plant canopy can not be explained only by the characteristics of
this canopy. This way is important to know every the
characteristics of the landscape.
2. METHODS
2. Techniques and Softwares
The methodology implemented for this study addressed the
acquisition of Hyperion satellite imagery, pre-processing to the
scenes, samples selection for appointment of vegetation classes
and analysis of results from the spectral response graphs for
each class.
The acquisition was made by access to e-mail address:
http://glovis.usgs.gov. The image used was acquired by the
sensor on July 13, 2010.
During the pre-processing was used the software ENVI and the
tool hyperion tools.sav that allowed the inclusion of scenes and
correction of the noise characteristics, in the form LIR. Later
was selected the tool for converting raw data into a new file
format has the ENVI software. This procedure was necessary
because the step of atmospheric correction of images requires
scenes with the extension feature of the software.
Para a realizaçäo da correçäo atmosférica foi utilizado o modulo
FLAASH (Fast Atmospheric sigt Analyst Line of the Spectral
Hypercube) presente no software ENVI. The parameters
adopted for the implementation of atmospheric correction were:
- sensor altitude: 705 km (above sea level);
- mean elevation of the image area 0.6 km (kilometers above the
sea);
- pixel size 30m;
- UTC time - 12h38m$4s;
- atmospheric model "Mid-Latitude Summer";
- aerosol model - rural scattering algorithm MODTRAN -
ISAACS.
The final step corresponded to the geometric correction of the
scene from Digital Elevation Models on the scale of 1:25,000,
provided by the Brazilian Institute of Geography and Statistics -
IBGE, and orthophotos on the same scale. With the support of
this material were collected 23 control points for the
implementation of the adjustment of the scenes and another 21
points to verify the results obtained. The orthorectification was
performed at the PCI Geomatics OrthoEngine software version
10. To evaluate the results obtained by the geometric correction,
the bands were compared before and after the orthorectification,
and classified according to Standard Cartographic Accuracy -
PEC, according to current law in Brazil. The PEC is a statistical
indicator of dispersion on the 90% probability, which defines
the accuracy of cartographic works on a national scale. The
probability of 90% corresponds to 1.6449 times the standard
error.
After adjusting the image was carried out field work to identify
different classes of vegetation and the stages of conservation.
Some samples were selected. Were considered: Pasture - P,
Capoeira - S, Early Stage in Forest Conservation — F1, Forest
Conservation Internship in Secondary - F2 and Advanced
Internship in Forest Conservation - F3. Among the parameters
considered for this classification is the species diversity and
degree of canopy closure.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
Finally, after completion of the image processing , some curves
were created representing the spectral reflectance of the objects.
In this stage was is possible identify the different responses for
each class.
3. RESULTS AND DISCUSSION
The atmospheric correction enabled the improvement in spectral
response of the targets, especially in areas with vegetation
cover.
The results observed after the orthorectification of the scene
showed that the product meets the class B to a scale of 1:50,000
as indicated by PEC.
3.1 Vegetation cover
During the field work were initially identified Pasture samples
as seen in Figure 2. This class is very common, especially near
the roads.
Figure 2. Types of vegetation — Pasture in Duque de Caxias
city.
The Figure 3 highlights a sample collected to differentiate the
areas of capoeira vegetation. The field survey confirmed this
characterization, as well as, details to the biophysical
characteristics of the vegetation cover.
Figure 3. Types of vegetation - Capoeira
