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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part BS. Istanbul 2004
Nowadays. Total station has been widely used together with
digital camera in applications such as accident, archaeological
site survey, civil engineering survey as well as 3DGIS, building
reconstruction. But in most cases they have been used separately,
while total station is just used to achieve the 3D object
coordinates of control points for the following photogrammetric
process [Masataka Imura, etc., 2001; S. Ikeda etc., 2003]. Carl
Gravel presented a CAP (computer assisted photogrammetry)
system, which combines a total station with ordinary digital
camera and also offers corresponding software for processing
the data [Gravel C. etc., 1999]. Unlike his system, in PTSS
camera is fixed with telescope of total station instead of total
station so that camera can be rotate with the telescope. Field of
vision has been extended by rotation photos so that high
accuracy has been obtained.
Generally speaking, the technique of integration of total station
and digital camera is still under development. So when
proposing several problems which should be resolved for
further development of geoinformatics in one of his papers,
Shunji Murai said "Integration of total station and digital
camera for close range measurement: onsite processing for
triangulation with ground based control survey has been
developed. In future total station with digital camera should be
developed."[Shunji Murai, 2002] In this work our contribution
aims at providing a further step towards fully development and
wide application of this technique.
In the following, section 2 presents the system hardware,
photography method, Coordinates System, Collinear Equation,
Orientation Offset definition in detail. Then measurement
process and mode are introduced in section three. Experimental
results as well as accuracy analysis and sample applications are
shown in Section four and five respectively.
2 SYSTEM DESCRIPTION
2.1 Hardware
The hardware of PTSS includes metric digital camera, total
station and PDA (Personal Digital Assistant). As Fig.l shows,
metric digital camera is rigidly fixed on the telescope of total
station with a mechanical adapter and PDA, which is not shown
in the figure, is used to store measurement data and image index
and also control whole survey process of total station.
Metric digital
camera
x
ge b ye
Total station
Fig. 1 Hardware of PTSS
2.2 Coordinates System
In PTSS, three coordinate systems have been involved: ground
coordinate system(G-XYZ), total station coordinate system
(I-XYZ) and image space coordinate system (S-xyz) (see Fig.
2). Ground coordinate system is left-hand system. Total station
coordinate system and image space coordinate system are
right-hand system, but their orientation of coordinate axis is
different. Before calculation, coordinates system should be
transformed so that all calculation happens in same coordinate
system.
ZG
V
X r
X
G Yo
Ground coordinate system S
Zz
2;
Ys: image space
coordinate system
T Xr
Total station
coordinate system
Fig. 2 Coordinate systems
y
=
S0 X
Xo ;l X
Z
2.3 Definition of OFFSET
Image forming process of camera is a central projection defined
in image space coordinate system. The location and orientation
of central project in total station coordinate system can be
uniquely determined in terms of coordinate
AX olt Y nié Z so 9f projection center S in total station
coordinate system along with the angular orientation elements
of its space axis system in the total station axis system (Fig. 3).
The elements of angular orientation are commonly represented
by three independent angles ( (9g , C0, , Æ, ), which. along with
sr 7
X ME Yeo 5 Z so s
camera and total station.
is referred to as Orientation Offset between
2.4 Collinear Equation
In traditional photogrammetry, collinear equation is used to
describe the relationship between ground coordinate system and
image space coordinate system. But in PTSS a new system, total
station coordinate system is added. When an object point in total
station coordinate system is projected into an image point (x, y,