Mt. Hinokiboramaru N This black frame shows the range of
: Tokyo the study area of this paper.
e 0 500 1000 m
n ———-Aá'
This black frame shows the
range of a map in Fig-5.
EA EE SY AVA
M
ZZ
N
Mountain trai
=
EN Scriously-deteriorated areas
7777. Moderately-deteriorated areas
Fig-4 Results of the interpretation of the
aerial photograph's
E COE
= à 22) $ pa
S SHE vd
Fig-2 Study area extent of deterioration and the scale of topographical poin:
conditions. Fig-!
2. GEOMETRIC CORRECTION OF AN AERIAL 3. INTERPRETATION OF AERIAL po]
PHOTOGRAPH PHOTOGRAPHS easil
At first, geometric distortion of an aerial photograph Secondly, degrees of forest deterioration are
due to topographical unevenness is corrected(Fig-3) investigated using aerial photographs(Fig-4). The Fron
using DEM. Therefore, a relatively simple method has forest was classified into three categories; seriously- tree:
-been developed and its accuracy is examined. Basic deteriorated areas, moderately-deteriorated areas and whic
idea of this method is the same as the geometric ^ areas without deterioration. In the seriously-
correction using affine transformation. This method deteriorated areas, the ground surface can be seen even
however , can correct distortion by compensating from the air due to the collapse of trees, and in
positional errors due to the relative difference of | moderately-deteriorated areas, trees without canopies
elevation. Average positional error is approximately are found.
9m. It is concluded that this method has an satisfactory
accuracy for this research considering the spatial 4. GROUND SURVEY
In order to verify the interpretation results, a
ground survey is carried out. In this ground
survey, the degree of deterioration and
the percentage of dead tree, a tree species,
were examined at the twelve spots, and the
longitude and latitude of ground survey spots
are measured using Global Positioning
System (GPS). To make a measurement error
as small as possible, measuring was repeated
HPs La at least four times in the same spot, and a
Original data Corrected photograph mean was calculated. The point where the
variation of observation values was larger
Fig-3 An aerial photograph
714 International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998