copyright © 2006 by maribeth h. price 1-1 chapter 1 introducing arcgis

Copyright © 2006 by Maribeth H. Price

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Chapter 1

Introducing ArcGIS


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Outline

• What is GIS?

• Some GIS applications

• Introducing the ArcGIS products

• How does GIS work?– Basic data formats– The ArcCatalog interface


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What is GIS?

• Software combining spatial mapping and analysis with database management


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With GIS you can:

• Create maps, graphs, and reports

• Create and manage map data

• Analyze spatial relationships

• Overlay map data from different sources

• Manage and display database information

• Locate addresses

• Analyze utility and transportation networks


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Example

– soils– geology– vegetation

communities– slope– aspect

– distance to water– distance to roads– satellite-derived

vegetation index (NDVI)

– satellite-derived moisture index (NDMI)

Compare 1998 horseback thistle survey to easily assessed environmental parameters

Predicting thistle occurrence in Badlands National Park


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Thistle habitat prediction map


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Application—Wildlife habitat model

• HABCAP model (U.S. Forest Service)– Uses available vegetation/roads data– Assesses suitability of a forest stand

• Availability of forage (FV = 0-1)• Availability of cover (CV = 0-1)• Proximity of forage and cover (PV = 0-1)

– Both together are more valuable than either alone

• Distance from roads

– Each stand is given a final suitability score 0-1– Uses a variety of GIS analysis techniques


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Each polygon is assigned a coefficient for cover (CV) and forage (FV) availability based on the vegetation type and structure (COVSS)

Reclassification


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Dissolving

Then the polygons are dissolved, removing the internal boundaries between polygons with the same designation.

Based on the coefficient values, the polygon is given the designation as primarily cover (C), primarily forage (F), or both (B)


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Proximity analysis

Ideal habitat area based on proximity:

B (contains both forage and cover)

Areas of F polygons that are close to the boundary of a C or B polygon

Areas of C polygons that are close to the boundary of a B or F polygon


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Buffering

PV = 1.0PV = 0.5PV = 0.2

First we extract only the C and F polygons. Because of the previous dissolve, the boundaries of these polygons all represent ideal habitat edges

Multiple buffer zones are created inside each polygon, representing distances from the boundary. Closer areas get a higher suitability rating.


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Calculation of suitability

• HS is the final suitability rating for each polygon

• Use the coefficients (0-1) determined for cover (CV), forage (FV) and proximity of cover and forage (PV)

HS = (3*FV * CV * PV) / 5

HS


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Road buffers

HS

Buffers are created around primary and secondary roads. Primary roads get larger buffers. Areas close to roads have HS halved.

Roads

Final HABCAP result


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What is ArcGIS?

Description and history of the ESRI GIS family


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A history of productsArc/Info

Arc

ArcPlot

Info/Tables

ArcEdit

GRID

ArcView 3x

ArcGIS

ArcMap

ArcInfo Workstation

ArcCatalog

ArcToolbox

ArcGIS Desktop

Coverages Shapefiles Geodatabases


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ArcGIS Desktop

ArcCatalog

ArcMap

ArcToolbox


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ArcGIS functionality

Three levels of functionality and cost

$$$ArcInfo

$$ArcEditor

$ArcView

Same interface and programs

More tools in the toolbox


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ArcGIS Extensions• Spatial Analyst• 3D Analyst• Publisher/ArcReader• Network Analyst• Maplex• Geostatistical Analyst

• Extensions are additional tools and commands that can be added to the core ArcGIS interface

• Appear as new toolbars and toolsets in ArcCatalog


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Licensing

• Floating point licenses– ArcInfo only– Central server checks out licenses– Requires a dongle and a license file

• Standalone licenses– Uses a registration file/ register online– No dongle needed– Available for ArcView and ArcEditor only


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How does GIS work?

Data storage

The ArcGIS Interface


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GIS data models

Vector model Raster model


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Vector model

Vertices

Polygon

Points

Nodes

Line

X

Y

Features are stored as a series of x-y coordinates in a rectangular coordinate system.

Many different coordinate systems may be used.


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X-Y Coordinate systems/units:Longitude-latitude (degrees)State Plane (feet)UTM (meters)

Some familiar coordinate systems can be found on a topo map.


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Features linked to data

Each feature is linked to an entry in a data table containing information about the feature.


