DIGITAL TERRESTRIAL PHOTOGRAMMETRY
WITH PHOTO TOTAL STATION
Zuxun Zhang“, Shunyi Zheng", Zongqian Zhan*
? School of Remote Sensing Information Engineering, Wuhan University, 129 Luoyu Road, Wuhan 430079, China
zx7hang(@supresoft.com.cn
syzheng(@263.net 77q09@263.net
5 gut JU 7(«
KEY WORDS: Digital terrestrial photogrammetry, Photo total station system (PTSS), Short baseline, Multi image matching, DTM
generation
ABSTRACT:
Terrestrial photogrammetry is engaged in measurement, contour delineation or 3D reconstruction with photos captured by a camera
located on the ground. Terrestrial photogrammetry has gained wide applications in many fields such as 3D building reconstruction,
heritage protection and so on. In this paper, a new instrument named photo total station system has been adopted and meanwhile based
on this new instrument, a flexible and efficient digital terrestrial photogrammetry method has been developed. Photo Total Station
System (PTSS) is a completely novel surveying system, which installs metric digital camera on total station to compose an integration
system together with digital photogrammetry software. PTSS takes full advantages of mature digital photogrammetry techniques and
accurate total station survey method and provides the benefits of both systems, while minimizing their shortcomings. The whole
process of digital terrestrial photogrammetry includes two stages: field survey and indoor photogrammetric processing. Depends on
specific measurement condition and requirement, three measurement modes can be selected to use so that the whole measurement
process can be very flexible. After field survey, all measurement data including images are processed by attached photogrammetry
software whose unique characteristics are presented in the paper: such as multi images based image matching (short base) are used
instead of stereo based one in the conventional photogrammetry; using so called control bars setting near the camera instead of regular
control points — a real non-contact measuring method can be implemented so that control points around or on the measured object can
be reduced or completely unnecessary. With this technique, DTM and contour generation, volume measurement and 3D modeling all
can be completed. The method proposed in this paper has been used in several measurement sessions. The results show its great
potential in digital terrestrial photogrammetry.
I INTRODUCTION
Terrestrial photogrammetry is engaged in measurement, contour
delineation or 3D reconstruction with photos captured by a
camera located on the ground. During past few years, with the
rapid development of digital photogrammetry techniques and
the availability of case-using, focusable and relatively cheap
digital cameras, the method and device used in terrestrial
photogrammetry also changed greatly. General speaking, digital
techniques become mainstream and efficiency has been greatly
improved. At same time, terrestrial photogrammetry has gained
wide applications in many fields such as 3D building
reconstruction, heritage protection and so on.
However in spite of great development of traditional terrestrial
photogrammetry over the past years, it is still necessary to set
some control points around the objects to be measured[Feng
wenhao, 2001]. It is well known that setting control points
around the objects is a very time-consuming and
labour-intensive job. So in fact photogrammetrists’ dream of
“non-contact measurement” is still on its way.
On the other hand, although widely accepted as an accurate
surveying method, total station survey still suffers from a
number of weaknesses: Firstly, total station does not mean total
survey. It is impossible to record an absolute survey of all the
features within a given area. It would be time-consuming and
pointless to record every individual brick in a wall, for example.
Secondly, many features such as line segments on the buildings
can not been fully used during measurement and however,
sometimes they are important to reconstruct the object to be
measured.
Based on these considerations above, this paper presents a
completely novel surveying system, named Photo Total Station
System (PTSS), which installs metric digital camera on the
telescope of a total station to compose an integration system
together with digital photogrammetry softwarc. In such system,
metric digital camera and total station are rigidly connected with
a mechanical adapter. During measurement with PTSS, firstly
traversing is complemented through total station and total
station is also used to measure object coordinates of necessary
control points on the control bar (board) near the traversing
point, which are mainly used to calibrate the off-set parameters
of the camera related to the total station. Meanwhile, at cach
traverse point photos are taken by metric digital camera. While
photographing, camera can rotate with telescope of total station
to take scanning photos whose corresponding orientations are
observed from total station. Finally measurement data and
images are processed by advanced digital photogrammetry
software and entire measurement is completed. lt can be scen
from the process of measurement that PTSS takes full
advantages of mature digital photogrammetry techniques and
accurate total station survey method and provides the benefits of
both systems, while minimizing their shortcomings.
The combination of camera and theodolite or total station can be
traced to many years ago. During 1970's, to perform terrestrial
photography, terrestrial camera was connected with a theodilite
to compose a system named phototheodilite. Different
phototheodilites include Zeiss Jena 19/1318 and the
Chinese-madeDJS/1318-1, Wild P30, P31, P32, the Zeiss Jena
UMK, and the Zeiss(Opton) TMK, etc[ Wang Zhizhuo, 1979; Li
Deren cte., 1992]. These instruments went to the end as
photogrammetry evolved from analogue and analytical stage
into digital cra.
During 1980s, it seemed likely that motorized theodilites with
CCD camera fitted to their telescope would be able to supercede
photogrammetric techniques in many industrial situations. They
could provide real-time read-outs of coordinates on industrial
targets. Afler a brief period of popularity their bulk, cost and
relative slowness compared to digital cameras saw their demise
[K.B. Atkinson, 1996].
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