Abstract
Many archeological sites are being excavated every year in Japan, and abundant relics recovered from these sites have to be drawn by archeologists for archival records taking a great deal of time, labor and skill.
For saving labor and time, automatic drawing and modeling system for relics was developed by the authors. However, these systems can't films the inside-image of relics.
For a solution of the inside measurement, a small CCD camera was added to the measurement system using turntable. This CCD camera sets around the turn center of turntable and another CCD camera sets in front of the relic. These CCD cameras continue film the inside of relic till the turntable does the 1 circumference. After the film, the system can get the inside and an outside 3 D shape at same time.
1. Introduction
Large quantities of remains are discovered currently in all parts of Japan. Relics excavated from these remains are enormous number (In 1996, Excavated number is over 10,000.). In Japan, all relics need to record. A record is left unfinished with ortho-projection images and edged images. Shortening of investigation period is pursued in this record work from enormous labor being spent.
In these days, there is a demand to want to leave 3D shape record of relics with technical development of CG technology at same time. For these demands and in order to reduce work of human power, we investigated ortho-projection and drawing system and the pattern extraction technology that used CCD cameras from 1994. In the ortho-projection system, shape data of relics lacked partially. The part which illumination does not hit is a cause (occlusion). We developed a measurement system to film using a turntable and source of light from two directions (3D measurement system using line laser-beams). Fig.1 shows measurement result of the turntable system that developed for occlusion problem in ortho projection system. But this system measure only outside three-dimension shape.
Fig 1. 3D Image of outside
We examined the measurement method of simultaneous data acquisition for outside and inside of the relics.
2. Measurement System
Figure2 shows the developed measurement system and Table 1 shows experiment components.
Fig 2. Measurement System
| CCD Camera |
For out side: XC-75 (SONY)
CCD: 768pixel(w)*494pixel(h)
For in side: WAT-660D (WATEC)
CCD: 510pixel(w)*492pixel(h) |
| Line Laser |
SMF-501L-670 (M)-10-30 (MORITEX
Wave Length: 670nm |
| Turntable (Motor) |
UDX-5114 (ORIENTAL MOTOR)
Minimum angle of rotation: 0.36deg |
| PC |
CPU: Pentium 133MHz, Memory: 64MB |
| Image Processing Board |
MTAT-CL (Micro Technica) (Use ISA BUS),
Image: 512dot*512dot |
Table 1 Experiment Components
This measurement system consists of turn table and line lasers, CCD cameras, PC for image processing. CCD cameras film the target lighted up in being linear with line lasers. Each CCD camera films outside image and inside image at same time. CCD cameras continue film till the turntable does the 1 circumference.
The system grasps three dimensions of outside and inside shape target using line-images and angles of rotation degree of these times.
Figure 3 shows position relation of line lasers and CCD camera. Line lasers for outside are installed so that respect of light intersects at the center of the turntable. As for the respects of these lasers, right and left course each includes 45 deg. of leaning for the line that connected the turn center with CCD camera. This situation of the line lasers for outside is made for the target with complicated form. If a line laser illuminates the target from a direction, the omission of images may happen from shape of target. In this method, the CCD camera for out side can film line images lighting up the target from positions named objection simultaneously. As the result, this system can get three-dimension shape without lack of data that caused by occlusion.
Fig 3. Position Relation of Line Lasers and CCD cameraa
A line laser for inside is installed so that respect of light surface lights up the center of turntable and CCD camera for outside. At this system, the line laser for inside lights up the target on turntable from the table upper part and lights up inside of the target by a mirror.
In this investigation, line lasers for outside light up the part that a line laser did not light up with traditional method (1 course type) by lighting it up from 2 directions and line laser for inside lights up inside of the target. CCD camera of the front films two lines appearing on the relic surface lighted up with line lasers and CCD camera of the inside films a line appearing on the relic surface of inside lighted up with line laser at same time.
This system demand distance from the turn center, height from table base, color information (brightness) of each point about part of relics represented with lines. As a result, simultaneous data acquisition for outside and inside of the relics using multi-sensor and adding angle of rotation degree of turntable become possible. Explains the details of measurement method at later.
