Lecture 8 - App. RS

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App. Remote SensingApp. Remote Sensing 11

Lecture 8

Land Application

Land Use/Land Cover:

Land use is the use of land by human with

emphasis n the functional role of land in

economic activity; Land cover is the designation of land for

vegetative and nonvegetative uses;

RS is used accurately map land use and land

cover information because visual interpretationcan be made


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Land Use Classification:

The most common application of remotely-

sensed images in land evaluation is that ofland

cover classification, also called a land use map;

Spectral characteristic in a multi-band image can

be used to separate different land uses;

- Satellite-based land cover classification is often

the only practical ways to do this over large

areas;

The spectralcharacteristics of the different landcovers must be associated with each land cover

class, then the entire image can be classified.


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Whyis land cover classification important in

land evaluation? Many uses depend on the presence or absence

of certain land cover;

The present land cover can itself be diagnostic

for suitability, e.g. natural vegetation indicativeof a certain hydrologic status;

Predictive models for land evaluation may

require land cover information; e.g 'C' factor in

the USLE. Also, predicting runoff from storms

using the SCS Curve Number method depends

heavily on current land cover;


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The USGS system was prepared specifically

for use with remotely sensed imagery; Appropriate for information interpreted from

aerial images;

Hierarchical structure can be used with

images of different scales and resolution; Level I: For use with broad-scale, coarse-

resolution imagery (Landsat imagery or

high-altitude aerial photograhy

-general kind of land use (urban,agricultural, rangeland, forest, water,

wetland, barren land, tundra, and perpetual

snow & ice),


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Level II and III: More detailed classes that can

be interpreted from large-scale, fine-resolutionimages;

-major land use (e.g., residential, cropland)

Level II;

-specific kind of land use (e.g., single-family

detached dwellings, winter small grains) Level

III:

Each level is appropriate to a particular spatial,

temporal, and spectral resolution of the

supporting imagery.


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Land-Cover Mapping by Image

Classification:1. Image Selection: Selection of images with

respect to season and date;

- i.e. what season will give the optimum

contrast between the classes being mapped

two or more seasons might be required to

separate all classes of significant;

2. Preprocessing: Accurate registration and

correction for atmospheric and systematic

errors;- Subsetting of the region to be examined


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3. Selection of classification algorithm: Should

be made on the basis of local experience;- Local experience and expertise are a more

reliable guide for selection of classification

procedures;

4. Selection of training data: Training data must

be carefully selected fro each class to ensure

good representation of spectral subclasses;

5. Assignment of spectral classes to

informational classes: Aggregation of

spectral classes and their assignment toinformational classes;

6. Displayand symbolization:


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RS in Plant Science:

All solar radiant flux incident upon any object iseither reflected, transmitted, or absorbed,

vegetation is however unique in its three-

segment partitioning of solar irradiance;

In the visible part of the spectrum (0.4-0.7 m),reflectance is low, transmittance is nearly zero,

and absorptance is high

In this part of the spectrum the fundamental

control of energy-matter interactions with

vegetation is plant pigmentation;


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In the longer wavelengths of the near-infrared

portion of the spectrum (0.7-1.4 m), both

reflectance and transmittance are highwhereas absorptance is very low;

- the physical control is internal leaf

structures;

The middle-infrared sector (1.4-2.5 m) of thespectrum for vegetation is characterized by

transition;

As wavelength increases, both reflectance and

transmittance generally decrease from mediumto low

- Absorptance, on the other hand, generally

increases from low to high;


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Spectral Behavior of Living Leaf:

The dominant plant pigments are the chlorophylls;

Chlorophyll absorb as much as 70-90% of incidentlight mainly blue and red;

Chlorophyll-bearing vegetation appears green due to a

minor reflectance peak in 0.5-0.6 m wavelengths.

In the NIR portion of the spectrum, reflectance iscontrolled by the structure of the spongy mesophylltissue not the pigmentation;

In longer IR wavelengths (beyond 1.3 m) leaf watercontent control spectral properties;

The term equivalent water thickness (EWT) - thicknessof a film of water can account for the absorptionspectrum of a leaf at 1.4-2.5 m;


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During stress or senescence, however,

chlorophyll production usually declines and blueabsorption (i.e. yellow reflectance) become

obvious;

As plant senescence progresses, the changes in

relative abundance of the various pigments areaccompanied by shifts in spectral absorptance

and reflectance;


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Lecture 8 - App. RS