Title Page
        Page 1
    Summary
        Page 2
    Introduction
        Page 2
    Methods
        Page 2
    Results
        Page 3
        Page 4
    Literature cited
        Page 5

A COMPARISON OF
CATTAIL (Tvypha sp.) OCCURRENCE
ON A PHOTO-INTERPRETED MAP
VERSUS A SATELLITE DATA MAP
by
Jennifer E. Mattson,
John R. Richardson
and Wiley M. Kitchens



Department of Wildlife and Range Sciences
118 Newins-Ziegler Hall
University of Florida


through the


Florida Cooperative Fish and Wildlife Research Unit
117 Newins-Ziegler Hall
University of Florida


February 1991


Technical Report #40









A COMPARISON OF
CATTAIL (TvDha sp.) OCCURRENCE
ON A PHOTO-INTERPRETED MAP
VERSUS A SATELLITE DATA MAP


SUMMARY

A comparison between a 1985 photo-interpreted vegetation map
and a vegetation map made from classified 1987 satellite data of
the Loxahatchee National Wildlife Refuge showed that 81% of
samples taken in areas occupied by cattail (Typha sp.) on the
photo-interpreted map corresponded with cattail on the satellite
data map.


INTRODUCTION

Under contract to the National Wetlands Inventory, U.S. Fish
and Wildlife Service, Martel Inc. created a vegetation map of the
Loxahatchee National Wildlife Refuge by interpreting 1983-1985
1:58000 NHAP color infrared aerial photography. The National
Wetlands Inventory planned to digitize this map for inclusion in
a computer database for Loxahatchee National Wildlife Refuge, but
the complexity of the map made this unfeasible. Instead, the
Florida Cooperative Fish and Wildlife Research Unit performed a
computer classification of 1987 SPOT satellite data, (scene id
16232978704041559122X and 16232978704041559101P), to generate a
map of the wildlife refuge in digital form (Richardson et al.
1990).
Photo-interpretation has been used to test the accuracy of
classified satellite data (Dicks et. al. 1990). A visual
comparison of the photo-interpreted and satellite data maps
indicated that the extent of cattail (Tvpha sp.) on the satellite
data map appeared to be less than that on the photo-interpreted
map. Because the occurrence of cattail is central to important
ecological and management questions (Richardson et al. 1990), a
quantitative comparison of its occurrence on these two maps was
desired.

METHODS

The Fort Lauderdale 2NW Quadrangle of the U.S.G.S. 7.5
minute orthophotomap series contains roughly 50% of the cattail
in the Loxahatchee National Wildlife Refuge, and was selected as
the site for map comparison. Sample points were taken from this
selected region within all areas identified on the photo-
interpreted map as cattail. 366 samples were taken by randomly
placing a 1/4 inch grid over the map, and digitizing the location
of all grid points within the cattail areas that were more than
.5 mm from boundaries with other vegetation types. The grid
cells correspond to 500 feet on the ground.









A COMPARISON OF
CATTAIL (TvDha sp.) OCCURRENCE
ON A PHOTO-INTERPRETED MAP
VERSUS A SATELLITE DATA MAP


SUMMARY

A comparison between a 1985 photo-interpreted vegetation map
and a vegetation map made from classified 1987 satellite data of
the Loxahatchee National Wildlife Refuge showed that 81% of
samples taken in areas occupied by cattail (Typha sp.) on the
photo-interpreted map corresponded with cattail on the satellite
data map.


INTRODUCTION

Under contract to the National Wetlands Inventory, U.S. Fish
and Wildlife Service, Martel Inc. created a vegetation map of the
Loxahatchee National Wildlife Refuge by interpreting 1983-1985
1:58000 NHAP color infrared aerial photography. The National
Wetlands Inventory planned to digitize this map for inclusion in
a computer database for Loxahatchee National Wildlife Refuge, but
the complexity of the map made this unfeasible. Instead, the
Florida Cooperative Fish and Wildlife Research Unit performed a
computer classification of 1987 SPOT satellite data, (scene id
16232978704041559122X and 16232978704041559101P), to generate a
map of the wildlife refuge in digital form (Richardson et al.
1990).
Photo-interpretation has been used to test the accuracy of
classified satellite data (Dicks et. al. 1990). A visual
comparison of the photo-interpreted and satellite data maps
indicated that the extent of cattail (Tvpha sp.) on the satellite
data map appeared to be less than that on the photo-interpreted
map. Because the occurrence of cattail is central to important
ecological and management questions (Richardson et al. 1990), a
quantitative comparison of its occurrence on these two maps was
desired.

