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4. Summary
We implemented a wide range of experiments though
many stages in order to establish a non-image,
inexpensive and easy to use method of measureing
cross-sections of the ground. We were able to
grasp a good understanding of the problems that
became clear during each stage as well as certain
characteristics of the sensor which were not
previously known. The result of this is the fact
that we were able to review our opinion of the
suitability of non-prism laser-ranger as sensors
for obtaining information on ground surface
cross-sections. In other words, the points which
have been made clear as the characteristics of
the non-prism (prism not required ) laser-ranger
are:
*Measurement discrepancies are not on the
distance.
*During practical application, the measurement
error of the natural object can be contained
within a range of approximately 2.5times the
catalog value. (can be used as 250mm if the
catalog value is +20mm. )
*There is no effect on measurement accuracy even
if the object being measured is a natural object.
*Identifying precision is approximately 30cm at a
measurement distance of 100m (circle with a
diameter of approximately 3.2cm or a rectangele
with an area of 5.5cm). We have therefore been
able to determine that it is suitable for use as
a “Profiler”sensor,which was the aim of this
research.
5. Problems and Future Conciderations
5-1. Probrem of the Platform
The result of a wide range of experiments induced
us to determine that the non-prism laser-ranger
is the most suitable for use as an “easy to use,
inexpensive and safe profiler" sensor, which was
the aim of this research. However, there remains
an unsolved problem with the helicopter upon
which the sensor is mounted for use as a
platform. If the sensor is set to measure the
distance between the helicopter and the ground
with a precision level of +50mm, the movement of
the helicopter itself renders the measurement
values meaningless. The fact of the matter is
that it is impossible to request a helicopter
pilot to fly with a precision level of 1m, let
alone 50mm. The most expedient way to avoid this
is to use INS or GPS system. We will design and
do it in the next.
557
5-2. Working Toward a Scanning Profile
There is currently a wide variety of non-prism
(prism not required) laser-ranger on the open
market. However, most of these have basically
been designed to measure fixed points and fixed
point quantities, which places restrictions upon
them for use in the research of a profiler in
their present form. Also,as consideration is
being given to extending this research in order
to obtain ground surface cross—sectional
information,it will be necessary to have a
per-second measurement rate (pulse rate) of
several kHz at the very minimum. The measurement
rate of the non-prism laser-ranger used in this
research was only 3.3Hz per second in the
highest-speed mode. If this was changed to a
scanner sensor which emitted continuous beams at
+20degrees,total 40degrees,each scan would need
100seconds.
At the present time (March,1996), we have a plan
to get a new and optional 2kHz laser-ranger for
the sensor in early this April,1996.We have great
expectations of putting to use it.
6. References
*Yoshiaki Takahashi and Nobuyuki,1994.Profiling
of. Earth's . Surface by Non-Imaging Method.
In:Proceedings of Applied Survey Technology,
pp-81-86.
*Yoshiaki Takahashi, Nobuyuki and et al,1993.A
Method of Earth's
Non-Imaging Method (Part-1) .In:Proceedings of
Surveying Surface by
Annual Conference.Japan Society of Photogrammetry
and Remote Sensing.pp.79-82
*Yoshiaki Takahashi, Nobuyuki and et al,1994.A
Method of Earth's
Non-Imaging Method (Part-2).In:Proceedings of
Surveying Surface by
Annual Conference.Japan Society of Photogrammetry
and Remote Sensing.pp.183-186
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996
