International Archives of Photogrammetry and Remote Sensing, Vol. 32, Part 7-4-3 W6, Valladolid, Spain, 3-4 June, 1999 
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SENSOR FUSED IMAGES FOR VISUAL INTERPRETATION OF FOREST STAND BORDERS 
R. Fritz, I. Freeh, B. Koch, Chr. Ueffing 
Dept, of Remote Sensing and LIS, University of Freiburg, Tennenbacherstr. 4, 79106 Freiburg, Germany, 
feminfo@felis.uni-freiburg.de 
KEYWORDS: IHS-Transformation, Adaptive Image Fusion, Forest Stand Border Delineation, Quality Analysis. 
ABSTRACT 
In the last years forest cartography is changing from an analog to a digital generation and presentation. For this purpose, forest 
departments develop and implement Forest Geographic Information Systems. Till now, the actual stand borders are delineated based 
on B/W orthophotos. This procedure requires at least four processing steps to integrate stand delineations assessed during forest 
inventories into the final digital forest management map. Each step produces errors and makes the procedure of data integration 
labour- and cost-intensive. With the availability of high resolution satellite data, the use of such data for forest map production 
becomes feasible. Due to the information requirements, high spatial and spectral resolution is needed. The fusion of image data 
provides an opportunity to meet these requirements. Different fusion techniques have been tested, such as IHS-, PC- and Brovey- 
transformation to combine the spectral and spatial information of satellite data. All three sensor fusion methods show a visual 
improvement of the images by the synergy effect combining high spectral and spatial satellite data, whereby the IHS transformation 
showed best colour differentiation for visual interpretation. 
Due to the good performance of the IHS transformed images, the applicability of sensor fusion techniques for forest inventory 
mapping has been investigated with an IHS transformed product of Landsat TM and IRS-1C pan [IHS_TM]. This product was 
compared to an IHS transformed SPOT XS and PAN [IHS_SP], IRS-1C pan [Pan] alone, a B/W orthophoto [Ortho] and a simulated 
QuickBird image [Qsim] with lm resolution. The resulting image fusion products have been interpreted and digitized ‘on-screen’ by 
two persons in order to delineate stand borders. 
The comparative evaluation is performed in two steps: (1) measuring the visibility percentage of forest stand borders in reference to 
the official forest inventory maps and (2) calculation of quality measure criteria. The total length of stand borders in the test area is 
more than 40km. In every image product more than 70 % of stand borders have been detected, with IHS 72%, PAN 76% and 
simulated QUICK 85 % correspondence. 
Another tested approach was to combine Landsat TM and KVR-1000 (2m resolution) with different fusion techniques. In a first step, 
an adaptive image fusion (AIF) was calculated. In a second step, the resulting image was combined with the high resolution data, 
again with an IHS transformation. The output of this transformation shows very good results for visual interpretation and will be used 
as photorealistic background for tourist information systems. A precondition of this method is a very accurate rectification of the 
input data. Otherwise, it will provide poor results with a lot of artefacts. 
1. INTRODUCTION 
With further development of information technology the 
requirements of forest departments for using geographic 
information systems increased at the end of the 80s (Teuffel and 
Krebs, 1996). The result of this development was the 
implementation of Forest Geographic Information Systems. The 
forest cartography is changing from an analog to a digital 
generation and presentation. 
Parallel to the digital development in forest cartography, the 
geometric resolution of new generation of satellites is also 
increasing. The existing optical satellite systems (TM and 
SPOT) did not prove suitable for forest mapping applications in 
intensive and small plot forest conditions, as in Middle Europe. 
With the relatively low geometric resolution of the existing 
satellite systems, the complex conditions of the forest areas can 
not be mapped. Consequently, satellite data have not been 
implemented in forest map generation. 
With the availability of high resolution satellite data with up to 
6m in panchromatic band, the use of satellite data in the forest 
map preparation chain may be possible with the required map 
accuracy. 
The present research project on one hand verifies the potential 
of high resolution satellite data for digital forest map production 
and on the other demonstrates the application of sensor fusion 
techniques to combine the spectral and spatial information of 
satellite data.