L1 Flashcards
What are 3 advantages of remote sensing data?
- Improvements over ground-based data collection
- New measurements available
- Synergy: lots of measurements able to be taken simultaneously
What purpose does ground-based measurements still serve?
They act to calibrate and validate remote sensing data
What are the two concepts of remote sensing?
Approach and sensor type
What are the 2 approaches to remote sensing?
Active and Passive
What are the 2 sensor types to remote sensing?
Imaging and non-imaging
Describe the imaging sensor type?
creates a picture by scanning across an array with its ‘swath’
Describe the non-imaging sensor type
makes individual point measurements
What are the 3 orbital parameters that affect remote sensing satellites?
- Altitude = defines the speed of orbit
- Eccentricity = defines the shape of the orbit
- Inclination = angle at which the sensor crosses the equator
What is the low earth orbit
Satellite that remotely senses in the altitude of 400-1000km above earth, around the poles (90 degrees to equator). It achieves a global coverage through repeated strips of orbit
What is the geostationary orbit?
Satellite that remotely senses at the altitude of 36,000km, the satellite stays in one position directly over the same position on earth. This means it orbits in time with the earth’s rotation.
What are the measurements from the geostationary orbit used for?
Weather and communication satellites.
How does altitude affect spatial resolution?
The higher the altitude the lower the spatial resolution
What are the 4 types of resolution for remote sensing?
Spatial, temporal, radiometric and spectral
What is spatial resolution?
The minimum separation of 2 discrete objects for them to be resolved individually
What is commonly used to reference the spatial resolution?
The grid size of the image raster
What is temporal resolution?
The ability to pinpoint events in time. Essentially how often time certain measurements are taken.
What is radiometric resolution?
The ability of a system to represent and distinguish differences of intensity.
How do you describe the mechanics of a computer’s system for radiometric resolution?
Binary
How does the radiometric resolution of sensor work?
So the computer’s binary system can be to the power of any number e.g. 2^4. The power then determines how many ‘bits’ which essentially means how many levels of intensity it has. So more bits means that there are more colours/shades that are available to represent things.
What is a signed integer?
Means that it can have negative values
What is an unsigned integer?
Means that all values will be positive.
How does whether something is a signed or unsigned integer affect the range of values in radiometric resolution?
Whether its signed or unsigned determines the range of values for the differing levels of intensity.
What value is important to remember when looking at the range of values for the radiometric resolution?
0
What is spectral resolution?
The ability to resolve features in the electromagnetic spectrum
What features in the electromagnetic spectrum do we most commonly look at?
Visible layers, NIR, SWIR, MICROWAVES
What are the categories that make up the electromagnetic spectrum?
Y rays, X rays, UV, Visible Light (blue, green, red), Infra-red, microwave, Radio waves (FM, AM), Long radio waves
