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4. High geometric accuracy 
5. Permanence of records 
6. Ability to synoptically analyze a given 
environment over a specific time span 
However, it is the ability of fcir imagery 
to enhance the subtle differences in reflec 
tance that are barely discernible to the hu 
man eye which gives it its greatest impor 
tance to wetland delineation and classifi 
cation. This is particularly so in delin 
eating the change from wetland, to transi 
tion zone to upland, where frequently, spec 
tral differences between vegetative species, 
water and soil moisture content, which are 
essential in establishing competitive ad 
vantage, are so small that they can and of 
ten are overlooked in field surveys; par 
ticularly field surveys of sites that have 
been impacted heavily by human actions. 
4 MANUAL IMAGERY ANALYSIS 
With an understanding of how fcir imagery 
functions, a return to the techniques of 
manual interpretation is in order. As pre 
viously stated, there are six interpreta 
tion parameters: color, height, texture, 
shape, site and association. The methodology 
of how these parameters are employed to es 
tablish wetland boundaries and vegetation 
types is accomplished in the following man 
ner. 
First, it is necessary to hypothesize, to 
make an educated assumption, of what exists 
within the project area. In the matter of 
Longridge, a "Given" had been provided by 
the client, determination that a Red Maple 
Swamp of approximately eighteen acres, ex 
isted. At issue were the size, boundaries 
and classification. 
The hypothesis to be tested, therefore, 
was one primarily concerned with delinea 
tion. Classification would essentially be 
used as confirmation. Manual imagery analy 
sis, as applied to this hypothesis, is basi 
cally a deductive process in which features 
and their identifying signatures lead the 
photogrammetrist to his delineation and 
classification. 
The next step in analyzing any terrain is 
to establish a point of beginning, a base 
line from which each element of the terrain 
is considered in a logical progression. In 
wetlands analysis, the photogrammetrist es 
tablishes a series of transect lines at 
right angles to the base line. In Longridge, 
the stream was chosen as the base line and 
transects were established at 100-foot in 
tervals. These transects ran east to west, 
progressing outward and topographically up 
ward from wetland to upland. Interpretation 
took place along these lines for classifi 
cation; whereas delineation took place at 
those points in which a change in classifi 
cation took place. 
The specific delineation and classifica 
tion of a wetland is the result of the con 
vergence of evidence. Critical examination 
of this evidence clearly establishes that 
only one interpretation is correct. It is 
very important to understand that imagery 
analysis is not performed in a vacuum; it 
requires three distinct and different aids. 
It is the utilization of these three aids 
which forms the third step in the analysis 
process. 
The first of these is Ground Truth, data 
obtained directly in the field either on 
site or in a terrain similar to the one be 
ing analyzed. This ground truth can be gen 
erated in-house or can be obtained from 
published documents of local agencies such 
as a soil and water conservation district. 
Image Analysis'Keys are the second aid, 
and these keys can be totally in-house gen 
erated, but in most cases have incorporated 
some signatures and descriptions established 
by others working in the same field of wet 
lands delineation and classification. The 
key utilized for Longridge was developed in 
1976, and expanded over a four-year period. 
It consists of signature characteristics 
and word descriptions and is organized on 
the basis of elimination. The following is 
an example from the key: 
Spring Film 2443 
Level I - Classification 
Descriptive Image Characterists 
Wetland Type 
Live Deciduous Tree Swamp 
Signature: standing water, trees 15 ft. 
or taller, trees have short 
trunks, many branches, rough 
texture, tight crowns 
Level II - Classification 
Signature : 
Color 
Height 
Texture Shape 
Wetland 
Type 
Green-Blue 
15ft+ 
Coarse 
Tight 
Red 
Crowns 
Maple 
Swamp 
Grey-Green 
Low 
Fine 
Dense 
Grassy 
Wet 
Meadow 
The final aid available to the photogram 
metrist is Imagery Interpretation and 
Transfer Equipment. Due to the scale of the 
imagery utilized, it is absolutely essen 
tial for interpretation that the photogram-r- 
metrist have available viewing equipment 
which permits him to view the site stereo- 
scopically and enlarged. Additionally, he 
must be able to measure horizontally and 
vertically. 
In the case of Longridge, a series of in 
struments were utilized as is the accepted 
practice by Stephen A. Estrin, Inc. First, 
for synoptically viewing the site and sur 
rounding terrain, a Dietzen Mirror Stereo 
scope, 6x power was used with a parallax 
bar. The parallax bar permitted vertical 
measurement of heights of trees to be made 
utilizing the floating dot principle. This 
permitted an overall evaluation and allowed 
a Class I classification of the wetland. 
For detailed classification and delineation, 
a Bausch & Lomb Zoom Transfer Scope was uti 
lized. The ZTS permitted the imagery to be 
enlarged fourteen times, and the transfer 
of delineated boundaries directly to a base 
map by scale matching. It also superimposed 
the imagery on the base map when the scale 
was matched, and thereby permitted the 
photogrammetrist to directly draw the wet 
land boundary as he was interpreting it. 
Finally, the ZTS permitted the photogram 
metrist to isolate areas requiring more 
detailed examination, and therefore more 
accurate classification. This was achieved 
by maximum enlargement of fourteen times 
imagery scale and 360 degree imagery ro 
tation . 
5 CONCLUSION 
Many photogrammetrists have demonstrated the 
applicability of remote sensing to wetland 
vegetation analysis in a variety of terrains. 
Seher and Tueller (T973) studied Nevada Wet 
lands utilizing color and fcir imagery. In