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Fundamentals of Remote Sensing: Digital Image Analysis. Advanced Remote Sensing: Introduction to Digital Image Analysis. Lecture 1 Prepared by R. Lathrop 10/99 updated 9/03 Readings: ERDAS Field Guide 5th ed ERDAS CH. 1: 1-15; 3: 52-77. Lecture Notes 1: Overview of Remote Sensing .

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advanced remote sensing introduction to digital image analysis

Advanced Remote Sensing: Introduction to Digital Image Analysis

Lecture 1

Prepared by R. Lathrop 10/99

updated 9/03

Readings:

ERDAS Field Guide 5th ed

ERDAS CH. 1: 1-15; 3: 52-77

slide3

Lecture Notes 1: Overview of Remote Sensing

A number of these slides were originally produced by Scott Madry and Chuck Colvard with some subsequent modification by Rick Lathrop. Additional slides were produced by Rick Lathrop.

remote sensing
“Remote sensing is the science and art of obtaining information about an object, area, or phenomenon through the analysis of data acquired by a device that is not in contact with the object, area, or phenomenon under investigation”.-Lillesand & Kiefer (1987)Remote Sensing
radiation source target sensor
Radiation source/target/sensor

Electromagnetic energy interacts with physical matter in different ways in different parts of the spectrum.

Some energy is scattered, absorbed, etc.

digital image acquisition analysis
Digitization of analog aerial photography, can be very useful for historical studies and/or for high spatial resolution needs

Direct acquisition using some form of digital imaging sensor

Computerized image analysis can help to enhance and extract information content of imagery in a time-efficient, cost-effective manner

Computers still can not replace the human image analyst

Digital Image Acquisition & Analysis
aerial cameras
Aerial Cameras

Keystone’s Wild RC-10 mapping camera

A large format oblique camera

aerial photos
Black & White - single panchromatic layer

Color: 3 layers B-G-R

Color IR: 3 layers G-R-NIR

Aerial photos
aerial photos9
The traditional form of remote sensing

Pro:

Can be easily customized to meet specific requirements

Con:

Can be expensive

Need access to plane

Time consuming interpretation

Repeat coverage often infrequent

Different sun angles

Aerial photos
space borne remote sensing
Space-borne Remote Sensing
  • Emerging Technology
  • Pro:
  • GIS ready
  • faster turn around
  • acquisition time of 5 minutes gives equal solar illumination, shadows, no clouds
  • easy to repeat for change detection
  • Con:
  • Significant investment in computer hardware/software
  • Less flexibility in acquisition
passive electro optical systems
Electronic sensors can acquire data outside the visible spectrum

Elements sensitive to electro magnetic energy (EME) of certain wavelengths focus energy onto a sensor plane. A prism is used to divide the energy into specific wavelengths. The CCD’s are stimulated and produce an electrical signal equal to the energy focused upon it. These data are recorded.

Data are processed and displayed on computers-images are composed of “pixels”, whose brightness relates to the strength of the radiation received from an area on the surface.

Digital processing of the data produces useful information

Passive electro-optical systems
design of a remote sensing effort
Clear definition of the problem

Evaluation of the potential of remote sensing techniques

Identification of appropriate remote sensing data acquisition procedures

Determination of the data interpretation procedures

Identification of the criteria by which the quality of information can be evaluated

Design of A Remote Sensing Effort
resolution
Four kinds of resolution determined by user needs:

Spatial Resolution: How small an object do you need to see (pixel size) and how large an area do you need to cover (swath width)

Spectral Resolution: What part of the spectrum do you want to measure

Radiometric Resolution: How finely do you need to quantify the data

Temporal Resolution: How often do you need to look

Resolution
spatial resolution
Spatial resolution

Instantaneous Field of View (IFOV)

determines the dimension, D,

of the Ground Resolution Cell

(GRC) imaged on the ground

IFOV

swath width
Landsat-185km (100 mi)

80 m = 40 Mb-4 bands (MSS)

30 m = 320 Mb-6 bands (TM)

10 m = 342.25 Mb-1band

5 m = 1.369 Gb -1 band

1 m = 34.225 Tb - 1 band

How small do we need?

