6. FIELD COMPLETION SURVEY WITH GPS 
Since plottability of SPOT image is rather 
limi tted, field completion survey to 
compensate SPOT image plotting should be 
inevitable. However, the more field 
completion survey is necessary the less 
economical advantage of SPOT mapping is 
expected. Therefore, tt is necessary to 
develop practical and economical method 
for field completion survey. 
As for topographic mapping. linear 
features as principal roads and railways 
are very important but relatively 
difficult to be plotted. Therefore, 
practical field completion survey method 
for linear features. using GPS were 
studi ed. 
6.1 Concept of field completion with GPS 
Ihe basic idea of this method is such that 
a vehicle equipped with GPS antenna on the 
roof is driven on a road to be plotted. 
Road shape is to be plotted. from. the. GPS 
observed positions. 
may show some 
Independent posi ti oning 
hundred meter error. However, 
differential point positioning gives 
sufficient accuracy for medium scale 
mapping. Therefore, synchronized 
observation of a fixed point and a vehicle 
was executed. 
6.2 Experiment and result 
vehicle was driven on a 
another GPS was set on a 
triangulation point. Three dimensional 
coordinates were observed and recorded 
every one second. Then road shape was 
drawn from observed points and compared 
with a topographic map. 
GPS equipped 
highway while 
Figure 6-1 and 6-2 show the GPS observed 
practical field completion survey 
compensating SPOT image plotting. 
7. MANUAL FOR SPOT IMAGE INTERPRETATION 
Image interpretation is very important to 
make . topographic: maps using SPOT . data. 
SPOT image appears quite different from 
aerial photographs. Therefore, new 
instruction for interpretation suitable 
for SPOT data should be established. 
In order to make use for training of SPOT 
interpretation technique, SPOT image 
examples of certain ground objects were 
collected and compiled as training cards 
with aerial photos, maps and descriptions 
of key points for interpretation. 
7.1 Interpretation training cards 
An interpretation training card was 
prepared as one card for one item. It.is 
composed of 1:100,000 scale  SPOT.-stereo 
images of multi-spectral image on the left 
and panchromatic image on the right, as 
well as 1:60.000 aerial photo pair, 
1:4100,000 scale topographic map and 
comments, key points with ancillary data. 
Subject items were selected from the items 
of the Manual Technico de Conveciones 
Topograficas which is commonly used in 
Latin American countries. 32 cards were 
prepared. in total. in this study. 
8. SPOT MAPPING SPECIFICATION 
As the result of this study the Standard 
Procedure and Specification of Topographic 
Mapping using SPOT imagery was proposed. 
This specification -was compiled as an 
addi ti on to the Overseas Mapping 
Specification of Japan International 
Cooperation Agency for the use of Japanese 
  
  
point tracing and the corresponding map technology transfer program. 
draft... plotted from | aerial photographs 
respectively. The document is devided into three 
chapters as follows. 
The planimetric position well satisfies 
the specification of medium scale mapping. (1) Topographic mapping using satellite 
This method needs very short time for data. 
surveying because it is executed just by 
driving on a target road. Therefore, this This is expected to be applied for 
method should be able to be used as 1:100,000 scale topographic mapping or 
smaller. 
ON 
% 
= N NN. 
N 
N 
  
  
  
  
  
  
Figure 6-1 Trace of GPS outputs 
Figure 6-2 Aerial photogrammetric plotting