Remote Sensing Flashcards
What is remote sensing?
Capturing information about objects on the earths surface based on measurement of electromagnetic energy reflected or emitted from those objects
How does remote sensing capture data?
By using specialized platforms and sensors from various heights
What was the Landsat program?
The first Earth-observing satellite to be launched with the express intent to study and monitor the planet’s landmasses.
What is electromagnetic spectrum?
A range of short wavelengths (gamma, x-ray) to long wavelengths (microwaves, radio waves)
What 3 ways does the sun’s incident radiation interact with the earths surface? What does it depend on?
Transmission, Absorption, or Reflection. Wavelength and the material and condition of the feature.
How is a spectral signature made?
The amount of energy that interacts with an object varies with wavelength and allows us to identify different substances or classes.
What two primary platforms are there for remote sensing?
Satellite remote sensing and aerial photography.
What does contrast stretching do?
Uses band statistics to stretch range of values across entire 0-255 display range
What does pan sharpening do?
Fuses a high resolution image with a low resolution multispectral image to create a pseudo high resolution color image
What is photointerpretation?
The visual process of identifying objects in imagery by using visual cues such as tone, texture, shape, size, shadows and location.
What is image classification?
The digital process of identifying objects by grouping pixels with similar spectral characteristics.
What are the two image classifications and how are they different?
Supervised and Unsupervised. Supervised is when an analyst identifies representative training sites for each class and the algorithm identifies the rest using this id. Unsupervised is when an analyst chooses the total number of classes desired.
What is a vegetation indices?
The reflectance in vegetation which helps identify type and health of plants. Generally a simple math formula using multiple bands of wavelengths. Uses R and NIR most because plants absorb R and reflect NIR.
What is GPS?
A location system used for estimating absolute positions. Satellites have a precise time it broadcasts its location and the receiver on earth updates its clock and computes the distance to the satellite.
What is DOP?
Dilution of precision that effects the alignment and geometry of satellites in sky.
