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8/10/2019 Image Analysis Intro

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Using ArcViewImage AnalysisVersion 1.1 - Beta

E N V I R O N M E N T A L S Y S T E M S R E S E A R C H I N S T I T U T E , I N C .

Enhanced Image Integration, Display and Analysis


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Copyright 1999 ERDAS, Inc.

All Rights Reserved.

Printed in the United States of America.

DATA CREDITS

ERDAS extends its thanks and appreciation to the following data providers and other organizations who

either supplied or prepared example data and technical explanations used in this document:

ADAR Airborne Sensor data courtesy of Positive Systems, Inc., Kalispell, Montana.

Landsat MSS, Landsat TM, and IRS-1C data courtesy of Space Imaging EOSAT, Thornton, Colorado.

SPOT data courtesy of SPOT Image Corporation.

AEROTERRA S.A., Argentina.

Infocarta, S.A., Spain.

U.S. Geological Survey, EROS Data Center, Sioux Falls, South Dakota.

ESA/EURIMAGE, Rome, Italy.

BCD Council of Governments, Charleston, South Carolina.

Westvaco, Inc., Summerville, South Carolina.

ERDAS, Inc. ERDAS Field Guide, 4th ed. Atlanta: ERDAS, Inc., 1997.

Maling, D.H., Coordinate Systems and Map Projections, 1992 Second Edition, Pergamon

Press, Inc., New York.

The information contained in this document is the exclusive property of ERDAS, Inc. This work is

protected under United States copyright law and the copyright laws of the given countries of origin and

applicable international laws, treaties, and/or conventions. No part of this work may be reproduced or

transmitted in any form or by any means, electronic or mechanical, including photocopying or

recording, or by any information storage or retrieval system, except as expressly permitted in writing

by ERDAS, Inc. All requests should be sent to Attention: Manager, Technical Documentation; ERDAS,

Inc.; 2801 Buford Highway; Atlanta, GA; 30329-2137; USA.

The information contained in this document is subject to change without notice.

DATA DISCLAIMER

EACH DATA VENDOR INCLUDED IN THIS WORK IS AN INDEPENDENT COMPANY AND, AS

SUCH, ERDAS AND ESRI MAKE NO GUARANTEES AS TO THE QUALITY COMPLETENESS

AND/OR ACCURACY OF THE DATA. EVERY EFFORT HAS BEEN MADE TO ENSURE THE

ACCURACY OF THE DATA INCLUDED IN THIS WORK BUT THE INFORMATION IS DYNAMIC

IN NATURE, AND IS SUBJECT TO CHANGE WITHOUT NOTICE ERDAS, ESRI, AND EACH

DATA VENDOR ARE NOT INVITING RELIANCE ON THE DATA, AND ONE SHOULD ALWAYSVERIFY ACTUAL MAP DATA AND INFORMATION. ERDAS AND ESRI DISCLAIM ALL OTHER

WARRANTIES OR REPRESENTATIONS, EITHER EXPRESSED OR IMPLIED INCLUDING, BUT

NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A

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IF ADVISED OF THE POSSIBILITY THEREOF.

RESTRICTED/LIMITED RIGHTS LEGEND

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At a minimum, use, duplication, or disclosure by the Government is subject to restrictions as set forth in

FAR 52.227-14 Alternates I, II, and III (JUN 1987); FAR 52.227-19 (JUN 1987) and/or FAR

12.211/12.212 (Commercial Technical Data/Computer Software); and DFARS 252.227-7015 (NOV

1995) (Technical Data) and/or DFARS 227.7202 (Computer Software), as applicable.

ERDAS and ERDAS IMAGINE are registered trademarks and Geographic Imaging by ERDAS and

geographic imaging made simple are service marks of ERDAS, Inc.

ESRI and ArcView are registered trademarks in the United States and are either trademarks or registered

trademarks in all other countries where they are used; Avenue, the ESRI globe logo, and the ArcView

Image Analysis logo are trademarks; and www.esri.com is a service mark of Environmental Systems

Research Institute, Inc. Other companies and products mentioned herein are trademarks or registered

trademarks of their respective trademark owners. ArcView GIS uses Neuron Datas Open Interface.


