Image Acquisition Flashcards
Aerial Photography operates in…
-Visible and NIR
Metric Cameras - vertical optical axis
V high geometric fidelity
Photogrammetry is…
Determining geometric properties of objects from photos
Interpretive Photogrammetry
Identification and systematic analysis of ground based object info
- Qualitative
- Distance between 2 points on plane parallel to image plane = distance in imagery plane
Stereo Photogrammetry
3D coordinate estimated from 2+ images from different positions
-Calculation requires at least 3 known object points
Electro-optical (V/NIR)
Spectral range similar to aerial photography
Digital detection - 2D Photodiode array (CCD’s)
Deployed from - aircraft + satellites
Eg Landsat ASTER MODIS IKONOS SPOT
Electro-optical (V/NIR)
- SCANNING
1. ) Step-stare
2. ) Pushbroom imaging
3. ) Whiskbroom
- ) EMR focused on 2D CCD array + imaged instantaneously
- ) EMR focused onto 1D array + viewing in narrow strip
- ) EMR focused onto single element (Most common)
Most VIR imagers are…
multispectral, some hyperspectral
Landsat
1-4
4-5
7 (Enhanced Thermatic Mapper)
multispectral (G,R,NIR,IR)
Thermatic mapper
Panchromatic
SPOT improves on…
Landsat 7
with off nadir jobs
HRV sensors (Higher Spatial Res)
SPOT vs Landsat
SPOT = much smaller image area
ASTER
Advanced Spaceborne Thermal Emission and Reflection Radiometer
Japan/US effort - multispectral (14) + Back looking for stereo
CERES
Clouds and the Earth’s Radiant Energy System
MISR
Multi-Angle Imaging Spectroradiometer
MODIS
Moderate-resolution Imaging Spectroradiometer
36 band multispectral
MOPITT
Measurement of Pollution in the Troposphere
IKONOS
V fine resolution
0.83m for Panchromatic
4m for multispectral
GeoEye-1
2x resolution of IKONOS
Thermal IR systems use….
wavelengths 8-14 micrometers
TIR systems are used for
surface temps
coarser spatial resolution than Landsat
AATSR
Advanced along Track Scanning Radiometer
Maps sea surface temp
Doesn’t penetrate clouds
Passive microwave detects…
black-body radiation in MW part of spectrum
Wavelength = 3-6 m
Penetrates clouds
V coarse resolution
Laser Ranging uses emission of…
pulse of light and time taken for reflection to return
Vertical resolution 0.1m possible
Satellite laser altimetry uses….
IR and visible
GLAS = Geosciences Laser Altimeter System
Radar Altimetry is similar to…
Laser altimetry
Can observe through clouds
Waveform= info about roughness
Slope error can be a factor
Radio-echo sounding used for….
englacial and subglacial properties
Imaging radar/ scatterometry is transmitting of…
MW which are scattered and reflected
Scatterometry involves the…
emission of a pulse which is scattered back to a sensor
SAR=
Synthetic Aperture Radar
SAR uses…
forward motion to synthesise very long antenna = greater resolution
Forshortening results in…
strange geometry due to measure of travel time not angle
