Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
Determination of spectral signatures of different forest damages 
from varying altitudes of multispectral scanner data 
A.Kadro 
Department of Photointerpretation and Remote Sensing, University of Freiburg, FR Germany 
ABSTRACT: Within the soope of the project "forest damage inventory with multispectral scanner data" at the De 
partment of Remote Sensing at the University of Freiburg, thematic mapper simulation data of different alti 
tudes was acquired. Five test areas vhich differ in rorphology, forest types and forest damage degree 
were sensed. For the investigation of the spectral signatures, reference panels were placed along the flying 
strip (size ca. 200 sqm) for the determination of the global radiation. The data were obtained from three al 
titudes (300, 1000, 3000 m) so that the spectral signatures could be determined in relation to the flight al 
titude . 
The scanner data of 300 m altitude enables the investigation of single trees. The data of higher altitudes only 
permit the investigation of trees or stands because of the larger pixel size. The same test areas have been 
used also for the investigation of spectral signatures of Landsat (TM) data. In this paper the results of the 
investigation are presented and discussed. 
1 INTRODUCTION 
According to many investigations in the laboratory and 
in situ measurements on healthy and damaged vegeta 
tion using radiometric measurement, it has been de 
termined that there are differences in the spectral 
reflectance signatures of objects especially in the 
visible, near and middle IR-regions of the electro 
magnetic spectrum (Kadro 1981). This has sparked us 
at the Department of Photogrammetry and Remote Sen 
sing of the Univ. of Freiburg to carry out an investi 
gation of computer determined spectral reflectance 
properties of forest damages with data collected from 
different altitudes above a large forest area (Kadro 
1984, 1985). 
For this purpose multispectral data were collected in 
July 1984 and Aug.1985 from 300 m, 1000 m and 3000 m 
above ground and TM data from landsat 5. The aircraft 
data were collected with the Bendix 11 channel multi 
spectral scanner (Table 1) modified by DFVLR/Ober 
pfaffenhofen to simulate the Thematic mapper in Land 
sat 5 (Table 2) . 
To determine the incident radiation (global radiation), 
reference panels were placed along the flying strip 
(size ca. 200 sqm). 
The data collected from the different altitudes have 
the following ground resolution or pixel size: 
Table 1. Spectral channels and wavelengths of the mo 
dified Bendix multispectral scanner. 
channel A nm 
AÀnm 
channel A nm 
A A nm 
2 
465 
50 
8 
720 
40 
3 
515 
50 
9 
815 
90 
4 
560 
40 
10 
1015 
90 
5 
600 
40 
5 TM 
1650 
200 
6 
640 
40 
7 TM 
2210 
270 
7 
680 
40 
11 
11000 
6000 
Table 2. Spectral channels and wavelengths of Landsat 
5 TM. 
channel A nm 
ftAnm 
channel A nm 
£>Xnm 
1 
485 
70 
5 
1650 
200 
2 
560 
80 
6 
11450 
2100 
3 
660 
60 
7 
2215 
270 
4 
830 
140 
0,75 
X 
0,75 
m 
at 
300 m altitude 
2,5 
X 
2,5 
m 
at 
1000 m altitude 
7,5 
X 
7,5 
m 
at 
3000 m altitude 
30 
X 
30 
m 
at 
705 km altitude (Landsat 5 TM) 
It is possible to investigate the spectral signatures 
of single trees frcm the data collected at 300 m al 
titude, but data iron other altitudes make it possible 
to investigate only a group of trees or stands. The 
location of the test site is in the Black forest area 
of south-west Germany and contains different exposures 
and diverse types of forest stands with different de 
grees of damages. The forest stands are mostly the 
conifers of spruce and fir or these two mixed. 
2 METHODOLOGY 
The basic physical quantity characterizes the spectral 
reflectance properties of the vegetation in the esti 
mated spectral reflectance factor R (A) defined by 
the equation (Kriebel 1978): 
JL L. (j9 f ) cosa^ do- L> () 
. '4rx r Xr r, * r *r r Ar r 
R (A) = ^y— 
AW / cos 3 dAr L 
Jar A w 
where: 
R(A) = spectral reflectance factor 
Li = value for the reflected radiance of a natural 
Ar 
target 
jr = zenith angle of the reflection 
r = azimuth angle of the reflection 
Sir = solid angle 
*r,w = reflected radiance of the Lambertian reflec 
tor (reference panel) 
In this work the multispectral scanner was used to 
collect information on the spectral radiance of the 
vegetation and on the incident radiation of the re 
ference panel vhich was placed along the flight strip. 
The spectral reflectance factor is, for practical 
purposes, estimated in this case as follows: