International Archives of Photogrammetry and Remote Sensing, Vol. 32, Part 7-4-3 W6, Valladolid, Spain, 3-4 June, 1999 
155 
Year 
Acquisition date of remote sensing 
imagery 
Ground truth information 
SPOT 
Landsat 5-TM 
(Scene 196-23) 
Information from the Environmental Protection 
Agency - district Diepholz 
1984 
25.04.1984 
aerial photographs 1984 
1986 
17.05.1986 
1987 
07.07.1987 
CIR- aerial photographs 26 May 1987 
1988 
biotope type mapping Diepholz 1988/89 
1990 
15.07.1990 
1991 
13.04.1991 
biotope type mapping Bassum 1991 
1992 
biotope type mapping Bamstorf 1992 
1994 
18.02.1994 
24.06.1994 
biotope type mapping Bruchhausen-Vilsen 1994 
26.07.1994 
biotope type mapping Bruchhausen-Vilsen 1994 
1995 
24.04.1995 
27.06.1995 
Table 1. Overview of the current database. The light grey rows show the most relevant data. 
3. GROUND TRUTH 
To yield acceptable classification results, training data is 
needed. Training statistics for all spectral classes constituting 
each information class have to be computed. A supervised 
classification requires a thorough knowledge of the geographic 
area. Most importantly, the quality of the training process 
determines the success of the classification stage and, therefore, 
the value of the information generated from the entire 
classification effort. The overall objective of the training 
process is to assemble a set of statistics that describe the 
spectral response pattern for each landcover type to be classified 
in an image (Lillesand and Kiefer, 1987). 
An objective mapping key for ground truth measurements was 
generated. This mapping key is adapted to the special biotope 
mapping key in Lower Saxony with respect to § 28a NNatG 
(Lower Saxony's Environmental Protection Statutes) 
(Drachenfels, 1994). Moreover, it was adjusted to the German 
ATKIS object catalogue. For selected queries and overlay 
analysis, these mapped test areas were transformed to separate 
GIS layers in Arclnfo® format. 
Figure 1 shows the total test area (which corresponds to the 
district boundary of Diepholz) and the 4 ground truth locations. 
The box demonstrates the exact dimension of the central 
LandsatTM scene 196-23. 
Fig. 1. Overview of the total test area and ground truth areas. The box shows the outline of Landsat TM scene 196-23.