International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004 
  
Some errors in rolls, runs, photos and counters number are 
detected. The approximated photo centre coordinates (APCC) 
was made by hand. At time of photography, no aerial camera 
was equipped with GPS or INS. In the fact, this APCC could 
be wrong for some miles (fig. 1). 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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Fig.1. Overview of the project location 
a square is map sheet 1:50.000 (15' x 15) 
From the pre-selected photos, a paper copy will be made. The 
paper copy will be then layout to get the optimal combination 
between photogrammetry quality and minimum cost. The 
Potential GCP placement will be done simultaneously on the 
layout, and thereafter the layout will be snapshot to have good 
documentation. 
1.3 The Selection of Potential GCP 
A big problem for this project is the fact that: (1) there a large 
number of aerial photos; (2) the photos are heterogeneous; (3) 
the photos are older than 5 years; (4) there is no premarked 
ground control on photos; (5) there is no kinematics-GPS on 
board of photo-position for aerial triangulation. In addition, 
the post GCP-survey would be very hard. The problem is 
focused also to identify the place on photographs to the current 
situation and to get the place. 
The problem to make post-GCP for successive aerial 
triangulation is to identify the suitable points. These natural 
GCP should fulfil at least 4 requirement: (1) the point must be 
good geometrically distributed, (2) the point must be clear 
identifiable on photographs, (3) the point could be found again 
now — although gap of more than 10 years, (4) the point must 
be accessible — partially using helicopter. Points (1) and (2) 
will be decided by photogrammetrist on the office. Point (3) 
will be decided by photogrammetry-surveyor on field. In case 
of survey by helicopter, point (4) will be decided by pilots. 
For one full sheet (ca. 160 photos) at least nine GCP must be 
found and some others must be selected as reserves. In the 
reality, this job is often very difficult due to the low quality of 
the photos or the fact of the objects (just jungle without 
texture, or texture but without access possibility (fig.3). 
  
    
   
  
  
  
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Fig. 2. Lay outing of Photo and Planning GCP location 
1.4 GCP Survey using Helicopter 
For GCP survey using helicopter, a good plan must be 
established. Due to the difficult area, some logistic base 
camps and fuel points must be selected. Base camp is 
normally place where there is minimal a house which could be 
used for several day for crew. Important is water. Food should 
be brought by our self. Electricity must be also generated by 
own generator. Fuel to the fuel point must be transported by 
boats or land vehicle. This fuel point must be place where 
helicopter can land, although it is not a helipad. 
During the survey, all necessary equipment must be taken to 
the field, including some laptop computers, also CD writer for 
backup, printer, GPS navigator, digital camera, etc. For 
communication, satellite hand phone will be used. 
Unfortunately, the data channel is not yet established, so data 
store to the office could not be done. Consequently, a special 
procedure is applied to guarantee that in all data is saved. 
Data is copied to two laptops, USB-Hard disk, and some CD. 
Regularly, the CD is sent by snail-mail to the office if post 
office is found. The whole campaign is about 60 days, and we 
don't know what happened during these days. To avoid data 
loss if accident is occurred, during moving, laptops, USB-HD 
and CD bearer should not be in same helicopter. The 
campaign will be carried out by three helicopters. 
Helicopter operation is rather expensive, but in almost points 
in the jungle of Kalimantan, it is the only way to get the points. 
The more serious problem is to identify the point, since the 
photographs is made about 10 years ago. In Kalimantan 
jungle, the most accurate point for ground controls is manmade 
objects like bridge or county-office house. Once it is created, a 
renovation is rather seldom. The second accurate point is 
Mouth River to another river. However, sedimentation or 
crosion could change this landscape. The third and last 
alternative is logging road or logging airstrips. Some of them 
are changed, leaved already or many new are created, so 
identifying is very difficult.