Remote Sensing Part 3: Image and Resolution

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Questions and Answers

Which property of a pixel defines its intensity of spectral response in a particular band?

Radiometric property

Spatial property

Spectral property (correct)

Temporal property

What does spatial resolution primarily refer to in remote sensing?

The frequency of time a location is observed

The size of the area that can be observed at one time

The range of wavelengths used in imaging

The smallest discernible features in an image (correct)

What is the Instantaneous Field of View (IFOV)?

The wavelength range utilized by the sensor

The spatial resolution limit of a sensor

The angle extended by a single detector on the sensor (correct)

The total area captured in a single image

Which factor does NOT affect spatial resolution?

Color of the target Signup and view all the answers

If a sensor has a longer focal length, what is the expected outcome regarding its field of view?

Smaller field of view Signup and view all the answers

Which resolution defines how often a particular area is observed?

Temporal Resolution Signup and view all the answers

Which of the following factors is most likely to increase spatial resolution?

Smaller pixel size Signup and view all the answers

Which resolution is focused on the degree of detail observed in the image?

Radiometric Resolution Signup and view all the answers

What is the effect of a narrow spectral bandwidth on spectral resolution?

Reduces spectral resolution and energy detection Signup and view all the answers

Which of the following combinations ensures both good spatial and radiometric resolution?

Wide spectral bands with good spatial resolution Signup and view all the answers

What is necessary for effective differentiation of signal from noise?

High signal-to-noise ratio Signup and view all the answers

Which type of composite image is created using the three primary colors of red, green, and blue?

True color composite Signup and view all the answers

What results from a fine spatial resolution in regards to energy detection?

Less energy detection and poor radiometric resolution Signup and view all the answers

What is a characteristic of multispectral images?

Composed of multiple rows and columns of pixels across spectral bands Signup and view all the answers

How does poor spectral resolution affect energy detection?

Reduces the ability to detect fine energy differences Signup and view all the answers

What type of sensor typically detects light reflectance in multiple bands of the electromagnetic spectrum?

Multispectral sensor Signup and view all the answers

What does a smaller scale fraction, such as 1:50,000, indicate about the representation of objects in an image?

Objects are represented over larger areas. Signup and view all the answers

How is Ground Sample Distance (GSD) related to flight height?

Higher flight altitude results in a larger GSD. Signup and view all the answers

Which of the following best describes detectability in spatial resolution?

The ability to discern the absence or presence of an object. Signup and view all the answers

In aerial photography, if an image has a scale of 1:15,000, how long would a bridge measuring 0.25 inches in the photograph be in reality, in feet?

25 feet Signup and view all the answers

What is a characteristic of a digital image compared to a photographic image?

It has a variable Ground Sample Distance. Signup and view all the answers

What does the term spectral resolution refer to in a satellite imaging system?

The width of spectral bands detectable. Signup and view all the answers

The ability to identify objects such as distinguishing cars from trucks in an image is referred to as which of the following?

Identification Signup and view all the answers

Which of the following represents a limitation of a photographic image in terms of resolution?

It cannot be resampled for higher resolution. Signup and view all the answers

What does spectral resolution refer to in satellite imaging systems?

The width of the bands in which the system can detect data Signup and view all the answers

Which factor does NOT influence temporal resolution in a satellite imaging system?

Electricity supply of the satellite Signup and view all the answers

What describes the relationship between radiometric resolution and the number of digital levels?

Greater radiometric resolution corresponds to more digital levels Signup and view all the answers

If an image has a radiometric resolution of 8 bits, what is the maximum value of the digital number that can be represented?

255 Signup and view all the answers

How does finer radiometric resolution affect an imaging system's performance?

It enhances the system's sensitivity to energy differences Signup and view all the answers

What is the computed number of values for a digital image with a radiometric resolution of 6 bits?

64 Signup and view all the answers

Which of the following does not contribute to the temporal resolution of satellite data?

Satellite's manufacturing material Signup and view all the answers

Which statement is true regarding multi-spectral satellite imaging systems?

They are designed to detect multiple discrete bands Signup and view all the answers

What is a key characteristic of hyperspectral sensors?

They typically record more than 100 narrow, contiguous spectral bands. Signup and view all the answers

When creating a natural composite image using the SPOT HRV scanner, which bands are combined for the color representation?

