GIS Remote Sensing and Imagery 2

Question 1

Which type of satellite orbit provides continuous coverage of the same area on Earth's surface?

Accepted Answer

Geostationary orbit

Answer

Geostationary satellites orbit at ~35,786 km and remain fixed over one point on Earth, enabling continuous monitoring.

Question 2

What does the term 'radiometric resolution' refer to in remote sensing imagery?

Accepted Answer

The number of distinct brightness levels a sensor can detect

Answer

Radiometric resolution describes the number of discrete signal levels (e.g., 8-bit = 256 levels) a sensor can distinguish.

Question 3

In thermal infrared remote sensing, what property of objects is primarily being measured?

Accepted Answer

Emitted heat energy

Answer

Thermal infrared sensors detect heat emitted by objects based on their temperature, not reflected sunlight.

Question 4

Which preprocessing step corrects for differences in sun angle and Earth-Sun distance across an image?

Accepted Answer

Radiometric normalization

Answer

Radiometric normalization adjusts pixel values to account for varying illumination conditions including sun elevation and Earth-Sun distance.

Question 5

What is 'speckling' in SAR imagery and how is it typically reduced?

Accepted Answer

Salt-and-pepper noise from coherent radar interference, reduced by filtering

Answer

Speckle is granular noise inherent to SAR caused by coherent interference of radar waves, commonly reduced with Lee, Frost, or Gamma-MAP filters.

GIS - Geographic Information System Practice Test