earthquake.
2. THE CONSTITUTION AND FUNCTIONS OF GOKUU
To be portable with as many as computers, GOKUU is
programmed on UNIX using X11R5 as a window system.
Though GOKUU has its own simple CAD program, it is
connected to AutoCAD r12 to edit graphics and link
the data to GIS. For this purpose OS is confined
to Sun Solaris 2.x but when AutoCAD is detached,
GOKUU runs on most of UNIX machines. And only 10MB
is necessary to run GOKUU stand-alone. GOKUU has
the following basic
photogrammetry.
(1)MANAGEMENT of jobs and images
(2)image coordinate measurement (stereo COMPARATOR
MODE)
(3)ORIENTATION of one model
(4)adjustment for AERIAL TRIANGULATION
(5)RECTIFICATION of a stereo pair
(6)plotting and editing of graphics (PLOTTER MODE)
functions for aerial
GOKUU does not include film scanning. COMPARATOR
MODE is only for the orientation of one model, and
not intended to measure many supplementary GCPs
for aerial triangulation.
The above (2),(4),(5) and (6) are briefly
described in the following.
(2)COMPARATOR MODE (see Fig.1) measures the image
coordinates of fiducial marks and orientation
points (GCPs and supplementary GCPs). For
sub-pixel measurement, the operator has an
alternative of either manual measurement with four
times enlarged images, or semi-automatic measure-
ment by the MLSC. The accuracy in either method is
1/3 pixel, which is detailed in section 3.
Three 300%300 pixel windows below the screen in
Fig.1 are the index windows. Small scale whole
images are used for indexing. The third window is
prepared for connection of triplet images for a
small triangulation. Above two large windows are
the stereo windows for coordinate measurement,
size of which is 400x400 pixels. For image
retrieval GOKUU uses the tiling method. Original
image portions of 1200*x1200 pixels are retrieved
in a time. To ease off heavy overhead for image
access, the data are stored in blocks of 64x64
pixels. But since this method is less convenient
to roam over a wide area, we consider seamless
roaming is necessary in the next generation.
Images are displayed with 64 gray value levels.
According to preliminary tests, display with more
than 64 levels does not show any difference in
image quality even with the best quality monitor
we can ever have, e.g., MITSUBISHI Diamondtron.
Stereo view is realized by the screen split method
with a simple mirror scope, like Leica DVP
(Nolette,1992), because of economy . The operator
148
roam the images and measure point coordinates at
mess-marks in the center of the screen. The
control of image roaming is done with a mouse and
a keyboard.
(4)AERIAL TRIANGULATION executes the bundle
adjustment with optional self-calibration. It
includes the calculation of the estimates of
ground coordinates of each supplementary GCP as
well as of conventional parameter. This function
is necessary to evaluate the strength of a
network, when high precision is required like the
ground displacement measurement.
(5)RECTIFICATION (see Fig.2) makes y-parallax
free images by eliminating the distortions due to
rotation of a camera axis. Fig.2 shows the screen
to check the residual y-parallaxes. Since this
process takes much time, it can be skipped, as
long as stereo view is possible, i.e. rotation
angles are small. For this, PLOTTER MODE provides
two modes of image control.
(6)PLOTTER MODE (see Fig.3) plots graphics on a
stereo model and edits drawn graphics. The screen
design is similar to that of COMPARATOR MODE, it
is not referred to here. GOKUU has its own simple
CAD (hereafter called 3-D CAD) for the edition of
graphics. Drawn graphics are left superimposed on
the images. The 3-D CAD is connected to AutoCAD
r12, which is shown right below in Fig.4. The two
CAD programs communicate by use of the shared
memory system and semaphore in UNIX. For identifi-
cation of graphics data. every graphics is tagged
with an ID number.
The control of image roaming is just the same as
in analytical plotters. The operator controls a
ground point P(Xe Ye, Z0); then the computer
calculates the pair of corresponding image points.
We first tried to fix the images and moved the
mess-marks, but 1t was proved to fatigue eyes in
the presence of large x-parallaxes like buildings
in an urban area. Xo» Ye are controlled by the
mouse and Ze is controlled by the key board.
3. MODIFIED LSC IN COMPARATOR MODE
3.1 Matching Precision with the LSC
The LSC (Ackermann,1984) is a matching method to
consider the linear distortion of image
coordinates. Let the left and the right image
function be L(x,y) and R(X,Y) respectively.
Between the left and right coordinates, a linear
relation is assumed,
L(x,y) *n(x,y) -R(X, 0|
2 a, “| a (1)
yl. y. |
a, a, a,
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