Quadros, Clécio José Lopes de 
  
  
Samples Points Location 
  
Figure 2. Sampling mesh and geodetic landmark location 
Finally, the data were analyzed at GIS Spans. With the data of altimetry it was generated a digital 
model of elevation by the method of triangulation weighted average of Z-values. This surface model applies a 
weight inversely proportional to the distance of the center of the quad cell from the three vertices of the plane in 
the TIN. The filtering policy used was the maximum Z-value/Location, that determines the maximum Z-value 
and its location. Due to the little altimetric variation (0.78 a 3.85m) it was restricted to 5 classes of altimetry, 
being this posteriori converted to the format raster with spatial resolution of 6.4 meters. It was also applied a 
filter of Gaussian convolution 3x3. With the morphological forms information it was generated a thematic map 
utilizing the Thiessen method of polygons (Voronoi) with a resolution of 6,4 meters. Thiessen polygons contain 
only a single point, and have the useful property that any location within a polygon is closer (in Euclidean 
distance) to the associated point to any of the neighboring points (Bonham-Carter, 1994). 
5. RESULTS AND DISCUSSION 
Figure 3 shows the digital elevation model, where it is possible to observe that the highest altitudes are 
shown represented by the portion further from the estuary mouth and by strips of high altimetrics parallel to the 
coastline located both at the system of dune ridges as at the system of inner ridges. The altitudes diminish with 
the proximity of the mouth of the estuary being possible to observe the smallest altitudes on the portion of the 
beach ridge that is almost inside the estuary. This occurs, according to Duarte & Lessa (1996), due to the almost 
null incidence of waves on the inner part of the estuary in relation to the portion facing the open sea, fact that 
impedes the elevation of the terraces because of the low wave incidence. 
  
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International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.