2.2 New applications of 3D digital maps 
2.2.1 New mapping compilers with DTM(Digital 
Terrain Modelling) 
New mapping compilers should be responsible 
not only for ordinary digital mapping of 
general topographical maps but also for 
specified purpose mapping in different 
fields. 
Graphical features of digital mapping are 
freely processed within the environment of 
3D CAD (AutoCAD) for the following 
applications. 
1) Fundamental planning map or general 
purpose map 
2)«Structured data for GIS 
3) Overlay or Superimposition of photomap 
on linemap 
4) Basic graphical data for designing in 
civil and architectural engineering 
applications. 
For most potential applications of digital 
mapping,we can afford digital data based on 
digital terrain modelling method,especially 
triangulated terrain modelling for precise 
terrain presentation and designing. 
Photogrammetrists have played the major 
roles in analogue map production based on 
the classic procedures,such as aerial 
triangulation and photogrammetric 
orientation and compilation.3D CAD and GIS 
have reduced and replaced photogrammetric 
procedures with computer assisted commands. 
2.2.2 Digital Terrain Modelling for 
Engineering Design 
Since the beginning of map production using 
analytical plotters,we have tried many 
approaches in using DTM techniques in real 
time mode on photogrammetric stereoplotters. 
Photogrammetrists in Japan have been asked 
to produce the current status maps and 3D 
terrain models as soon as possible following 
natural disasters,such as floods,land slides 
and volcanic eruptions. 
Aero triangulations,3D data acquisition 
with contours and grid measurements were 
done successfully.However final presentation 
of the results have not yet been modernized 
for many years.Recently we combined data 
acquisition with DTM software on the same PC 
display in a success project following 
Mt.Unzen's eruption in 1991. 
In this context, all the planimetric 
features situated in the down stream areas 
of lava flow were digitized in 3D format in 
MAPCAD environment.They were then combined 
with 25-meter contours manually drawn in 
MAPCAD environment.Lava flow area itself was 
covered by 50-meter square grid DTM 
generated from this contours by PC-AutoCAD 
based GWN-DTM software(Photo 2.3).In this 
study,we also have developed a MAPCAD/Volume 
module which has adopted a dedicated 
conversion approach to compute lava volumes 
directly from contours.Using the same data 
set,performance of this module has been 
evaluated against the conventional procedure 
of computing with prismoidal formula via TTM 
as followed by GWN-DTM software .Tt was 
found that volumes computed from different 
approaches were comparable to each other 
with the difference of only 0.5%.However it 
was noted that the computation time and 
required data storage were substantially 
less in the case of dedicated approach,i.e. 
in the order of 1:8 and 1:3 respectively for 
this particular study. 
LT 
M M NE RAC ES CCC DI T 
  
Photo 2.7 Terrain Modelling in Mt.Unzen 
Case Study 
2.3 GPS Surveying,CAD GLOBE and Car 
navigaton Mapping 
For many years we have been investigating 
the applications of GPS surveying in our 
digital mapping projects.Based on our 
experiences with 3D CAD,we have created 
globe ellipsoids within the AutoCAD 
environment ,and called this methodological 
concept CAD GLOBE.As further applications of 
new digital mapping technology,we are 
developing a combined system of CAD GLOBE 
with projected maps on the same display of 
the CAD system (Figure 2.2). 
  
  
  
  
  
  
  
  
Figure 2.2 CAD GLOBE with Projected map 
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