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C H A P T E R 1

Introduction to the ArcViewImage Analysis extension

Imagery of the earths surface has become an integral part of todays

geographic information systems (GIS) and desktop mapping systems by

providing realistic backdrops to geographic databases, allowing us to

quickly update details such as street or land use data. Images also provide

us immediate feedback after environmental hazards such as fires or oil

spills. The ArcView Image Analysis extension allows ArcViewGIS

users to utilize digital image data for making faster and more informed

decisions.

With the ArcView Image Analysis extension, you can perform manytasks:

Import and incorporate raster imagery into ArcView GIS.

Categorize an image into a number of classes corresponding to land

cover types like vegetation.

Evaluate images at different time periods to identify areas of change.

Identify and automatically map a land cover type with a single click.

Find areas of dense and thriving vegetation in an image.

Enhance the appearance of an image by adjusting contrast andbrightness or by applying histogram stretches.

Align an image to a map coordinate system for precise area location.


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What you can do with the ArcView Image Analysisextension

While the potential uses of the ArcView Image Analysis extension are nearly limitless, the

extension is designed primarily for natural resource and infrastructure management

applications. These applications include forestry and agriculture, environmental

assessments, engineering and infrastructure management projects like facility siting and

corridor monitoring, and general geographic database update and maintenance.

With the ArcView Image Analysis extension, you can perform tasks that range from

simply displaying images to performing detailed spectral analyses and detecting

temporal change.

The tools available in the ArcView Image Analysis extension provide:

Access to industry-standard image data types and formats with simple-to-use

importers and direct read/write utilities.

Fast image display and manipulation for productive use of large image files within anArcView GIS project.

Three levels of image enhancement capabilities created to optimize image

visualization and interpretability. These functions enhance the contrast and brightness

of your images, apply standard histogram stretches, or apply custom stretches to

enhance specific data or features of interest.

Spatial enhancement filters designed to optimize interpretability and output of both

continuous and thematic imagery. These functions will let you sharpen or smooth

imagery to suit your interpretation and output needs.

Image-to-map rectification tools for coregistering aerial and satellite imagery to a

project map base. These tools will also let you perform image shifts and local

registrations.

Analysis capabilities for multispectral categorization, vegetation mapping, automated

feature mapping, and temporal change mapping with both continuous and thematicimagery. These functions let you easily incorporate imagery into any project, extract

usable information, and integrate the results into a project.

Tools to input and output GRID files, which can be used with the ArcView Spatial

Analyst extension.

Customization with Avenuefor special application development.


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The following are some example applications of the ArcView Image Analysis extension.

These examples range from database updating to analyzing vegetation for signs of

stress.

Update databases

There are many kinds of imagery to choose from in a wide range of scales, spatial and

spectral resolutions, and map accuracies. Aerial photography is often the choice for map

updating because of its lower cost.

With the ArcView Image Analysis extension, you can easily coregister imagery to your

base map. Then, using Image Analysis tools and the ArcView GIS capabilities youre

already familiar with, you are able to use imagery to identify changes and make revisions

and corrections to your geographic database.

This example illustrates the use of an orthophoto for accurate revision of an existing database.


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Categorize land cover and characterize sites

Transmission towers for telecommunications must all be visible from each other, must be

within a certain range of elevations, and must avoid fragile areas like wetlands. With theArcView Image Analysis extension, you can categorize images into land cover classes

to help identify suitable locations. You can use imagery and analysis techniques to

identify wetlands and other environmentally sensitive areas.

In the image below, Categorize was used to divide the image into a number of classes.

You can highlight those areas not suitable for a tower in your view. With this

information, the towers can be sited appropriately.

This example shows an automatically derived land cover categorization with transmission toweravoidance areas (wetlands) highlighted in yellow.


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Identify and summarize natural hazard damage

In a forest hit by a hurricane, you can use the mapping tools of the ArcView Image

Analysis extension to show where the damage occurred. With other tools, includingstandard ArcView GIS tools, you can show the condition of the vegetation, how much

stress it suffers, and how much damage it sustained in the hurricane.

In the example below, a Landsat Thematic Mapper (TM) image is used in conjunction

with a shapefile. The shapefile identifies the forest boundary. Within the shapefile, you

can see detailed tree-stand inventory and management information.

