ESTABLISHMENT OF CONTROL POINTS FOR DIGITAL
PHOTOGRAMMETRY TO ARCHIVE 3D MODEL OF RELICS
Yuta YAMAMOTO*, Jong-Hyeok JEONG** and Masataka TAKAGI***Infrastructure Systems Engineering, Kochi University of Technology,
Kami-shi, Kochi, 782-8502, Japan*105523m@gs.kochi-tech.ac.jp** jeong.jong-hyeok@kochi-tech.ac.jp*** takagi.masataka@kochi-tech.ac.jp

KEY WORDS: Photogrammetry
ABSTRACT: In a surveying of ruins, many hangovers must be quickly archived as digital
data. For example, a hundred pieces of hangovers are extracted a day in Dederiyeh Cave, Syria.
The detail must be recorded in each change scene for the archeologist. Digital photogrammetryis very efficient for 3D modeling. In this study, control frame is suggested to improve efficiency
of digital photogrammetory. Control frame was based on polygon shape. Target of control point
was located at apex of the polygon. This control frame will be efficient to setup control point.
When the shape of control frame was fixed always, it is not necessary to measure 3D
coordinates of all control points. Control frame was tried to design. 134,594 combination ofcontrol point were calculated. However, critical combination pattern was not found. Systematic
analysis will be required to find optimum special distribution of control point.

1. BACKGROUND
Today, surveying technology is needed in archeology field. Authors joined archeologicalexcavation investigation as surveyor. Many hangovers were measured in Dederiyeh Cave, Syria.
A lot of 3D models of the hangovers were built. Figure 1 showed example 3D model of one
hangover. Building 3D model spent much time because of control point measurement.
Archeologist can't excavated when the photogrammetry was carried out. In the photogrammetry,some control points must be setup. The control points were measured 3D coordinates by total
station accurately. This setup and measuring control points must be carried out many times when
the hangovers were appeared. Therefore, quick setup and quick measurement of control points isrequired.

Figure 1: 3D Model of One Hangover by Topcon PI3000

In this study, control frame was tried to designed. Control frame was based on polygon shape.
Target of control point was located at apex of the polygon. This control frame will be efficient tosetup control point. When the shape of control frame was fixed always, it is not necessary tomeasure 3D coordinates of all control points.

2. OBJECTIVESIn order to design control frame, an optimum spatial distribution of control point must be found.
Therefore, 24 control points were measured. These control points were located randomly. And 6
control points were selected for exterior orientation. There are 134,596 combinations to select 6
points from 24 control points.
In each combination, error of exterior orientation will calculated. The error means distance
between transformed coordinate by the orientation and true coordinate at validation point. Thevalidation point was established at the center in 24 control points.
In 134,586t combinations, the optimum combination will be found by evaluation of the error,
control frame will be designed.

3. METHODOROGY
3.1 Establishment of Control Points
Figure 2 showed grid sheet for setting control points. Grid sheet was drawn in 5*5 intervals by
CAD software.
Figure 3 showed 25 control points was arranged on the grid sheet, and 25 numbers wereassigned. The 13th target which is center of 25 control points is used as validation point. X Ycoordinates of control points are measured from position of grid. These heights were measured
with steel ruler. Table 1 showed ground coordinates of control points.

Figure 2: Grid Sheet for Setting Control Points

Figure 3: Arranged 25 Control Points on Grid Sheet

Table 1: Ground Coordinate of 25 Control Points
Target X(mm) Y(mm) Z(mm) Target X(mm) Y(mm) Z(mm)10840
50 14630420962210840
41 15840
420
863420840
94 160210
354630840
111 17210
210
885840840
18 18420210
4160630
41 19630
210
577210630
126 20840
210
578420630
72 2100959630
630
41 2221001810840630
143 23420079110420
56 2463009412210420
18 25840079
13420420
58

3.2 How to Take Stereo Pair Photos
Figure 4 and Table 2 showed the appearance and the specification of “Minolta Dimage 7i”
which is used camera in this study.

Table 2: Specification of “Minolta Dimage 7i”

Image Size
CCD size
Focal Length
Image Resolution

2560*1920(pixel)
8.8*6.6(mm)7.254494(mm)0.0034375(mm/pixel)

Figure 4: Minolta Dimage 7i

In this study, 2 photos were taken for experiment. These photos were taken from different
angles (Figure 3). Figure 4 and 5 showed taken photos in this study.

