Bacchi, Gustavo Sanches 
  
Comparative analysis of land cover maps obtained from vertical aerial photographs 
and panchromatic Spot images. 
Gustavo Sanches BACCHI; Marcos RODRIGUES; José Alberto QUINTANILHA; Diana Sarita HAMBURGER 
University of Sáo Paulo, Brazil 
Laboratório de Geoprocessamento, Escola Politécnica 
gubacchi@usp.br 
marcos@cartaconsultoria.com.br 
jaquinta@usp.br 
dianash@usp.br 
Technical Commission TC VII-1 
KEY WORDS: Land use/Land cover, Classification, Remote sensing, SPOT, Watersheds. 
ABSTRACT 
The land cover map is one of the most important spatial data in many geographical information systems applications. 
Most of the environmental analyses use land cover and land use maps (CAHILL et al., 1995). This study focuses on the 
integrated watershed land cover planning as a basis to water quality assurance to be used by local governments. 
Thinking on one of the main problems suffered by local governments and small watershed associations, the resource 
scarceness, this study made a comparison between two remote sensing sources in a low cost digital land cover 
classification. 
1 INTRODUCTION 
The regional watershed planning approach of most of the Brazilian towns are characterized by shortage of the basic 
data. Without any doubt, this data privation is one of the most important restrictions for the watershed planning 
developments and land cover zoning implementation. Because of that, the proposal and the use of low cost 
methodologies that could increase the viability of the basic data acquisition for the planners’ demand are important 
tasks in the regional scenario. 
The regional scenario could be described as the decision makers that work in small watershed planning and frequently 
have scarceness of resources to develop their planning tasks. In this context, the optimization of the resources was the 
main approach of the present study, and this philosophy must be remembered at the employed classification method 
analysis. With this approach, the method adopted in this study was based in the panchromatic image classification and 
aerial photographs, in order to evaluate the degree of difficulty to obtain the land cover map. Also because of this 
approach, one of the main objectives of this study was to identify, between two sources of digital remote sensing data 
sources, the most adequate for the regional scenario. 
2 LAND COVER MAP GENERATION METHODOLOGY 
2.1 The remote sensing data sources analyzed 
The present study used a vertical aerial photograph which was obtained in a 1:25.000 scale. This photograph was 
converted for the digital environment by a 600 dpi optical scanner device. The other source used was an HRV Spot 
panchromatic satellite image (K716/J397) obtained ten months after the photogrammetric flight over the Ibaté-Mirim 
watershed. This watershed is one of the main water sources for urban supply of the Aracariguama town situated in the 
state of Sáo Paulo, southeast of Brazil. 
Since both remote sensing data have different spatial resolutions, they were submitted to a compatibilization process to 
enable the accuracy analysis described later on. Both of the digital remote sensing sources were imported in to the 
Environment for Visualizing Images — ENVI (RESEARCH SYSTEMS INC., 1997) for digital processing 
(RICHARDS, 1994). 
  
98 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.