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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
PARTICULAR PURPOSE. ERDAS, ESRI, AND EACH DATA VENDOR SHALL ASSUME NO
LIABILITY FOR INDIRECT, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES, EVEN
IF ADVISED OF THE POSSIBILITY THEREOF.
RESTRICTED/LIMITED RIGHTS LEGEND
Any software, documentation, and/or data delivered hereunder is subject to the terms of the LicenseAgreement. In no event shall the Government acquire greater than RESTRICTED/LIMITED RIGHTS.
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.