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5. SUMMARY 
A new semi-empirical technique for the estimation of vegetation 
parameters from multispectral image data was proposed and 
tested with real data. By inverting physical radiative transfer 
models in combination with an empirical model agriculturally 
relevant vegetation parameters can be estimated given the grey 
value vector of the Daedalus scanner imagery. The inversion of 
models was conducted by a least squares adjustment in 
combination with simulated annealing. Four vegetation 
parameters leaf area index, chlorophyll content, specific dry 
matter, and specific water content have been selected for the 
inversion process. 
Ground control points are a necessary part of our inversion 
process and are used for a linear fitting of model-predicted grey 
values tó measured grey values. The goal is to use a minimum 
of ground control points to receive acceptable accuracies for the 
estimated vegetation parameters. Results show that by using at 
least one ground control point the accuracies are more or less 
independent of the number of ground control points. Using 
more than one point increases the robustness of the inversion 
process. In this case the grey values at ground control points 
should cover the whole range of grey values in the visible 
bands. If only one ground control point is used this point should 
lie near the center of the grey values range for acceptable 
accuracies and robustness. 
The influence of constant input parameters of the physical 
models on the accuracies has been investigated. Only the soil 
reflectance should be adjusted to the actual soil reflectance 
occurring at the investigated sites. All other constant parameters 
can be set to any values within the definition range. 
ACKNOWLEDGEMENT 
This project was financed since 1999 by GSF-National 
Research Center for Environment and Health in Munich and 
Chair for Photogrammetry and Remote Sensing at Technical 
University Munich. I would like to thank Hans Peschl, Robert 
Lanzl and Jan Ketzel for their support during the data 
acquisition campaigns in summers 2000/2001 as well as Prof. 
Dr.-Ing. Olaf Hellwich and Prof. Dr.-Ing. Heinrich Ebner for 
their fruitful comments. 
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