Digital Image Processing (GHY 4810)

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Nov 6, 2013 (3 years and 5 months ago)

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GISC 7365
:
Remote Sensing Digital Image Processing

Dr. Fang Qiu


L
ab 1: Introduction to ERDAS IMAGINE


In this semester, we will be using ERDAS IMAGINE digital image processing software
for labs and projects. ERDAS (Earth Resource Data Analysis System

-

http://www.erdas.com
.
) is a mapping software company specializing in Geographic
Imaging solutions. Software functions include importing, viewing, altering, and
analyzing raster and vector data sets.


Objective:

Through t
his lab, students should be able to



Know how to login to the computers at Computer Lab



Get familiar with the graphic user interface of ERDAS IMAGINE software.



Know how to set user preference in IMAGINE software.



Display an image using IMAGINE Viewer


Mater
ials:

The images you will be working with for most of the semester are located under directory
T
:

\
Qiu
\
RSDIP
\
Data


1.

Using Computers in the Computer lab.



Login to the computers using your

NetID and

password
. Make sure Domain is
CAMPUS
.



Create a directory
na
mely rsdata under
C:
\
usr
\
your_initial or your H: drive
. You
should put all your data and exercises under this directory.


2.

Introduction to ERDAS IMAGINE.



L
aunch IMAGINE
: Go

to the Start Men
u
-

ALL

Programs


ERDAS

-

Geospatial
Imaging 9.3

-

ERDAS IMAGINE

9.
3
.

E
xamine the
icon panel along the top of the
screen. These icons represent the various components and add
-
on modules purchased
with the system.




To

display the icon panel
v
ertically
on
the left side of the screen
:

Click on Session

and then select Flip
Icons to flip the icon panel.

Try reverting back to horizontal
position.



Familiarize yourself with the five menus located along the top of the icon panel in the
left corner: Session, Main, Tools, Utilities

and

Help. The Session

menu controls

session setti
ngs


such as user preferences and configuration. The Main

menu allows
access to all the modules located along the icon panel. The Tools

menu allows you to
display and edit annotation, image, and vector information,
etc
. The Utilities

menu
allows access to
a variety of compression and conversion algorithms including JPEG

C
ompress
I
mage
,
Convert I
mage to
A
nnotation, and
Convert A
nnotation to
R
aster
,
2


etc
. The Help

menu brings up the On
-
Line documentation as well as icon panel and
version information. An index
of keywords helps you to quickly locate a help topic
by title. A text search function also helps you find topics in which a word or phrase
appears.


3.

Set User Preferences in IMAGINE.


The menu you will probably use the most under the Session

menu is the Pre
ference
Editor. It allows you to customize and control many individual or global IMAGINE
parameters and default settings.



Click on Session and then select Preference
s

to open the Preference Editor.



Select

User
Interface & Session


category

from the Categ
ory window on the left
side
.



L
ocate
the

Default Data Directory


and

Default Output Directory


preferences

on the right side window
.



Set Default Data Directory and Default Output Directory to
T
:
\
Qiu
\
RSDIP
\
Data

and C
:
\
usr
\
<your directory>

or

a folder at yo
ur H: drive
.



Scroll down and l
ocate the Delete Session Log on Exit

and Delete History File on
Exit

preferences.

C
heck
these
to enable those two preferences. Leave all other
options in their default settings.



Click on
User
Save

to save the preference only
for the machine where the
changes were made.



Click on Close to close the Preference Editor dialog.

Exit
ERDAS

Imagine and
Reopen it


4.

Image Display.


The image we are going to display in the Viewer is:







To display the image in the Viewer:

File Name

C
ola_10
-
7
-
97atlas.img


Quick View

Locatio
n

Downtown Columbia, SC


RGB=4,3,2

Altitude 5000 ft AGL

Sensor

Airborne Terrest. Applications

Sensor (ATLAS)

Spatial

3 m x 3 m

Temporal

October 7, 1997

Spectral


Band 1 = Blue (.45
-
.52)

Band 2 = Green (.52
-
.60)

Band 3 = Red (.63
-
.69)

Band 4 = NIR (.76
-
.90)

3




In the Viewer, select
File

-

Open

and then s
elect
Raster

Layer

from the sub
-
menu
.
This will open the
Select Lay
er
s t
o Add

dialog.



Locate the
cola_10
-
7
-
97atlas.img

and select it

by single click BUT
DO NOT
CLICK THE
OK

BUTTON
.



