coherence map creation are 15 lines and 3 columns. 
This corresponds with an area of about 60*60 
meter in the terrain. 
Figure 8 shows the coherence map that is created 
using conventional filtering and figure 9 the one 
that is created applying the procedure described in 
this paper. 
3. Conclusions 
The resolution of a coherence map can be increased 
using a combination of linear average filters instate 
of using a single average filter. In the combination, 
one of the filters is with the central sub-image pixel 
included and the other one without. The difference 
in coherence between the maps created using these 
filters is compared with a threshold. If the 
difference exceeds the threshold then the coherence 
that is created with the “complete” filter is assigned 
and otherwise the coherence from the normalized 
images is used. The high coherence of points with 
high backscattering values remains with this 
approach without influencing too much the 
coherence of neighboring points. The thematic 
information in the resulting coherence map is not 
reduced in the surrounding of strong scatterers. 
4. References 
Huurneman, G.C., Gens, R., and Broekema, L., 
1996. Thematic information extraction in a Neural 
Network Classification of Multi-Sensor data 
including Microwave Phase information. 
Proceedings ISPRS 1996, Vienna, Vol II-p170 
Touzi, R., Lopes, A., and Vachon, P.W., 1996 
Estimation of the coherence function for 
interferometric SAR applications, In: EUSAR'96, 
Koenigswinter, germany, 241-244 
Wegmuller, U and Werner, C.L, 1994, Analysis of 
interferometric land surface signatures. Procedings 
of PIERS'94, Noordwijk, The Netherlands, Paper 
Code 039. 
Zebker, H.A, Werner, C.L, Rosen, P.A and 
Hensley, S.., 1994, Accuracy of Topographic Maps 
Derived from ERS-1 Interferometric Radar., IEEE 
Transactions on Geoscience and Remote Sensing, 
Vol. 32 No. 4, July 1994. 
Intemational Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 
543