Figure 5: Outline of How to Take Photos

Figure 4: Taken photo of Targets from Left

Figure 5: Taken photo of Targets from Right

3.3 Orientation
First, 6 control points are selected from 24 control points for camera orientation. 134,596
combinations are calculated. Camera position (X0, Y0, Z0) and camera angle (ω, φ, κ) iscalculated with collinearity equation from 6 control points. Following equation is collinearityequation.

u =−fxpv=−fypzpzp⎛ a11⎜R = ⎜ a 21
⎜a⎝ 31=−fa11 ( X − X 0 ) + a12 (Y − Y0 ) + a13 ( Z − Z 0 )a31 ( X − X 0 ) + a32 (Y − Y0 ) + a33 ( Z − Z 0 )=−f

a 21 ( X − X 0 ) + a 22 (Y − Y0 ) + a 23 ( Z − Z 0 )a31 ( X − X 0 ) + a32 (Y − Y0 ) + a33 ( Z − Z 0 )a12a 22a32a13 ⎞ ⎛ 100 ⎞⎛ cos ϕ 0 sin ϕ ⎞⎛ cos κ⎟⎜⎟⎜⎟ ⎜a32 ⎟ = ⎜ 0 cos ω − sin ω ⎟⎜ 010 ⎟⎜ sin κa33 ⎟⎠ ⎜⎝ 0 sin ω cos ω ⎟⎠⎜⎝ sin ϕ 0 cos ϕ ⎟⎠⎜⎝ 0− sin κcos κ00⎞⎟0⎟1 ⎟⎠( X , Y, Z ); Ground Coordinate of Target P( X 0 , Y0 , Z 0 ); Ground Coordinate of Camera Pointf(u , v)

; Focal Length; Photographic Coordinate of Target P on Photograph Imagea ij; Element of Rotation Matrix by (ω, φ, κ)Figure 6 showed outline of collinearity equation.

Figure 6: outline of collinearity equation

3.4 Evaluation Method of Error
When the orientation is finished, (X0, Y0, Z0) and (ω, φ, κ) can be calculated. For evaluating theorientation, validation point which is the 13th target was used. When the ground coordinate ofvalidation point are input to collinearlity equation, photographic coordinate (u, v) can becalculated. Then, error can be measured between calculated photographic coordinate and real
photographic coordinate. The real photo graphic coordinate was pointed out by visualinterpretation.
The orientation result in each combination pattern of control point can be evaluated by theerror calculation.

4. RESULT
In table 3, good results in each combination pattern were listed. Figure 7 showed image ofcombination pattern of control point. There are no trend in the results.

Table 3: 10 Combination Pattern When Small Error
Combination Pattern
①②
③
④
⑤
⑥
⑦
⑧
⑨
⑩

2
2
1
1
3
4
4
5
1
1

3
3
2
2
58
7
7
4
2

47
4
3
91015
125352358101218
21
65824
8
912
17
1924
8
6

1025
111123192025
1111

Photographic Cooridnate Error
Left Camera Right Camera
Average ofLeft Camera
Right Camera
Error Distance Error Distance Error Distance
X(mm)
Y(mm)
X(pixel)Y(pixel)(pixel)(pixel)(pixel)0.0684-0.1577-0.0771-0.04480.17190.08920.13050.46840.2231-0.0148-0.16810.51880.16880.34380.21910.1391-0.4279
0.16120.25950.45730.3584-0.0439-0.1722-0.4591-0.30280.17770.54990.3638-0.2662-0.0655
0.46980.06520.27410.47430.37420.15740.1452-0.2060-0.5292
0.21410.56780.39100.0335-0.04070.70600.22250.05270.74030.3965-0.56150.1268-0.28130.00790.5756
0.28140.42850.00520.79040.03810.05990.79040.07100.43070.04740.43140.4090-0.23510.43400.47170.4529Figure 7: Arrangement Pattern at Good Result

5. CONCLUSIONSIn this study, designing control frame was tried. 134,594 combination of control point werecalculated. However, critical combination pattern was not found. This time one stereo pairphotograph and one distribution of 24 control points were used. Systematic analysis will be
required to find optimum special distribution of control point.

6. REFERENCES
Jong Hyeok JEONG and Masataka TAKAGI, Bridge Monitoring System Using Close Range
Digital Photogrammetry and Web GIS, Proceeding of the 27th Asian Conference on RemoteSensing, Ulaanbaatar MONGOLIA, 2006
Jong Hyeok JEONG, Crack Monitoring Using a Digital Camera and in Image Total Station,
Proceeding of the International Symposium on Social Management Systems, 2007
Shunji MURAI (1983) “Kaiseki Shasin Sokuryo” [Analytical Photogrammetry], Japan Societyof Photogrammetry and Remote Sensing, pp.46-56
KONICA MINOLTA HOLDINGS, INC., “MINOLTA Dimage 7i User’s Manual”