This example shows land cover summary statistics for individual land parcels within an arearepresented by a shapefile.


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Identify and monitor urban growth and changes

Cities grow over time. Images give a good sense of how they grow, and how remaining

land can be preserved by managing that growth. You can use the ArcView ImageAnalysis extension to reveal patterns of urban growth over time.

In this example, Landsat data spanning 21 years was analyzed for urban growth. This view

shows the differences in the extent of urban land use and cover between 1973 and 1994.

Those differences are represented as classes. You can see the yellow urban areas in 1994

have grown beyond the red urban areas of 1973.

This view shows the extent of urban area in 1973 (depicted in red) increased over 21 years. Theexpansion is depicted in yellow.

Extract features automatically

Suppose you are responsible for mapping the extent of an oil spill as part of a rapid

response effort. You can use radar data and ArcView Image Analysis extension tools to

identify and map the extent of such environmental hazards.


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In the example below, an oil spill off the northern coast of Spain is colored in blue with

the automated feature mapping capability in the ArcView Image Analysis extension. This

helps you isolate the exact extent of the spill and get information about the area the spill

covers.

In this example, the precise boundary and extent of the oil spill are automatically created in only a fewseconds.

Assess vegetation stress

Crops experience different stresses throughout the growing season. You can use

multispectral imagery and analysis tools to identify and monitor a crops health.

In this example, the Vegetative Index was used to see crop stress. The stressed areas were

then automatically digitized and saved as a shapefile. This kind of information can be used


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to help identify sources of variability in growth patterns. Then you can quickly update

crop management plans.

In this example, areas of crop stress have been identified using Vegetative Index and saved as ashapefile.

Tips on learning the ArcView Image Analysis extension

The more you know about ArcView GIS, the better prepared you are to use the ArcView

Image Analysis extension. Otherwise, you need only have limited knowledge of image

analysis and remote sensing applications. The examples included in this book are

supplemented with technical information to assist you. If you are unfamiliar with the

software, you should refer to Using ArcView GISto familiarize yourself with the

ArcView GIS user interface, functions, and tools, and work through the Quick start

tutorial.

What to read next

A good place to start learning about what you can do with the ArcView Image Analysis

extension is to read Chapter 2, Quick start tutorial, of this book. The chapter gives you a

brief overview of the types of analyses you can perform using the ArcView Image

Analysis extension. You can also learn basic steps and techniques to process an imageusing the ArcView Image Analysis extension.


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How to get on-line help

You can use ArcView GIS on-line help to get information about various components of

the ArcView Image Analysis extension including button, tool, and menu functions;

dialog boxes; and an index of the complete on-line help.

To find out what a button, tool, or menu choice does

Move the cursor over it, but do not select it. A short description appears in the status

bar.

To get help about a button, tool, or menu choice

1. Click the Help button .

2. Click the button, tool, or menu choice you want to get help about.

To get help about a dialog box

Press the F1 key on your keyboard when the dialog is displayed. Some of the more

complex dialogs also provide a Help button equivalent to the F1 key.

To browse the contents of the ArcView GIS help

1. From the Help menu, choose Help Topics.

2. Click the Contents tab.

To search the index of the ArcView GIS help1. From the Help menu, choose Help Topics.

2. Click the Index tab.

To search the ArcView GIS help for a particular word

1. From the Help menu, choose Help Topics.

2. Click the Find tab.

Getting technical support from ESRI and ERDAS

If you are located in the United States, contact Environmental Systems Research

Institute, Inc. (ESRI), for technical support at 909-793-3774 or ERDAS, Inc. at

404-248-9777.


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If you are a customer located outside of the United States, contact your ERDAS

distributor or ERDAS at 404-248-9777. For more information about technical support,

please refer to the Customer Support documents included in your ArcView Image

Analysis software box.

The product registration and support cards that come with ArcView GIS and the

Obtaining technical support section of the ArcView GIS on-line help provide further

information.

Visit ESRI and ERDAS on the web

For more information on ESRIsoftware and services, visit ESRIs web home page at

www.esri.com. For more information on ERDAS products and services, visit the ERDAS

web site at www.erdas.com.

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