GPS Satellite 
FM radio station 
Figure 4 The Composition of the System 
Figure 2 Scenery at Former Plotting 
It is necessary to measure control points for geometric correction. 
Control points are selected on terrain feature points. Control 
points are measured using GPS. To get higher precision, we 
attempt to measure control points using DGPS whose differential 
data is offered from service by FM multi-channel broadcasting 
Also, it is necessary to transform coordinates of control points 
from WGS-84 coordinate system to final result’s coordinate 
system. 
And field surveyors input field investigation data on image data 
with laptop computer instead of drawing on photographs with ink 
pen. Also, at the time field surveyors input investigation data, 
geometric correction is refrained to heighten geometric precision. 
Figure 3 shows procedure of this method. Also, Figure 4 shows 
the composition of the system. 
I Plotting and Editing of DM • I 
(In a Room ) I 
Do 
Loop 
For 
Necees 
sary 
Figure 3 Processing Procedure 
3 GEOMETRIC CORRECTION 
3.1 Affine Transformation Using TIN-Model 
Originally, Affine transformation using TIN-model was proposed 
to correct historical map. 
Usually, Affine transformation and Helmart transformation is 
used for geometric correction of image. But there are some 
positional differences at control points with these transformations. 
On the other hand, there is no positional difference at control 
points with Affine transformation using TIN-model. Since it is 
P2-1-2