2.2.2. Software
Measuring processing flow of the stereo image
workstation is shown below:
Optical Disk
Operation
Inner
Orientation
Camera >»
Calibration No
i Single Model
Bundle
Ad justment Yes
Pe Ty 1
Relative ı
Orientation ı IMS Orientation
! Obtaining Relative !
! and ;
Absolute offsotute
Orientation rientation
Parameter
i |
a aie 1
3D Measurement
(Manual /DTM)
i
3D Data Output
(DXF)
Fig.5 Flow of the Stereo Image Workstation
The orientation program consists of inner,
relative and absolute orientation, camera
calibration, bundle adjustment and IMS
orientation (which we called and includes
orientation of single photograph) conducted in
this experiment.
A measurement processing unit is a single model
in this system. Operator instructs a
measurement point by observing the stereoscopic
image on the 3D display. There are two
measurement modes; one is manual measurement
that measures interactively and the other is DTM
measurement that allocates grid points of equal
intervals in measuring area and conducts stereo
matching with batch processing by a computer.
For measuring, by using the sampled image of
whole photograph produced by the image scanner,
read 3D display images on the right and the left
in order from the optical disks. Then, display
images stereoscopically after rectifying each
image and measure the model coordinates with the
mouse moving the floating marks. Images on the
right and the left, therefore, have no y-
parallax and the floating marks are to be always
moving along the epipolar line. By using this
way, the depth can be measured by simple
operation, just coinciding the floating marks
with a measuring point on the model.
The image correlation processing is absolute
difference method and the combination of edge
extraction by a laplacian operator of the images
on the right and the left. Window size is 15 x
15 pixels, search size is approximately 90
pixels and a parameter oan be changed according
to a measuring object. Processing speed less
than 0.5 seconds and can be processed in the
interrupt mode according to the moving speed of
the floating mark. Furthermore, this processing
is used in the DTM measurement and its procedure
is omitted but the semi-automated search
processing for the corresponding point can be
conducted.
Measuring commannds have functions of line,
polyline, circle, arc, contour and Layer
(management for drawing information). The 3D
data after the measurement is processed as
stereoscopic drawing data and superimposed in
color on the stereoscopic images. Editing
commands have functions of deletion, insertion,
copy, move, conjunction, orthogonal conjunction
and so on. By using these commands, while
observing the stereoscopic data after measuring,
correction and editing can be carried out.
The obtained 3D data are output in DXF file
format. The DXF file interchanges the AutoCAD
drawing data, supported by many CADs like IGES
file format and can be applied to various kinds
of application softwares because of the spread
of the AutoCAD and simplification of operation
for drawing information.
3. ORIENTATION EXPERIMENT USING IMS
3.1. IMS System MS-100
The IMS used in this experiment is TOPCON MS-100
and consists of two digital transits (1") &
subtence bar (Measuring staff made of carbon
fiber: Length 1.2m), personal computer and
tripod with high accuracy.
To measure by this method, firstly set up two
transits at proper positions and then the
subtence bar at a position where enables precise
aiming from each transits. After collimating 3
globe shaped measuring points on the both edges
and the center of the subtence bar, transmit the
obtained data (horizontal and vertical angles)
to the computer via RS-232C and determine the
positions for the transits with network analysis
software by resection method.
The coordinate system of IMS is originated from
the position of the transit on the left hand
side and takes a base line between left and
right hands on X axis, depth on Y axis and
perpendicular direction on Z axis.
Specifications of IMS MS-100
€ Measuring accuracy : {Less than 0.3mm
(Measuring distance: 10m)
® Measuring time :30 sec./point approx.
e Memory capacity
for coordinates : 2,000 points approx.
e Connecting transits: 1-3 units
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