THE METHOD OF Field INVESTIGATIONS USING DIGITAL IMAGE 
Toshiaki Taguchi, Kosuke Tsuru 
Air & Space photogrammetry Office, Aero Asahi Co. 
Japan 
Toshiaki.Taguchi@aeroasahi-tc.co.jp 
Hirofumi Chikatsu 
Faculty of Science and Engineering 
Tokyo Denki University 
Japan 
Commission V, Working Group V/I 
KEY WORDS: Digital Mapping, Field Investigation, DGPS, TIN-Model, Geometric Correction 
ABSTRACT 
It has been already passed more than ten years since the digital mapping started in Japan. During this period, the system was improved 
so as to construct the fundamental system in the development of data structurelization and transformation of traditional mapping into the 
standard digital mapping. However, these processes are just only the later half of the whole process of digital mapping. Hereafter, it 
becomes necessary to digitalize process of leveling, control point survey and field reconnaissance survey etc. Especially in the case of 
field investigation, almost all expressions concerning the Digital Mapping are included in the investigation results. So, if these 
investigation results can be directly matched with digital mapping, the system to create Digital Mapping will be much more efficient. 
In the present paper, the system to collect the field by using laptop computer with FM wave D-GPS system is installed is explained. 
This system puts points of air photograph’s image data on same points of ground coordinates measured by D-GPS using differential 
information service by FM multi-channel broadcasting. This system generates TIN-model from these points and image is geometrically 
corrected by each triangle. So, it is able to improve positional precision of image without orthoprojector or results of aerial triangle 
survey. And, the results of field investigations are digitized on these images. Operators can input map symbols or cartographic notations 
directly and DM data can be checked with field investigation results without compare with aerial photographs. 
Also, we tried the method to acquiring the coordinates of the objects that were not shown on the aerial photographs. 
1 INTRODUCTION 
Usually, operators get mapping data with precious position using 
stereo photo model to create DM (Digital Mapping). This process 
called as plotting is carried out in a room. But it’s impossible to 
acquire all of DM data using only photographs. Following data 
are necessary to investigate on the field. 
( 1 ) Objects which is hidden in shadow. 
( 2 ) Objects which is difficult to specify by photo-interpretation. 
( 3 ) Symbols for building classification or vegitation 
classification. 
(4 ) Cartographic notations. 
In formerly field investigation, first, it is necessary to remake 
photographs on same scale of final result map. Next, field 
surveyors go to field and draw reconnaissance result on remade 
photographs with ink pen. (Figure 1) 
But, this method has some weak points. 
( 1 ) Because field surveyors draw results on photographs, it is 
difficult to correct mistakes. Also, ink is sometimes blotted 
influenced by sweat or rain. 
( 2 ) Operators refer field reconnaissance results on plotting or 
editing. On this time, it takes much labor to match DM data 
with remade photographs. (Figure 2) 
( 3 ) Sometimes results aren’t inputted on DM data. 
(4 ) It is troublesome to carry or to store remade photographs 
after field reconnaissance survey. 
On the other hand, if these field investigation results can be 
matched with digital mapping process, the system for creating 
Digital Mapping will be much more efficient. 
P2- 
Figure 1 Former Field Investigation Photographs 
2 DIGITAL FIELD INVESTIGATION 
In this method, first digital image data of field are prepared 
instead of remaking photographs. Next, field surveyors go to field 
with laptop computer and GPS receiver. Then, digital image is 
geometric corrected on field. 
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