The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5. Beijing 2008
2. SYSTEM’S ELEMENTS
The system consists of two parts. Each part works individually
but an interface connects them. The first part consists of camera,
image processing and analysis, section of data evaluation and
providing strategy, and dispatch centre. Camera has stationary
position and is set up without geometric restraint (Figure 2).
Image processing and analysis is integrated due to detect and
extract Geospatial data from images. The data evaluation and
providing strategy section assesses received data regarding to a
defined strategy and finalizes a strategy of processing to be
carried out by the second part of this system. The dispatch
centre, indeed, transfers the strategy to the second part of the
system.
The second part, which is a dynamic platform, includes of
vision, a computer so called Brain, and mechanical part. The
vision is supplied for navigation, the brain is the centre of
assessing and implementation of received information from the
first part, and mechanical part is the motion compartment of the
second part of the system. Next chapter will explain more about
the system in details.
3. METHODOLOGY
Figure 1 is presenting a flow chart of the whole process of the
system.
The core of the system mostly had emphasised on simplicity,
robustness, and precision. The majority of similar systems are
dependent to GPS and INS. However, GPS and INS are well
known systems for navigation, but still there are a number of
limitations for utilising of these systems. For example, there is
limitation to use the GPS in indoor sites or even in outdoor sites
under some circumstances, or INS includes some errors (Chiang
et al 2004).
The navigation system is developed based on a geography and
geometry presentation of a terrain. Two groups of stationary and
non-stationary visions were utilised here. The stationary vision
were utilised to monitoring constantly the whole of terrain in
order to detect any unknown object. In addition, the stationary
cameras are using to help navigation as well. As it was
mentioned earlier, there is no requirement for camera
calibration. Instead, A map of terrain and GIS of terrain were
initially provided and stored in a defined memory. The aspect of
implementation of a map and GIS of the terrain is that the
acquired images can be replicated on the map in order to extract
location of object according to the map. In addition, there is one
more significant advantage of utilising a map and GIS of the
terrain, which are distinguished this method. By utilising a map
and GIS of terrain stationary cameras can be set up in any
location without restraint. It means that the cameras can be set
up in an unconventional way, like upside-down, very
convergence, or upright position according to the terrain.
The non-stationary cameras are mounted on the dynamic
platform, which in this study was a RC model car. These set of
cameras are constantly acquiring images in order to search a
particular targets, which are supplied and set up in a certain
locations at the terrain. The purpose of the targets is to assist the
navigation of the second part of the system.
All acquired images from cameras are converged in a computer
was strengthen with pre-processing and post-processing
softwares, which were specifically developed for this purpose.
The softwares are required to analyse the acquired images and
implement the following steps:
1. To recognising and positioning any unknown object
in the terrain.
2. To defining the best route between the dynamic
platform and unknown object.
3. Dispatching the dynamic platform towards the
unknown object.
4. Analysing the acquired images, from camera was
mounted on the dynamic platform, for positioning
and navigation.
5. And, to updating the GIS database.
The stationary vision has been set up in different locations.
Acquired images from the stationary vision are transfer to the
image processing section. At the image processing section, the
images are analysed and interpreted in order to define an object.
The method of object tracking, which was used by Homainejad
(2007), has been adopted and implemented in this project. Once
an unknown object has been detected, the acquired images are
compiled on an existing map of the terrain due to define the
location of the object according to the map. Then the extracted
data are transferred to the next section for analysing and
providing a strategy. The adopted strategy will be transferred to
second part of the system. In this part, once the computer
component or Brain receives the information from the first part
of the system, will send a proper order to the mechanical part or
the dynamic platform. The dynamic platform, which is the
motion part of the second part of the system, moves towards the
location according to the strategy. While the second part is
moving, the vision component will acquire images in order to
search supplied targes on the terrain. The targes are supplied on
the terrain in order to facilitate the navigation processing. Once
a targe has been recognised, the image-processing component
will define the distance of the second part to the targe. The next
motion of the second part is based on the distance of the second
part to the target. If the second part is in a defined a distance
from the target, the second part will be pursue according to the
defined strategy.
4. ASSESSMENT OF THE SYSTEM AND CONCLUSION
Two groups of tests have been conducted. At the first group, all
tests have been carried out with a stationary camera. The
camera has been set up at several locations. Each time, the
camera has had different situation, but camera has to be able to
monitor whole part of the terrain. Once camera has had
convergence position with the terrain, next time camera has had
an upright position with the terrain, or camera has been set up
in upside-down position. In each situation a number of tests has
been conducted. In each test, the system has to recognise an
unknown object at the terrain and dispatches the dynamic
platform to the object. Each time, the system successfully
recognised the unknown object at the correct location and
dispatches the dynamic platform to the object and there was no
a single failing. This group of tests proves the applicability and
ability of the system while employed a GIS and a map of the
terrain.
The second group of tests has been fulfilled in order to assess
the ability of the system with stationary and non-stationary
cameras. Similar the first group tests, the stationary vision
recognised the unknown object and locates it. Then a strategy
has been adopted. The strategy has been transferred to the
second part of the system. Once the brain received the strategy.