Green, red, and NIR bands. Signup and view all the answers

What type of applications can benefit from hyperspectral image interpretation?

Various applications including geological and environmental. Signup and view all the answers

Which of the following is NOT a primary application of hyperspectral sensors?

Cooking temperature assessment. Signup and view all the answers

What type of information does the spectral library provide in hyperspectral image interpretation?

Targets' spectra for comparison. Signup and view all the answers

Which process helps identify targets based on pixel spectra in hyperspectral imaging?

Marking spectra that match a target with high confidence. Signup and view all the answers

Which application area includes monitoring glacier dynamics?

Hydrological applications. Signup and view all the answers

Which type of mapping is involved in natural resource management?

Sand and gravel exploration. Signup and view all the answers

What does a composite curve indicate in hyperspectral imaging?

A mix of multiple feature classes. Signup and view all the answers

Which of the following is a primary benefit of using a natural composite image?

It enhances the differentiation of ground features. Signup and view all the answers

Study Notes

Nature of the Image

Pixel: Basic unit in imaging with spatial and spectral properties.
Spatial Property: Represents the height and width of ground features.
Spectral Property: Indicates intensity of spectral response in a specific band.
Sample Components:
- Buildings: 15% coverage, 90% reflectance.
- Sand: 15% coverage, 100% reflectance.
- Trees: 50% coverage, 50% reflectance.
- Water: 20% coverage, 10% reflectance.

Image Resolution Types

Spatial Resolution: Defines the smallest detail visible in an image; high resolution allows for discernible small features.
Spectral Resolution: Refers to the wavelength range detected by the sensor; narrower bands enhance resolution.
Radiometric Resolution: Measures the sensor's detail observation capability; more levels allow for finer detail.
Temporal Resolution: Indicates observation frequency depending on satellite orbit, target latitude, and sensor swath width.

Spatial Resolution

Coarser resolutions obscure small features, while finer resolutions reveal them.
Influencing Factors: Atmosphere, haze, smoke, sensor clarity, pixel size, and Instantaneous Field of View (IFOV).
IFOV: Angle of visibility for sensor detection, affecting spatial resolution.
Shorter focal lengths yield wider fields of view; longer lengths provide smaller footprints.

Image Scale

Scale represents the distance on an image versus the corresponding ground distance.
Large scale (e.g., 1:50,000) shows objects clearly; small scale (e.g., 1:250,000) renders objects less discernible.
Ground Sample Distance (GSD): Distance between pixel centers, greater height results in larger GSD and lower resolution.

Interpretability in Spatial Resolution

Detectability: Ability to record an object’s presence even if it's below the operational capacity.
Recognizability: Identifying objects correctly; can be detected but not recognized.
Identification: Distinguishing features such as vehicle types or tree species.

Spectral Resolution

Spectral resolution is determined by bandwidths of detected bands; narrow bands provide greater resolution.
Multispectral sensors record data across multiple bands, combining them to form color images.

Types of Composite Images

True Color Composite: Combines primary color bands (red, green, blue) captured by sensors.
False Color Composite: Uses arbitrary color assignments to identify distinct ground features, especially when primary bands are not available.
Natural Composite Image: Resembles a visual photograph created from available spectral bands.

Hyperspectral Sensors

Capture numerous narrow spectral bands, enabling detailed reflectance spectrum construction.
Typically more than 100 bands recorded, facilitating advanced spectral analyses via imaging spectrometers.

Remote Sensing Applications

Geological: Includes mapping surface deposits, mineral exploration, environmental geology, and hazard mapping.
Hydrological: Encompasses wetland mapping, flood monitoring, and groundwater exploration.
Land-Use: Addresses wildlife habitat protection, urban development, and damage assessment from disasters.
Oceanographic: Involves ocean monitoring, storm forecasting, and oil spill response.

Signal to Noise Ratio

Defined as the ratio of signal power to background noise; high SNR simplifies differentiation between the two.

Balancing Resolutions

Fine spatial resolution typically correlates with small IFOV but may lead to lower energy detection capabilities.
Successful imaging requires a balance between spatial, spectral, and radiometric resolutions tailored to specific objectives.

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Description

This quiz focuses on understanding images in remote sensing, specifically the concepts of pixel spatial and spectral properties. Learn how these properties affect image composition and pixel representation in remote sensing applications.