Click on the
Raster Options

tab

at the top of the dialog box
.




Display as: True Color. Set bands to:

Red
-
band 3; Green
-
band 2; Blue
-
band 1.
C
heck
Clear Display
. Check
Fit to Frame
. Then click
OK
.

A natural color composite image of the downtown scene of Columbia will be display in
the Viewer.
To remove an image displayed in the Viewer
, s
elect
File

and then select
Clear
. You can also click on th
e Eraser Icon in the Viewer to remove an image from the
Viewer.



You can also click on the Folder Icon or type Ctrl R

to access the Select Layer To
Add dialog.
Select the same file.



Click on the Raster Options

tab. Display as: True Color, Layers To Color
s
:

Red
-
band 4; Green
-
band 2; Blue
-
band 1. Check Clear Display. Check Fit to Frame.
Then click OK.



A

NIR false color composite image of the downtown Columbia will be displayed
in the Viewer.

Click
Interactive
Zoom In Icon to magnify the image. The area
over w
hich you place the cursor will be the general center for the area that is
magnified.



Click Zoom Out Icon to reduce the image. Click Pan Icon to pan the image in the
Viewer. Right click on the view and select
Fit
Image
to Window
.




You can
s
ave the view of t
he current image to a
n

.img
file
by selecting
File



View to Image
.



Additional Viewers may be opened by clicking the Viewer icon on the
IMAGINE icon panel.

F
ollow the directions listed below for ending an IMAGINE session.



Click Session and then select Cl
ose All Viewers.



Click Session and then select
Exit IMAGINE
.



Do not print the Log Files
.



Home Work



Display the
Downtown Columbia
image
in gray scale using the
Layer 4
.



Fit Image to Window

and
Convert your view into
an

.img file and turn it in the
drop

box.


5.

Zoom in/out, pan, scale, rotate and magnify an Image.


In EDRAS IMAGINE there are four different ways to zoom in and out of an image
:
Zooming the image by any factor
,
Animated zoom
,
Box zoom
, and R
eal
-
time zoom


The multispectral image for this ex
ercise is:

4



















Start EDRAS. In Viewer #1, Display
charleston_12
-
8
-
90tm.img
as True Color.
Red
-
4; Green
-
3; Blue
-
2. You are now looking at a NIR false
-
color composite of
TM Ba
nds 4, 3, 2 (R, G, B).



Select View


Zoom and see the various choices under Zoom submenu



You can zoom in/out by a factor of 2 or you can also zoom in/out by any factor
you specify. Experiment with them.



You can also quickly Zoom the image in/out by a fac
tor of 2 by clicking the quick
zoom icon from the
Viewer

toolbar.



Animated zoom
:



Click on the animated zoom icon

(i.e. Interative Zoom In/Out)

from the toolbar
and then click on the image.



Try clicking on different areas of the image like top l
eft or lower right.



Draw a box using the left mouse button (lmb) to zoom in/out to a specific area



Another type of zooming is the Real
-
time zoom.With the animated zoom icon
selected hold down the middle mouse button (mmb) and drag the mouse. For two
butto
n mouse, hold the control key and left mouse button and drag.



Now click
Roam/Rotate Image

Icon to pan
and rot
at
e
the image in the Viewer

by
using the left and middle mouse button
.


File Name

charleston_12
-
8
-
90tm.img

Quick View

Location

Charleston, SC


RGB=1,2,4

Altitude 705 km

Sensor


Landsat TM

Spatial

30 m x 30 m

Temporal

December 8, 1990

Spectral

Band 1 = Blue (0.45
-
.52)

Band 2 = Green (.52
-
.6
0)

Band 3 = Red (.63
-
.69)

Band 4 = NIR (.76
-
.90)

Band 5 = MIR (1.55
-
1.75)

5


Scaling an Image:



Select View
-

Scale and examine the submenu



Image To Wind
ow
: Select this option to resize the image to the viewer size.



Window To Image
:Select this option to resize the viewer to the image size.



You can also access these two menu by right
-
clicking on the image.



Extent
: Select this option to define the area of t
he image to view. The View
Extent dialog is opened.

o

ULX: Enter the upper left X coordinate of the portion of the image you
want to view.

o

ULY: Enter the upper left Y coordinate of the portion of the image you
want to view.

o

LRX: Enter the lower right X coor
dinate of the portion of the image you
want to view.

o

LRY: Enter the lower right Y coordinate of the portion of the image you
want to view.


