EAS 221

Geographic information system: integrates hardware, software, and data for capturing, managing, and displaying all forms of geographically referenced information

Grid. Cells that each have a state/contain information

Point, line, polygon. Gives us just what we want (like lines on a map representing roads)

Non-spatial data. Attributable and assigned to spatial locations (ex. names, populations attached to any point).

Earth's surface and near-surface

Any space (including geographic) ex. medical imaging

Canada Land Inventory (1960)

Launched in 1972, first orbital satellite that was designed for environmental studies

• Gathering of data about the earth and environment by satellite sensors
• Using information that's contained in the electromagnetic radiation reflected from an object

Volume of area, object of interest

Orbital characteristics; how often a certain satellite revisits a certain location

the fineness of the chunks of waves a sensor can identify

• pixel size, ex. digital camera resolution
• the more pixel resolution, the more detailed

sensor itself provides the energy initially needed as well as receiving

relies on the sun as the source for electromagnetic radiation

data about the data (so meta)

resolution quantifies how close lines can be to each other and still be visibly resolved

• frame
• scanner
• pushbroom
• whiskbroom

instantaneous field of view, area of the ground viewed at one spot

examples of the spectra from the pure individual elements within a pixel

• determination of distances, areas, and directions
• importance of precise height and attitude(?) information

distance from one peak to the next

number of peaks passing a fixed point over a period of time

height of each peak (related to energy and brightness)

frequency (v) x wavelength (lambda)

400nm-700nm

• "perfect absorber" (also perfect emitter)
• all materials emit radiation at a given temp and frequency exactly as well as it absorbs the same radiation

the shape of the blackbody radiation curve is the same at all temperatures

3um (3000nm)

when a ray of light is redirected as it strikes a surface

surface is smooth relative to the wavelength

when the surface is rough relative to the wavelength

particles are smaller than wavelength of light, more scattering, more absorbance

particles are about same size as wavelength of light, similar amount of each wavelengths comes through (whiteness of clouds)

particles are bigger than the wavelengths of light, lets us see dark things like smog, smoke, etc.

range of wavelengths in the EM spectrum in which radiant energy is absorbed by a substance

regions of the spectrum in which the atmosphere is absorbing all the EM energy are not visible from space

regions of the EM spectrum where the atmosphere is absorbing little or not at all. EM energy can be used to observe the surface of the earth.

Information received by sensor (in watts per square meter per steradian)

ratio of reflected versus incoming radiant flux (ex. brighter a surface the higher its reflectance)

Making two image layers correspond (same scale, making sure they line up)

• Process of assigning map coordinates to image data 
• Giving it spatial coordinates

3D terrain correction

• 1. Rectification
• 2. Resampling

Ground control points: x, y coordinates of known locations

Assigns a pixel value based on nearest pixel in original matrix to a given pixel in the output matrix

assigns a value based on a weighted linear average of the 4 nearest pixels in the original matrix

Assigns a value to a given cell in the output matrix based on a 4x4 moving average calculated using a cubic polynomial

digital number

a measure of the ability of a spectrometer to resolve features in the electromagnetic spectrum

the regions (bands) of the EMR that are detected by the sensor

Characterized by relatively small number of spectral bands (<30)

Characterized by hundreds of narrow spectral bands (>200)

• The sensitivity of a sensor to differences in signal strength/radiance
• the number of gray tones in a range

• Seem stationary above earth because they revolve with the same speed as the earth over the equator
• ex. weather satellites 
• can get as high a temporal resolution as you want

• Move North-South and pass close to poles
• only record data in the ascending pass (moving northward)

• Polar orbit that covers each area of the world at a constant local time of day called sun time
• always in light
• can collect data 24/7

• Identifying spectrally similar areas on an image by identifying "training" sites of known targets, then using those spectral signatures to classify other areas of unknown targets
• (need previous knowledge of area for this)

Categorization of digital image data based solely on the image statistics w/out availability of training sites, no prior knowledge of the area

Grouping image pixels from different spectral bands into categories or classes

Normalized Difference Vegetation Index

incoming radiation - (reflection + transmission)

Chlorophyll a and b, carotenoids,

ex. takes vegetation index data from 3yrs of forest fire data

Following actual classification

Spectral mapping of taxonomic diversity

• Clouds
• Humidity
• Precipitation
• Aerosols

Colder

Geostationary Operational Environmental Satellite

Advanced Very High Resolution Radiometer

• Light Detection and Ranging
• wavelengths of 400-1500nm

• Cloud profiling radar CPR
• Uses microwaves