Remote Sensing and GNSS Quiz

A satellite sensor captures an image with a spatial resolution of 30 meters. What is the minimum size of an object that can be detected by the sensor?

• 15 meters

• 30 meters

• 60 meters

• 120 meters

Calculate the radiometric resolution if a sensor records data in 8 bits.

• 64 levels

• 128 levels

• 256 levels

• 512 levels

If the revisit time of a satellite is 16 days, how many images of the same area can be captured in a year?

• 23 images

• 26 images

• 21 images

• 16 images

What is the difference between reflectance and radiance in the context of remote sensing?

• Reflectance measures light leaving a surface, while radiance measures energy per unit area.

• Reflectance is the fraction of light reflected, radiance is energy reflected from an object.

• Reflectance is energy emitted by the sun, radiance is energy reflected from Earth's surface.

• Reflectance measures total light emitted, radiance measures atmospheric energy.

If the spectral resolution of a sensor is 10 nm, how many bands can be detected between 400 nm and 1000 nm?

• 50 bands

• 60 bands

• 70 bands

• 80 bands

Calculate the ground resolution if a satellite sensor with a focal length of 1 m and a detector size of 20 µm operates at a height of 600 km.

• 12 meters

• 30 meters

• 24 meters

• 36 meters

For a sensor operating in the thermal infrared region (8-14 µm), why are thermal data more influenced by surface emissivity than by reflectance?

• Emissivity determines the amount of heat emitted.

• Emissivity varies based on the angle of the sun.

• Thermal sensors detect visible light only.

• Reflectance is influenced by atmospheric scattering.

Explain the significance of atmospheric window regions in remote sensing.

• They allow transmission of specific wavelengths with minimal absorption by the atmosphere.

• They determine how much energy the atmosphere emits.

• They are areas with less radiation interference from the sun.

• They allow sensors to capture more spectral bands.

Given that Landsat 8 has a temporal resolution of 16 days, what are the advantages and disadvantages for change detection studies?

• Advantage: Detects fast changes; Disadvantage: Long revisit time.

• Advantage: High spatial resolution; Disadvantage: Low spectral resolution.

• Advantage: Covers a large area; Disadvantage: May miss rapid changes.

• Advantage: Short revisit time; Disadvantage: Poor data quality.

How does increasing the spectral resolution of a sensor affect its ability to detect subtle material differences on Earth's surface?

• Increases ability to detect subtle material differences.

• Decreases ability due to less detailed data.

• Has no impact on material detection.

• Reduces spatial resolution but improves detection of small features.