features.

• Vector Data Model: Object based approach to represent discrete objects.

• Vector Data Model Concepts use graphical elements: – Points– Lines or arcs– Polygons or areas– These are also known as Feature Classes

Reality as Vector DataReality as Vector Data• Real-World

entities are abstracted into three basic shapes

Points(Man-holes)

Lines(Roads, Sewer lines)

Polygons (Wetlands, Fields,Buildings)

Vector DataVector Data• Point, Line and Polygon entities.

Vector DataVector Data• Points: Chicken houses in Washington County

Vector DataVector Data• Line: Washington County Roads

Vector DataVector Data• Polygon: Washington County Soil Series


Raster data Structure Converted to Vector dataStructure


• Feature classes pertain to a particular theme such as vegetation, land parcels, drainage and transportation etc.

• Feature classes are organized into layers

• Layers only have one type of graphical element.


• Representing vector data differently at different scales:– Cartographic generalization – line and area

objects are represented by more coordinates at a large scale than at a small scale.

– Cartographic symbolization – Vector data are represented by different symbols that visually distinguish them from one another


• Topology: Spatial relationships– Adjacency: neighborhood– Containment: Inclusion of one spatial object

within another– Connectivity: Linkages among spatial

objects


• Topology: Spatial relationships– Adjacency:

neighborhood– Polygon C is Adjacent

to Polygons B and D


• Topology: Spatial relationships– Containment:

Inclusion of one spatial object within another.

Polygon A is Contained within Polygon B


• Topology: Spatial relationships– Connectivity:

Linkages among spatial objects.

Point A is Connected to Point B

A

B


• Vector-based GIS Data-Processing:– Input– Analysis– Output


• Input functions– Digitizing tables– Image scanning– Importing data


• Data input functions:– Acquisition by digitizing, purchasing,

collecting new data by GPS, surveying or photogrammetric and remote sensing methods

– Editing to clean and inspect data.– Formatting or translating to convert data to

a specific physical database format.– Linking graphical data to associated attribute

data.


• Analysis functions:– Nontopological Analysis:

• Attribute database query– Structured Query Language (SQL)

• Address geocoding– Or Address matching, TIGER files

• Area Calculation• Statistical computation

– Mean, max, min and standard deviation computed for items in attribute tables.

Attribute database query, Structured Query Language (SQL)

HI1

42

34

F1

D5

46

E1HI2

38

40

35

B4F2

33

G339

D3

K1

A1

A4

E2

D8

L8

AG PARK

A5

C4

C3

A3

B5

32

C2

A6

C1

K2

D6

G6

L2

D2

F8

A7

B6

L5

PV2

FD8

A3A

I3

E4

D1

38A

G2

E5

37

G4

32A

A2

E3

36

G5

D7

B7

G7

HA

I1

B3

HC

D4

B10

44

L3

I6F13

F10A

43

34B

K5

HB

FS9

34A

F9

HD6

HD7

C5E

A8

41

HD3

FD1

C5W

K3

34C

F10

HD5HH3

HD1

I4

HD4

HH2

F4

34D

C8E

C7E

C6E

K4

A2A

32B

HH3E

HH1

B8

L1A

E10

I5

C7W

C6W

G8

HD8

B9

B3

HH3C

C8W

F6

F7

G1

FS7

F5

FS6

G8A

35A

I2A

B1

E8

HH3A

FS8

L1

HH3B

F12

F11

UA

EX

HH4

PF3A

E7

E6

I2

L4A

46A

FD6

L6FD7

EN6

G10

FD5

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G8B

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L4

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EN5

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F3

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EN7

33A

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3D

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2B1AL7 F

D3

G1 0

A

36A

EN4

Arkansas Agricultural Research and Extension Center

LegendChisel plow 1994Pond

¬0 1,000 2,000500 Feet

Fields chisel plowed 1994

Attribute database query, Structured Query Language (SQL) Map Result

GeocodingGeocoding

Mapquest uses Geocoding to find

locations.

Database of address used toMap locations on a map.

Statistical computation, Mean, max, min and standard deviation computed for items in attribute tables

Field F1Soil pH

Vector DataVector Data• Topological Analysis

– Layer-based Analysis• Reclassification

– Aims to reduce categories of attribute data

• Layer-based Overlay analysis

– Topological Overlay Operators for polygon on polygon

• UNION: Keeps all area in both layers

• INTERSECT: Keeps only parts of the first layer falling within the second layer

• IDENTITY: keeps all layer features

• CLIP: Cuts out a piece of the first layer based on the second

• ERASECOV: erase part of first layer based on the second

• SPLIT: divides the first layer based on the second

• Network analysis


– Network analysis• Linear features that are interconnected

– Examples, highways, railways, rivers transit routes utility distribution systems.

– Example problem: Find shortest route between two points.

– Line segments and junctions can have resistance.


• River Network


– Feature-based analysis• A Buffer is a zone with a specified width that

surrounds a spatial feature.– Buffering

• Used for neighborhood analysis

• Feature-based overlay analysis– Example, point in polygon


• Buffering around a point

Buffering around lines


• Overlay analysis– Represents the world in layers– Combines human/social with

environmental– Data must be measured,

generalized, and quantified– Both visual and analytical

analysis

Types Visual, Boolean, Arithmetic


• Output Functions– Vector map Composition

• Graduated Symbols• Graduated Colors• Charts• Contour Lines• 3-D Perspective Views

– Vector-raster conversion

Class ProjectClass Project

A 200 word statement describing a problem to be addressed by the project. Include an:

Introduction

Objectives

Methods – Data, Software, Analysis

References

Example found at:http://www.uark.edu/depts/agronomy/farm/GISFES09/

GISFES09.HTML

For Next timeFor Next time

• Chapter 5 in Lo (2007)

• Project proposal due February 5th

• ESRI Module 2 due

"Focus not on the commotion around you, but the opportunity ahead of you." - Arnold Palmer

"Achievement is largely the product of steadily raising one's levels of aspiration and expectation." - Jack Nicklaus

gis for environmental science ensc 3603 class 7 2/03/09

Documents

graphical data

data types

datageographic data

new data

vector data model concepts

vector datapoints

spatial relationshipsadjacency

vector dataanalysis