Full text: Remote sensing for resources development and environmental management (Volume 2)

the color cartographic photography was ana 
lyzed to determine the hydrogeology of the 
site and in conjunction with a Balplex 760 
High Precision Stereoplotter, verification 
of the topography shown on the survey of the 
site was made. 
Finally, historical black and white serial 
photography on file in the photogrammetric 
library of Stephen A. Estrin, Inc., dated 
1968 and 1970, with a scale of 1"=2000', 
provided the means of synoptically analyz 
ing the site over a critical six year per 
iod; critical due to the interdiction of 
this once continuous and extensive wetland 
by the construction of 1-84. Essential to 
wetland delineation and classification is 
the impact of man-made structures. 
2 REMOTE SENSING IMAGERY ANALYSIS 
2.1 General 
Most remote sensing imagery analysis re 
quires the photogrammetrist to have at his 
command data other than that directly ob 
tained from the imagery being examined. 
This is referred to as Ground Truth. 
The development of a County Land Develop 
ment Plan and the Southeast Sewer Study gen 
erated a considerable amount of geophysical 
data relatino to this site. The photogram 
metrist, therefore, had available Ground 
Truth on soils, geology, topography, ground- 
water systems, drainage, vegetation, wet 
lands and existing land use. The sources of 
this data were both in-house field surveys 
and county agencies, most notably the 
County Soil and Water Conservation District. 
Additionally, the State of New York, De 
partment of Geology has published Bedrock 
Geology Maps, and the Kensico Water Shed 
Maps prepared photogrammetrically for the 
New York City Department of Water were also 
utilized. 
2.2 Interpretation Techniques 
Although the field of Remote Sensing has 
developed rapidly since the early 1970's, 
most applications of Remote Sensing for In 
land Wetlands have, and still use, aerial 
photography and imagery in conjunction with 
manual interpretation rather than digital 
imagery analysis techniques of multi-spec 
tral sensed data. The reason for this is 
due to the heterogeneity of wetlands, the 
varying vegetation species and their loca 
tions within an environment of varying 
moisture content. 
Under such conditions, "Spectral Signa 
tures" are often overlapping, and there 
fore, confusing. The Spectral Signature of 
a feature is a set of values for the re 
flectance or the radiance of that feature, 
where each value corresponds to the reflec 
tance or radiance averaged over a different, 
well-defined wavelength interval. It is with 
in these different wavelengths of the elec 
tromagnetic spectrum that the overlap occurs. 
An "Imagery Signature", on the other hand, 
refers to a distinguishing characteristic 
only associated with a single feature or 
group of similar features defined by six 
parameters. These parameters include: 
1. Color - as expressed as a hue and tone, 
i.e., gray/green, red, magenta-violet-red 
2. Height - as expressed as a vertical 
distance from the ground, in feet 
3. Texture - as expressed by a word pic 
ture, i.e., coarse, coarse (mottled), fine, 
smooth 
4. Shape - as expressed as a geometric 
arrangement, i.e., rounded open crowns, 
arching limbs and long pendulous branch- 
lets 
5. Site - as expressed as a landuse type 
and terrain form, i.e., farmland, glacial 
till 
6. Association - as expressed as the in 
terrelation of natural features to one a- 
nother, swamp-standing water-tree species - 
ferns - club mosses at the outer boundaries 
These six parameters of fcir imagery in 
terpretation are of varying importance in 
terms of wetlands delineation and classi 
fication. Color, however, is undoubtedly 
the most important, followed by Height. The 
remaining four are supportive of these two. 
2.3 False Color Infrared Film 
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Kodak Aerochrome Infrared Type 2443 is the 
accepted standard fcir film used for wet 
lands delineation and classification by 
photogrammetrists. 
When viewing this imagery, there is a 
"field-of'view" which defines the common 
picture element. This is known as a Pixel. 
It is the grouping of these individual Pix 
els that determines what is seen on the im 
agery and permits interpretation by the pho 
togrammetrist. In the fcir used for wetlands 
delineation and classification, the Pixels 
are representative of reflected energy. 
Therefore, before consideration can be given 
to the specifics of wetland delineation and 
classification, it is necessary to under 
stand how fcir imagery functions. 
2.4 Light and Electromagnetic Spectrum 
Light, as the human eye perceives it, can 
be referenced to the electromagnetic spec 
trum of which the micrometre (Urn) is the 
basic unit of measure. It is divided into 
various wavelengths, representative of dif 
ferent types of reflected or emitted energy. 
In terms of the human eye and most photo 
graphic film, sensitivity is very narrow, 
between 0.4 and 0.7 Urn. Fcir imagery extends 
that sensitivity to 0.9 Urn. In both the hu 
man eye and fcir, the energy sensed is re 
flected. 
In terms of target interactions, reflec 
tion is defined as the amount of energy at 
various wavelengths that is returned to the 
sensor (camera) from a given object. This 
energy return can be quantified as either a 
unique spectral or imagery signature which 
is similar to a fingerprint. In fcir imag 
ery, this signature is defined by six para 
meters of which Color is the most important. 
Therefore, wavelength selectivity, the inter 
action of electromagnetic energy with ob 
jects (targets) within a given environment, 
is at the heart of fcir discrimination be 
tween these objects. The 2443 film has three 
emulsion layers; each sensitive to a differ 
ent portion of the electromagnetic spectrum, 
the green and ultraviolet portions - yellow 
layer; magenta portion - green layer; and 
infrared portion - red layer. 
3 FCIR IMAGERY - THE ADVANTAGES OF ITS USE 
1. Vantage Point - unique vertical perspec 
tive of terrain 
2. Resolution is greater than that of the 
human eye 
3. Spectral sensitivity over a range of 
the electromagnetic spectrum about twice as 
broad as the human eye; 0.4 Urn to 0.9 Urn 
4 MANUAL 
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