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35 Cards in this Set
- Front
- Back
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What is remote sensing |
there is interpretation of information about the earth’s surface withoutactually being in contact with it. |
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Spectral reflectance of remote sensing methods |
will vary |
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what does the term "fit for purpose" mean |
consider the resolution required for your study |
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What is considered accurate in remote sensing |
getting the true point of an object from GPS, different processes have different accuracy |
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What is free data |
landsat - 1970s onwards |
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data is now commonly collected and stored in what form |
digital |
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data form is important why? |
for provenance + level of contamination of data |
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Draw back of remote sensing data collection |
Often constrained by the real world – budget cuts etc. also dependent on what’s viewed asnecessary. |
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Snapshot measurement means |
only ever a snapshot, not an average, on valid for day of capture. |
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Types of analysis from remote data |
- Interpretive - Mapping and digitising in both 2d and 3d - Image processing - Classification - Change detection |
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Advantages of RS |
- Non-intrusive - Uncontaminated data source - Some low – skill technique - Allows retrospective monitoring - Multitude of applications - Cost effective - Wide range data |
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Disadvantage of RS |
• Not always in control of data capture • Redundancy • Cost • Accuracy/precision |
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There has been how many differing landsat satellites |
8 with 3 useful sensors |
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What is ETM+ |
sensor on landsat 7 was the best quality of them all. |
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Sensor types |
traditional film cameras digital sensors passive and non-passive sensors many platforms |
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passive sensors will use what energy |
collect energy from sun ambient light as reflected from a surface, no active pulse of energy from sensor |
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examples of passive sensors |
film based camera and digital camera - aerial and handheld |
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what is an active sensor |
a sensor which carries on board its own electromagnetic radiation source |
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example of active sensor |
radar, lidar, flash camera, sonar |
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what is lidar |
microwave sensing |
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what wavelengths does lidar cover |
1cm to 1m |
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why microwaves? |
they can penetrate through cloud cover, haze and dust. They are not effected by atmospheric scattering |
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Image availability is a concern, why? |
availability is difficult, due to user being at mercy of what is available from companies |
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What does temporal resolution mean |
refers to how often the same geographic area is revisited by a sensor |
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Temporal resolution enables the view of... |
change through time e.g. glacial movement |
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What is spectral resolution? |
defined as the number and width(wavelength) of bands of electromagnetic energy detectable by agiven sensor |
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What range of wavelength is spectral resolution limited to |
the visible and low end of the near infra-red section of the electromagnetic spectrum |
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Aerial photographs: image type |
softcopy (digital) hardcopy (paper or film) |
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Aerial photographs: Image availability |
vertical or oblique |
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Principles of stereovision |
• Stereovision improves our ability to perceivedepth • Some people unable to perceive in stereo • Humans (and other predators) have 2 eyesfacing forwards • Each eye gets an image of the scene,slightly separated • Process understood since the Renaissance |
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TIFF Files useful because |
they are lossless |
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JPEG means |
Joint Photographic Experts Group |
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What does the compression method of JPEG file result in |
very lossy |
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ECW is a lossy format used by who? |
Channel Coast Observatory |
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What file type does erdas use to store raster data |
.img |
