Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial...
Transcript of Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial...
![Page 1: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/1.jpg)
1
Spatial Resolution and Satellite Scene Swath
Beth Goralski
Geog 581
What is Resolution??
![Page 2: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/2.jpg)
2
Resolution Criteria
1. Based on the geometrical properties of the system
2. Ability to distinguish between points3. Ability to measure the periodicity of
repetitive targets4. Ability to measure the spectral
properties of small targets
Resolution is…
1st Criterion
Geometry
![Page 3: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/3.jpg)
3
Instantaneous Field of ViewInstantaneous Field of View• IFOV= The area on the
ground that is viewed by the instrument from a given altitude at any time.
HD
=α
H
D
Proof of IFOV Geometry
)2
(tan 1
ab−=θ
ab
=θtan2
0→θD
aD
=θ
ab2
=θ2b=D
H = a = altitudeHD
=θ
θ
![Page 4: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/4.jpg)
4
IFOV
2nd Criterion
Point Sources
![Page 5: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/5.jpg)
5
2 Dimensional Plot of the Point Spread Function
1.0
0.5
Point Spread Function (3D)
![Page 6: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/6.jpg)
6
Resolving Point Sources
Diffraction Pattern
![Page 7: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/7.jpg)
7
Rayleigh’s Criterion
λ
dRλθ 22.1=
= wavelength
d = diameter of circular aperture opening
IFOV deficiencies
• Based solely upon geometry and neglects spectral properties of the target
• Point sources are difficult to distinguish
![Page 8: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/8.jpg)
8
ERE
• Effective Resolution Element— ”the size of an area for which a single radiance value can be assigned with reasonable assurance that the response is within 5% of the value representing the actual relative radiance”.
Modulation• The ratio of maximum and minimum
radiance values recorded over a given area.
minmax
minmax
EEEEM
+−
=
![Page 9: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/9.jpg)
9
Pixels
• A digital image is an ordered set of numeric values and is not necessarily related to IFOV.
• Pixels are more than an average of reflected radiance.
IFOV for AVHRR
http://www2.ncdc.noaa.gov/docs/podug/html/c3/sec3-0.htm
![Page 10: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/10.jpg)
10
Definition of Radian
Ground Swath for AVHRR
The IFOV for the AVHRR is 1.4 mrad, its altitude is 833 km.
Solve for D using the equation:
1.4 mrad = D/833 km0.0014 rad = D/833 kmD = 1.1 km
HD
=α
α
![Page 11: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/11.jpg)
11
3rd Criterion
Periodicity
Period of a Satellite
20
')'(2
pgR
HRHRT p
p
++= π
T0= orbital period, sec.
Rp= planet radius, km (6380km for earth)
H’= orbital altitude, km
gs = acceleration due to gravity (9.81m/s2)
![Page 12: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/12.jpg)
12
Orbital Period for AVHRR
• T0=2π(6380+833)√[(6380+833)/(0.0098*63802)]
• T0 = 6091.1sec• T0= 1.7hr
• Therefore, The AVHRR orbits earth ~14.1 times per day.
Comparison of Satellite Sampling Resolutions
http://landsathandbook.gsfc.nasa.gov/handbook/handbook_htmls/chapter6/chapter6.html
![Page 13: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/13.jpg)
13
http://landsathandbook.gsfc.nasa.gov/handbook/handbook_htmls/chapter6/chapter6.html
Ground Swath
http://landsathandbook.gsfc.nasa.gov/handbook/handbook_htmls/chapter6/chapter6.html
![Page 14: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/14.jpg)
14
Satellite Sensors
A: Rotating MirrorB: DetectorsC: Instantaneous Field of ViewD: Ground Resolution CellE: Angular Field of ViewF: Swath
Across Track Scanner
A: Linear Array of DetectorsB: Focal Plane of ImageC: LenseD: Ground Resolution Cell Advantages over across track- no moving parts- finer spatial resolution- finer spectral resolution- better signal/noise ratio- simplifies image construction
Along Track Scanner
• But for our purposes, spatial resolution is:
A measure of the smallest angular or linear separation between two objects usually expressed in radians or meters.
Spatial resolution depends upon your purposes.
![Page 15: Spatial Resolution and Satellite Scene Swathweb.pdx.edu/~jduh/courses/Archive/geog481w07/...Spatial Resolution and Satellite Scene Swath Beth Goralski Geog 581 What is Resolution??](https://reader034.fdocuments.us/reader034/viewer/2022042123/5e9e3b6675df4b630f31b5ba/html5/thumbnails/15.jpg)
15
Ground Swath