The ATLSS Habitat Type Density Analysis Maps
These pages present information
for both the ATLSS Habitat Type Density Analysis, and a
similar collection of habitat images for the Florida Department of
Transportation (DOT) data.
Section 1 : The ATLSS Habitat Type Density Analysis Maps.
The ATLSS Habitat Type Density
Analysis Maps (HTDAM) are derived from the maps created
by the Florida GAP analysis project (FGAP).
The FGAP maps provide information about the distribution
and abundance of habitat types within Florida.
We are currently showing here the results from both the
2.1 and 3.0 versions of the FGAP map.
The two versions differ in a
number of respects, most notably in the geographical
extent of Florida included in the map.
Version 2.1 covers the entire width of Florida from
just below Lake Okeechobee south to the end of the
The 3.0 version expands the area covered further north.
This map's most northerly extent covers the area of
Lake Tohopekeligo, near Orlando, and extends south through
Figures 1 and 2 show the spatial extent of the two
version of the FGAP map.
The two versions also differ
in the number of habitat types included.
These habitat types represent a broad classification of
vegetation as well as urban and agricultural use.
The vegetation classification system used is The Nature
Conservancy's (TNC) Habitat classification system.
The 2.1 version of the FGAP map includes a total of 80
habitat types, 42 of which represent vegetation.
The 3.0 Version of the habitat map contains nearly 128
habitat types of which 82 represent vegetation.
In each case the remaining habitat types describe urban
and agricultural classifications.
Both versions of the FGAP
are represented by a raster map.
In each case, a single pixel in the map represents a
square on the ground 28.5 meters on a side.
For the 2.1 version of the map, this results in 9732
rows and 8220 columns, or a total of more than
For the 3.0 version of the map, the area is covered by
16245 rows and 10067 columns for a total more than
For each of these cells, the FGAP map contains a single
index representing the dominant habitat type present
within this area.
There is much more to know about the FGAP map and the
project in general.
For more information please visit
their web site
The ATLSS Habitat Type Density Analysis
takes the FGAP map and views it as a series
of separate maps, one for each habitat type.
This approach was taken to simplify the task of
visualizing the distribution and abundance of each of the
To attain this goal of simplifying visualization, a number
of processes have been applied to the original map.
The first thing you will notice
is that the HTDAM covers a smaller spatial extent than the original
This is a result of the focus and purpose of the ATLSS project.
Without getting into too much detail, ATLSS is primarily
focused on the area between the southern end of Lake Okeechobee
and the southern end of the Everglades National Park (ENP).
For more information about why ATLSS focuses on this region,
please see the ATLSS web site at
The second difference between
the HTDAM and the FGAP images is the spatial resolution.
The HTDAM is also a raster map, for which each pixel in
the map represents a square on the ground 500 meters on
This resolution matches many of the ATLSS models.
At this resolution it is also possible to see each pixel
and still keep the overall map size manageable.
In order to see every pixel of the 28.5x28.5 meter version
of the FGAP, the map would need to be so large that it would be
impossible to view the entire map at one time.
The final and crucial difference
between an FGAP map and the ATLSS HTDAM is that a FGAP map shows
all habitat types at one time while the HTDAM shows a
single vegetation type for each map.
The approach taken in the HTDAM has a number of advantages.
The FGAP map contains so much information that it is frequently
difficult to see clearly the full extent of a habitat type, and
difficult to understand how its density varies across the
This is especially true of habitat types which exist at low
densities within their distribution.
These types occupy a small number of pixels relative to surrounding
types and many be difficult to see.
Even for types which are very common, near the edges of their
distribution they may become very sparse, making them difficult
to locate or distinguish from surrounding types which locally
may be more abundant.
By viewing each habitat type individually, it becomes clear how
the density of the type varies within its range, and the extent
of its distribution is easier to discern.
This approach is not appropriate for all purposes, since information
about how a type co-varies with other habitat types, both in
density and distribution, is lost.
However, for many purposes this mode of visualization is powerful
For each habitat type present within
an FGAP map, there is one HTDAM map.
The cells of an HTDAM map are colored based upon the fraction
of the cell covered by a habitat type.
The relationship between cell color and frequency is given by the
color bar which appears on the right hand side of each HTDAM map.
The colors are graded continuously from blue through cyan, green,
yellow, red and finally magenta.
Cells colored blue contain very little of a given habitat
type, while cells colored magenta are completely covered by a habitat
When a habitat type is not present within a cell, the cell is
Figure 3 show an example of the color bar as it appears in these
The color bar can also be seen at the top of this page, where
its location relative to this text is also its location relative
all HTDAM maps.
Drawn over the HTDAM maps in white
are the outlines of some important management areas.
These are provided as a means of reference.
At the top of each HTDAM map is a short description of the
habitat type being displayed.
The associated number gives the index assigned to represent the habitat type
in an FGAP map.
The text gives the TNC description provided for that type.
Note that the 3.0 and 2.1 versions of the FGAP map use different
sets of indices, so type 23 in the 2.1 version of the map may
not be type 23 in the 3.0 version.
The black areas which appear in the HTDAM maps represent either
ocean or areas not within an FGAP map.
Section 2 : Habitat images for the Florida Department of
Transportation (DOT) maps.
In addition to the HTDAM, these pages include
the images created for the Florida Department of Transportation map.
The DOT map covers approximately the same area as the 2.1 version of
the FGAP, but uses only 19 habitat types.
The images which we have created from the DOT map are much simpler
than the HTDAM maps.
As in the HTDAMs, one map has been created for each habitat type
appearing in the DOT map.
However, the pixels for this map show only presence or absence.
This means that there
is no information about the fraction of a cell covered by a habitat
The color of the pixels in these maps DO NOT
correspond to the fraction of a cell covered.
The color or each cell is the color used to represent the habitat type in
the DOT map.
The color black is used both to indicate absences of a habitat type
from a particular area, and as the background color.
A white outline of the area covered by the DOT map appears on each image
to provide a frame of reference.
The boundaries which appear in the HTDAM maps are not present in
the maps created for the DOT data.
The ATLSS project no longer makes use of the DOT map, There presence
here are included only for completeness.
We welcome any comments you wish
to make about any aspect of these pages.
If you encounter errors in our presentation, broken links,
or simply wish to tell us what you think, please
e-mail us at firstname.lastname@example.org.