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Feature classes

A collection of similar objects with the same attributes

States feature class

Cities feature class


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Advantages of vectors

• Precise location of features

• Storing many attributes

• Flexible for cartography

• Compact storage of information

• Ideally suited for certain types of analysis, especially areas, lengths, connections


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The raster data model

Rows

ColumnsX, Y location

Raster data fileN rows by M columns

X, Y location

Georeferenced to earth’s surface


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Types of raster data

Discrete raster: land use

Continuous raster: DEM

Continuous raster: image

Discrete raster: roads


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Continuous data

• Raster is the best way to store continuously changing values such as elevation

• Analysis faster and more flexible than vectors for many applications

• Some analysis only possible using rasters


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Raster analysis functions

Density

Least cost path

Distance Interpolation

ViewshedBuffers


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Impact of resolution

• Storage space increases by the square of the resolution

• Portraying large areas at high precision is problematic

90m resolution

10m resolution


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Storage of attributes

• Roads may have other attributes: ownership, speed limit, number of lanes, etc.

• Would need a new raster for each attribute

• Only numeric attributes may be storedRaster contains 1 value

indicating a single attribute—road type for example


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The ArcGIS InterfaceMenu bar

Tool barsTear-off/dock

Display window

Context menu

More toolbars


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The Tools toolbar

Zooming and panning

Full extent

Pointer tool

Identify attributes of features

Find text in attributes

Measure distances

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15


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Context menus

Right-click name

Right-click symbol

Left-click symbol

Menus pop up when certain objects are clicked


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What is a layer?

• Spatial data file• Associated

properties• Held in memory

in ArcMap• Used as inputs

to functions/tools• May be saved as

a file


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Layer Properties Property tabs


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Data formats

Coverages Shapefiles Geodatabases


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Topology• Information and rules stored about spatial

relationships between features and feature classes

A

B

Polygon A is composed of a label and two arcs. Polygon A is adjacent to polygon B and shares one common arc.

A dangle error—the two lines fail to connect

Correct topology

Self-intersecting loop error

gap

overlap

Polygon errors


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Topology rules

Shannon County

Bennett County

Pine Ridge Indian Reservation

South Dakota

Nebraska

Topology rules establish how features should be spatially related.

Topology rules may apply within a layer or between layers.

• No gaps or overlays between counties

• The Pine Ridge and Bennett County boundaries should match

•The South Dakota and Pine Ridge boundaries should match

These three layers show several topology errors.


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ShapefilesShapefiles in Windows Explorer

Shapefiles in ArcCatalog

Coincident boundary

•One feature class

•Multiple files

•Simple features

•No topology

•Dbf tables

•From ArcView


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Coverages

Multiple feature classes

Topological features

Many files

Info tables

From Arc/Info

Topology is information stored about spatial relationships between features. Polygon A is composed of a label and two arcs. Polygon A is adjacent to polygon B and shares one common arc.

A

B


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GeodatabasesSingle file

Multiple feature classes

Access database technology

Feature datasets

Simple and topological features

Validation rules

Customized object behavior


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Other types of data

Rasters Tables

Layer files CAD Drawings


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Geoprocessing• Stringing together commands and analysis

functions to achieve a resultMenus

Tools

Command line

Model builder

Scripts


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Important

• Although Windows permits spaces in file and folder names, in GIS they are a BAD IDEA.

• They often work, but sometimes a certain program or function will fail if it encounters a space in a folder name.

• Real GIS users FLINCH when they see spaces anywhere in folder/file names—even when they’re allowed!


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Metadata• Contains information about data that people need to properly understand and use the data• Created with and copied with data

Create Edit

Update Import Export

Fig. 22. The metadata toolbar lets you create, view, and edit metadata for your layers.


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AVOID SPACES IN FOLDERS and FILENAMES

Spaces are Evil

http://en.wikipedia.org/wiki/Image:Vader.jpg


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Connecting to folders


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The ArcCatalog Interface

Folder tree Display window

Menu/tool bars


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Three view modes

Contents Preview Metadata


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Tables in ArcCatalog


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Getting Statistics


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File Properties

Right-click file name


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Did I mention that you should avoid spaces in folder and file names?

http://en.wikipedia.org/wiki/Image:Vader.jpg

copyright © 2006 by maribeth h. price 1-1 chapter 1 introducing arcgis

Documents

proximity of forage

cover pv

proximity of cover

forage fv availability

gis work

gis applicationsintroducing

pricewith gis

forage pvhs