Satellite Digital Image Processing
Document Updated: November 2007 Software Version: ERDAS Imagine 9.1
Exercise Objective • To familiarize yourself with the basics of ERDAS Imagine.
Required Data • wforig.img —A 30-meter, raw Landsat TM scene of Salt Lake City, UT and the Wasatch Mountains Introduction Before you start processing imagery, it wouldbe wise to learn a few of the basics that can improve your understanding of and efficiency using ERDAS Imagine. The goal of this exercise to introduce you to ERDAS Imagine and to help familiarize you with the basics. The major steps are: I. Create your Class Data Directory Structure II. Set Preferences III. Display a Single Image Band IV. Display a Multispectral Image I. Create your Class DataDirectory Structure File management is far more important than the emphasis that is usually put on it--it is very easy to lose track of files in an image-processing project. Fortunately, if you make an effort to manage your files, you have the tools to keep everything well organized. In the Windows computing environment, Windows Explorer is the most common tool for file and directory management. Inaddition, ERDAS Imagine has preferences you set to specify default input and output directories. Being familiar with these simple techniques will not assure you of maintaining a reasonable hold on your data but being unfamiliar with them will assure that your data is not being maintained appropriately. Start Windows Explorer and create the folder \erdas_data ( is the hard drive of your choice withat least 200 Mbytes of free space). This will be the location where you will download and access your data for this course. You have any number of options for organizing your data below this directory level—one suggestion is to create a subdirectory for each exercise (e.g., \erdas_data\exer01\) and then download the corresponding exercise data into that subdirectory. Note: You will go through asimilar process with each subsequent exercise—it will be up to you to manage your data: create the appropriate folders, download and decompress the data, and keep track of your files. This is part of the project realism. Also—Some of the dialog boxes we provide in the exercises may have been used from previous versions
Introduction to ERDAS Imagine 1
Introduction to ERDAS Imagine
ofImagine. Do not be alarmed if dialog boxes in these exercises do not resemble exactly what you see on your screen.
These preference settings control where Imagine looks for image files and where your new output files will be written. You will usually want to change this setting with each new project you begin. Pyramid Layers are used by the Viewer to dramatically improve image display speed. It’susually preferable to include the Pyramid Layers file internal to the image file so it is always available. We’ll use the Classic Viewer but you might like the Geospatial Light Table—it provides an enhanced user interface and image windows for viewing and adjusting multiple images simultaneously. You can also set this option to Always Ask and Imagine will prompt you for which type of Viewer you wantto use each time you start a new Viewer.
II. Set Preferences
Imagine’s Preference Editor will allow you to set working and data directories in addition to a great number of other program customization options. In this exercise, you will set a default data directory (where Imagine will look to open data sets); a default output directory (where Imagine will write your output files); and set thedefault band combination for a 3 band image. 1. Start Imagine. From the Windows Taskbar, click Start | Programs | Leica Geosystems | ERDAS Imagine 9.1 | ERDAS Imagine 9.1. 2. From Imagine’s main menu, click Session | Preferences. 3. From the Category list, ensure that User Interface & Session is selected. 4. Set the Default Data Directory to (e.g., D:\SDIP\Basic\Data—this is the directory that...