Exam II

Question 1

What are biophysical variables?

Answer 1

Characteristics a satellite image can sense

Question 2

List direct biophysical variables?

Answer 2

• x, y
• elevation
• color
• biomass
• moisture
• heat

Question 3

List hybrid biophysical variables?

Answer 3

• land cover/ use
• stress
• productivity

Question 4

What is a Geotiff?

Answer 4

A TIFF file that has been geocoded

Question 5

What has better resolution, TM or MSS?

Answer 5

Thematic mapper (TM) has better resolution (16 scan lines) than Multispectral Scanner (MSS) (6)

Question 6

Landsat vs SPOT?

Answer 6

Landsat (whiskbroom scanner):
- MSS, TM
SPOT (pushbroom scanner):
- Pan, HRV

Question 7

Radiometric correction, why?

Answer 7

1. Large area
2. Difference sum angles
3. Extend results to other areas
4. Compare to other data

Question 8

What are detector errors?

Answer 8

Errors that affect the quality of a satellite data set

Question 9

Types of detector errors?

Answer 9

1. Line dropout - one detector fails (Fix: Avg. #s) (Results in failure from Landsat**)
2. Destripping - detector drift

Question 10

What is histogram subtraction?

Answer 10

Adjusting for atmospheric scatter via simple math

- subtract min DN from each band

Question 11

What happens as a result of Raleigh scatter?

Answer 11

DNs increase

Question 12

What is histogram regression?

Answer 12

Adjusting for atmospheric scatter via regression techniques

• No ref. in IR Regions
• Regress pixels in clear deep water and shadows

Question 13

What is geometric correction?

Answer 13

Projecting image data onto a flat plane to conform to a map projection

Question 14

Ways to tell if an image has been geometric corrected?

Answer 14

1. Inquire
2. Measuring tool
3. Check MetaData

Question 15

Geometric correction, step 1?

Answer 15

Locate GCP’s

• pixels found on map and image
• min # of GCP’s = ((t+1)(t+2)/2

Question 16

Geometric correction, step 2?

Answer 16

Create transformation model

• determine RMS error
• RMS -> on avg.
• to decrease RMS error

Question 17

Geometric correction, step 3?

Answer 17

Perform G.C.

• Spatial interpolation
• Spectral interpolation
• Bilinear interpolation (img. -> smooth)
• Cubic convolution

Question 18

Types of geometric correction?

Answer 18

Georeferencing (assigns map coordinates to an img)

Registration (Landsat 5)

Question 19

How do satellites find space?

Answer 19

Telemetry