International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
  
sight of the buildings produced from digital images 
collected by digital cameras and by  softcopy 
photogrammetry technique "(Gruber et: Hal 1995). 
Afterward, these models can be included in a GIS such as 
Historical Asset Information and Management System 
and then published on the internet to share with citizens 
and other professionals (Ioannidis et. al., 2002). It could 
also be included into a Virtual Tourist Information 
System that is even supported by a vehicle navigation and 
tracking system (Malaka & Zipf, 2000). In this case, GPS 
comes into use. Not only this case, but also there is 
another place to use GPS in terrestrial photogrammetry 
especially in architectural and — archeological 
photogrammetric studies and works. This can be a similar 
way of use as being in GPS supported aerial 
photogrammetry. So, it is the determination of camera 
perspective center's coordinates. With only a difference, 
which is that the camera is not onboard a plane, just top 
of a digital camera few decimeters above from the land, 
on a tripod. This technique is also capable of providing 
fixed rotation angles of digital camera as well. 
Using above techniques we can have a very attractive 
system which is viable and can support itself. 
2. GPSSUPPORTED TERRESTRIAL 
PHOTOGRAMMETRY 
    
      
Figure 1: Removing GPS antenna from the 
levelled tribrach 
First of all, GPS can be used to determine the nation wide 
local coordinates of control points fixed on facades of 
any object that is subject to  photogrammetric 
measurement. At the first look, it can be said how GPS 
can be used for this purpose. There is a technique which 
is called as GPSSIT (GPS Virtual Station Technique) and 
was suggested by some researchers from Turkey (for 
more details, refer to the Corumluoglu’s paper 
(Corumluoglu et. al., 2003)). This technique uses GPS to 
determine the coordinates of reference center of any 
surveying devices without any extra hardware and costs 
nothing. Core of the technique depends on the use of a 
single tribrach for each device to be set up on a tripod. So 
what ever the device it is used, the technique needs only a 
small adaptor apparatus between triprach and the device 
to be used. For example, this technique was first used to 
determine the optical center of an EDM set up on a 
tripod. Therefore, it can also be used to determine the 
coordinates of a digital camera set up on a tripod as well. 
In the form of GPSSIT that utilizes EDM, the technique 
uses the combination of EDM and GPS antenna by the 
help of a leveled single tribrach (figure 1). Thus, the 
coordinates of optical center of EDM are able to be 
determined easily in the way of similar strategy and 
technique that have been being used successfully in GPS 
supported aerial photogrammetry, if it is recalled here 
(Ackermann, 1994, Corumluoglu, 1998). After the optical 
center coordinates of EDM are determined up in the air 
by GPS antenna using GPSSIT, coordinates of details and 
features on land and even the coordinates of the control 
points chosen on facades of an object, which is subject to 
photogrammetric processes, can be found out by referring 
the EDM measurements to the optical center of EDM 
defined by GPS. Here can generally be said, that GPSSIT 
can practically be used to determine the coordinates of 
control points chosen on the facades of any object in 
terrestrial photogrammetry. Each object to be evaluated 
photogrammetrically can then be described with respect 
to the others in a same reference coordinate system and 
land features and details surrounding the each object as 
well, even if these objects are far away kilometers from 
each other. Thus, it is being provided a unity of 
coordinate for all of the objects and control points in 
photogrammetric projects (figure 2). Even they can be 
produced in different times and easily be included in any 
previous photogrammetric project which was carried out 
by means of digital photogrammetry and GPSSIT. 
Es E»B 
  
  
  
Figure 2: Different locations for GPS supported 
terrestrial photogrammetry by GPSSIT 
and a unique reference system. 
There is one more thing that GPSSIT offers for terrestrial 
photogrammetry. It is the use of the point determined by 
GPS antenna on tribrach for a digital camera as well 
(figure 3). Thus, the camera perspective center is not any 
longer an unknown. Its coordinates are similarly 
determined by the GPS antenna as it is being in the case 
of EDM and especially in the case of GPS supported 
triangulation in aerial photogrammetry. This reduces the