How much data can we store and process?

Swath width

185 by 185 km

the electromagnetic spectrum
The electromagnetic spectrum

Comparative Sizes: from subatomic to human scales

Atom Nucleus

Molecule

Human & larger

Pinhead

Atom

Bacteria

Honeybee

From NY Times graphic 4/8/2003

landsat tm 7 bands 8 bit data
Landsat TM-7 bands-8 bit data

Spectral

(where we look)

Radiometric

(how finely can we

measure the return)

0-63, 0-255, 0-1023

Landsat TM BAND 1 2 3 4 5 7 6

radiometric resolution
Radiometric resolution
  • Sensitivity of the detector to differences in EMR signal strength determines the smallest difference in brightness value that can be distinguished

Bright

Dark

Determined by the A-to-D quantization

6 bit = 0-63, 8 bit = 0-255, 10 bit = 0-1023

radiometric resolution26
Radiometric resolution
  • Higher radiometric resolution is especially important for quantitative applications such as sea-surface temperature mapping where the user wants to distinguish small differences in temperature
satellite remote sensing orbits give repeat coverage
Geostationary Polar Sun-synchronous

Constant view of hemisphere Covers entire Earth

Satellite remote sensing orbits give repeat coverage

700-900 km

35,800 km

change detection
The ability to monitor change is one of the benefits of remote sensing

We can monitor human and natural changes in the landscape

Change Detection
spatial and temporal resolution
Spatial and temporal resolution

Ground Surveys

50 years

As spatial resolution

increases, the revisit

time is also increased, as are the applications that are appropriate and the cost

Aerial Photography

5 years

Repeat

time

Space photography

3 years

SPOT

28 days

Landsat-TM

17 days

NOAA AVHRR

12 hours

Meteosats

30 min.

.1 m 1 m 5 m 10-20m 30m 1 km 5 km

Ground resolution

slide33

Different sensors and resolutions

sensor spatial spectral radiometric temporal

----------------------------------------------------------------------------------------------------------------

AVHRR 1.1 and 4 KM 4 or 5 bands 10 bit 12 hours

2400 Km .58-.68, .725-1.1, 3.55-3.93 (0-1023) (1 day, 1 night)

10.3-11.3, 11.5-12.5 (micrometers)

Landsat MSS80 meters 4 bands 6 bit 16 days

185 Km .5-.6, .6-.7, .7-.8, .8-1.1 (0-63)

Landsat TM30 meters 7 bands 8 bit 14 days

185 Km .45-.52, .52-.6, .63-.69, (0-255)

.76-.9, 1.55-1.75,

10.4-12.5, 2.08-2.3 um

SPOT 10m P / 20m X P -1 band X- 3 bands 8 bit 26 days

60 Km P - .51-.73 um (0-255) (2 out of 5)

X - .5-.59, .61-.68, .79-.89 um

IRS1 5.8 meters 1 band 6 bit 22 days

70 km .5-.75 (0-63)

IKONOS 1 meter 1 band 8 bit 3 days

11 km .45-.9 (0-255) (1.5 out of 3)

slide34
Remote sensing : acquiring and analyzing data using distant devices recording electromagnetic energy

• Digital scanning devices or analog photography

• Airborne, terrestrial, marine, or orbiting platforms

• Can be passive, sensing existing radiation, or active, sensing radiation bounced off the surface, as with radar.

Remote sensing usually involves digital data, but also photography

Usually means both the capture and computerized image analysis of data. Quantitative, easily incorporated into GIS

• Design of a remote sensing effort must clearly define information needs and consider the 4 types of remote sensing resolution: radiometric, spatial, spectral, temporal when considering the types of imagery to use

Remote Sensing - Summary