Scale Tool:



Select this option to change the scale of the displayed image. The Frame Scale
dialog is opened wi
th the current scale as default. Change the scale factor by half
and Apply.

Rotating an image:



Select View
-

rotate and enter a rotation value in degrees.



Select View
-
Zoom
-
Rotate and Magnify. How does this work? Experiment.



Click Reset Zoom Icon (with a mag
nifying
lens

inside a red circle) to restore the
Image original orientation.

Magnifying an image:



Select
View | Create Magnifier
from the Viewer menu bar.



A rectangular box called area of interest (AOI). This area is displayed in a small
magnifier window
that opens over the top corner of the Viewer.



Put mouse in the center of the AOI box and drag the box to move the AOI box
around. See what happens in the magnifier window.



Hold with lmb at the corner of the AOI box and resize it and see what happens in
the

magnifier window. Resize the magnifier window to see what happens to the
AOI box in the Viewer. What is the relationship between the AOI box and the
magnifier window?



Select File and then Close Other Viewers to close the magnifier window.



Click the Eraser

Icon to remove the image from the Viewer.


Homework



Rotate the image 45 degrees clockwise and
change the
scale
to
1:150000.
Capture
the image by clicking the title bar of the Viewer window, and pressing both Alt
and Print Screen keys. S
ave it inside a .do
c file to
put it in the dropbox.

6



6.

Image Overlay



File Name

cola_1
-
15
-
91tm.img


Quick View

Location

Columbia, SC


RGB=4,3,2

Altitude 705 km

Sensor

Land
sat TM

Spatial

30 m x 30 m

Temporal

January 15, 1991

Spectral


Band 1 = Green (.52
-
.60)

Band 2 = Red (.63
-
.69)

Band 3 = NIR (.76
-
.90)





















Images from different remote sensing systems can be overlaid with each other if the
images cover the same region of the Earth. In this part of the exercise, we will overlay a
high resolution ATL
AS image on top of the TM image of Columbia, SC. The TM and
ATLAS images we will use are given above.




Open the Landsat TM image of Columbia, SC (i.e.,
cola_1
-
15
-
91tm.img)
.
as: True
Color, Layers To Color: Red
-
3; Green
-
2; Blue
-
1,



Open the ATLAS image of C
olumbia, SC (i.e.,
cola_10
-
7
-
97atlas.img)
.
as: True
Color, Layers To Color: Red
-
4; Green
-
3; Blue
-
2,
uncheck

Clear Display, check Fit to
Name

cola_10
-
7
-
97atlas.img


Quick View

Location

Columbia, SC


RGB=4,3,2

Altitude 5000 ft AGL

Sensor

Airborne Terrest. Applications

Sensor (ATLAS)

Spatial

3 m x 3 m

Temporal

October 7, 1997

Spectral

Band 1 = Blue (.45
-
.52)

Band 2 = Green (.52
-
.60)

Band 3 =

Red (.63
-
.69)

Band 4 = NIR (.76
-
.90)

7


Frame. Then click on OK. You are now overlaying a higher resolution (3m x 3m)
ATLAS image on top of the TM image.



Zoom

into the downtown area and experiment with the utilities and answer the
following questions.



Play with the Blend, Swipe and Flicker tools under Utility menu and briefly discuss
how the following utilities could be useful for an image analyst:

a.

Utility


Bl
end

b.

Utility


Swipe

c.

Utility


Flicker


Homework:



A natural color composite of the downtown scene
(i.e. cola_10
-
7
-
97atlas.img)
can be
viewed by selecting Raster, and then Band Combinations. Change Layers To Color
to: Red
-
3; Green
-
2; Bule
-
1. This is the way
human would view the scene if looking
down from a plane.



The ATLAS image is on top of the TM image in the Viewer. To bring the TM image
to the top of the Viewer. Click on View and then select Arrange Layers. In the
Arrange Layers dialog, drag the
cola_1
-
15
-
91tm.img
box to the top of
cola_10
-
7
-
97atlas.img
. Click Apply in the Arrange Layers dialog to redisplay the layers in their
new order in the Viewer. The layers are now reversed.
Use Swipe Tool to display
both image at 50% horizontally
.
Click the title ba
r of the view window, then
press

Alt
+
Print Screen

key

to copy the image
.
Paste and s
ave it inside a .doc file and turn it
into the dropbox.