METHODS

The Fort Lauderdale 2NW Quadrangle of the U.S.G.S. 7.5
minute orthophotomap series contains roughly 50% of the cattail
in the Loxahatchee National Wildlife Refuge, and was selected as
the site for map comparison. Sample points were taken from this
selected region within all areas identified on the photo-
interpreted map as cattail. 366 samples were taken by randomly
placing a 1/4 inch grid over the map, and digitizing the location
of all grid points within the cattail areas that were more than
.5 mm from boundaries with other vegetation types. The grid
cells correspond to 500 feet on the ground.









A COMPARISON OF
CATTAIL (TvDha sp.) OCCURRENCE
ON A PHOTO-INTERPRETED MAP
VERSUS A SATELLITE DATA MAP


SUMMARY

A comparison between a 1985 photo-interpreted vegetation map
and a vegetation map made from classified 1987 satellite data of
the Loxahatchee National Wildlife Refuge showed that 81% of
samples taken in areas occupied by cattail (Typha sp.) on the
photo-interpreted map corresponded with cattail on the satellite
data map.


INTRODUCTION

Under contract to the National Wetlands Inventory, U.S. Fish
and Wildlife Service, Martel Inc. created a vegetation map of the
Loxahatchee National Wildlife Refuge by interpreting 1983-1985
1:58000 NHAP color infrared aerial photography. The National
Wetlands Inventory planned to digitize this map for inclusion in
a computer database for Loxahatchee National Wildlife Refuge, but
the complexity of the map made this unfeasible. Instead, the
Florida Cooperative Fish and Wildlife Research Unit performed a
computer classification of 1987 SPOT satellite data, (scene id
16232978704041559122X and 16232978704041559101P), to generate a
map of the wildlife refuge in digital form (Richardson et al.
1990).
Photo-interpretation has been used to test the accuracy of
classified satellite data (Dicks et. al. 1990). A visual
comparison of the photo-interpreted and satellite data maps
indicated that the extent of cattail (Tvpha sp.) on the satellite
data map appeared to be less than that on the photo-interpreted
map. Because the occurrence of cattail is central to important
ecological and management questions (Richardson et al. 1990), a
quantitative comparison of its occurrence on these two maps was
desired.

METHODS

The Fort Lauderdale 2NW Quadrangle of the U.S.G.S. 7.5
minute orthophotomap series contains roughly 50% of the cattail
in the Loxahatchee National Wildlife Refuge, and was selected as
the site for map comparison. Sample points were taken from this
selected region within all areas identified on the photo-
interpreted map as cattail. 366 samples were taken by randomly
placing a 1/4 inch grid over the map, and digitizing the location
of all grid points within the cattail areas that were more than
.5 mm from boundaries with other vegetation types. The grid
cells correspond to 500 feet on the ground.









Using ERDAS image processing software, the sample points
were compared with the classified satellite data map. The ERDAS
program POLYCAT finds the pixels (picture elements) in the
satellite map which correspond to the locations of each sample
point. The program then looks at a square block of 9 pixels
centered around each sample point pixel, and identifies the
vegetation class which occupies the majority of the block. If
there is no majority class within the block, the program
identifies the vegetation class of the sample point pixel itself.
The vegetation class for each sample point is then written to a
file.

RESULTS

The digitized sample points were tallied by their satellite
map vegetation class to produce Table 1. 81% of the sample
points fell into one of the three cattail classes on the
satellite map. The remaining sample points were classified as
other vegetation types.










Table 1. Cross reference of sample points photo-interpreted
as cattail (Tvyha sp.) on the National Wetlands Inventory map of
Loxahatchee National Wildlife Refuge and their vegetation classes
on the Florida Cooperative Fish and Wildlife Research Unit's
classified satellite data map.


Class Vegetation Class Number of
Number* on Satellite Map Samples


10 Cattail (close to canal) 157
18 Cattail 107
2 Cattail (invading sawgrass) 31
16 Sawgrass 13
14 Brush/tree island 12
3 Sawgrass 9
4 Brush/sawgrass 9
17 Willow 9
1 Sawgrass 7
15 Sawgrass/brush 6
6 Wet prairie 5
9 Sparse wet prairie 1
5 Tree island 0
7 Tree island 0
8 Brush 0
11 Open water 0
12 Slough 0
13 Willow 0

Column total 366

Cattail correspondence: 81%

* See Richardson et al. 1990 for complete description of classes.









LITERATURE CITED

Dicks, Steven E., and Thomas H. C. Lo. 1990. Evaluation of
thematic map accuracy in a land-use and land-cover mapping
program. Photogrammetric Engineering and Remote Sensing
56:1247-1252.

Richardson, John R., Wade L. Bryant, Wiley M. Kitchens, Jennifer
E. Mattson, and Kevin R. Pope. 1990. An evaluation of
refuge habitats and relationships to water quality, quantity
and hydroperiod. A synthesis report. November 1990. 167
pp. Florida Cooperative Fish and Wildlife Research Unit,
University of Florida.