n. The 
bution 
'erages 
dicate 
zes the 
w and 
ctional 
center 
shows 
ith the 
SPECTRAL BEHAVIOUR ANALYSIS OF Au AND Cu-Pb-Zn OREBODIES USING 
CONVOLUTIONAL CORRELATION OF TM-LANDSAT DATA 
Albano Henrique de Araûjo 
Osmar Abflio de Carvalho Jr. 
INFOSAT - Sensoriamento Remoto 
SQS Qd. 01, Bloco B 
Ediffcio Maristela, sala 1214 
70000-000 - Brasflia - DF 
ISPRS Commission VII / Working Ciroup 4 
ABSTRACT 
In this paper we investigate spectral behaviour of Au and Cu-Pb-Zn orebodies in TM-Landsat data using 
convolutional correlation. This technique is implemented by the determination of local correlation 
coefficient for square windows (if possible) with 25 to 49 pixels and attribution of this value to the center 
of the window like a convolutional (latu sensu) filter. The window is displaced with a small step often 
less than 3 pixels. Thus, this technique indicates the areas where the correlation coefficients varies locally 
and can be used in two ways; (i) based on the general spectral behaviour of the orebodies we can preview 
the changes in the correlation for the TM bands and (ii) select the pairs of bands where a specific orebody 
will be enhanced. On the other hand, based on the probably position of the orebody, we can determine 
which pairs of bands detects the presence of the occurrence. We develop a case study in the Guarinos 
greestone-belt area, with Au occurrences, and Palmeirópolis volcano-sedimentar sequence, with Cu-Pb- 
Zn orebodies. The application of the technique indicates that the best results are obtained when pairs of 
bands have original correlation coefficients smaller than 30% or greater than 70% for total area used, due 
to the possibility of discriminating correlated and non-correlated orebodies respectively. In the study 
areas, the technique showed excellent results discriminating the most adequate pair of bands to identify 
known orebodies and indicate new occurrences. 
057