Geo 213 Final II Flashcards
Principal point
geometric center point on photograph
Field of view
angular measurement of how much landscape you can see
High oblique
can see horizon
Low oblique
~45°
Vertical
trying to create “map-like” product
High ISO
FASTER shutter speeds MORE noise (less effective resolution)
Low ISO
SLOWER shutter speeds LESS noise (more resolution)
Additive
Red
Green
Blue
Subtractive
Yellow
Cyan
Magenta
Digital camera
1) solar cell converts photons into electrons
2) matrix of solar cells each capable of producing a voltage
3) voltage converted into digital number 0-255
=intensity of blue, green, red
Radiometric resolution
how many bits are available to store brightness
-higher resolution = more shades
=(more memory)
Image elements triangle
Primary - tone/color
Secondary - texture, shape, size
Tertiary - pattern, height, shadow
Higher - site, association
Small scale
cover MORE area
is LESS detailed
Large scale
covers LESS area
is MORE detailed
Three types of scale representations
graphic scale
verbal scale
ratio / representative fraction
Geospatial intelligence
Imagery
Imagery intelligence
Geospatial information
Preprocessing
converting raw imagery into form we can start to make sense of
- geometric correction
- radiometric correction
Basic image display
over 210 possible B,G,R color combinations (7 bands)
- THERMAL
- Red = B
- IR = G
- Thermal = R
Supervised classification
1) user picks set of land cover class scheme (urban, agriculture…)
2) user identifies examples for each type on image
3) based on collected pixels, user looks at the signatures
4) computer goes through every pixel and matches them with classification
PROBLEMS:
-ambiguity
-different spectral signatures, same class
-mixed pixel problem
Unsupervised classification
1) user selects study area + preprocesses
2) user has vague idea of number of types in image
3) computer uses statistical analysis to clump like pixels (creates classifications)
4) user assigns names to these clumps
PROBLEMS:
-can’t differentiate (red on computer = agriculture AND forest)
=may not be useful for your study
Color star
FROM TOP, CLOCKWISE Red Yellow Green Cyan Blue Magenta
Spatial resolution a function of…
Matrix size
Distance from target
Quality of optics
Quality of electronics
Multi
multi-station - use of overlapping photos taken along a given flight line
multi-band - individual bands within a given region of the EM spectrum
multi-spectral - images from various regions of the EM spectrum (thermal, visible, radar…)
multi-temporal - images of same target taken at different times/seasons
multi-stage - image taken from different altitudes
