THE USE OF A TEMPORAL ANALYSIS OF C.I.R. IMAGES FOR THE 
EVALUATION OF THE VEGETATION DAMAGE IN INDUSTRIAL AREAS. 
DAELS L. and ANTROP M. Seminar for Regional GEography. 
Center for Remote Sensing - State 
University of Ghent (Belgium) 
1. Introduction 
It is generally accepted that C.I.R. aerial photography is 
an important and useful document for the detection of "stress" 
or "damage" conditions of the vegetation. 
Obviously a temporal analysis of these documents will be ne- 
cessary to acquire a dynamical understanding of the environ- 
mental conditions. 
A single interpretation is the registration of one specific 
moment and reveals little about environmental processes. 
A temporal analysis allows the study of the evolution of the 
environmental phenomena which is vital to understand hidden 
forces or causes. But a temporal analysis increases the in- 
terpretation difficulties and errors for the quality of 
photographs taken at a different period is never the same. 
The reason why such interpretation is often disappointing or 
even unreliable is treefold : 
- a neglect to take into account the influence of the 
terrain conditions upon the final image-formation. These 
terrain conditions may be split up into two groups ; the en- 
vironmental conditions and the reflectance characteristics ; 
- a lack of knowledge of the photographic and geometric 
aspects of the information transfer ; 
- incautious comparisons between the interpretations of 
a different datum. 
This discussion will be restricted to the use of trees as 
indicators for the monitoring of the environmental quality 
control. Trees are used as indicators because they are more 
permanent than cropland or grassland and for a temporal ana- 
lysis they can be used during several years.