24-07-2012, 02:36 PM
MOBILE MAPING SYSTEMS
[attachment=28699]
ABSTRACT
This paper describes research undertaken to develop and test a prototype system to readily capture and/or map 3D information of objects of interest in GPS-denied areas. The captured information of objects in the field is automatically determined and then sent electronically to an office environment where it interacts with GIS and CAD software. This portable mapping system combines the theory of photogrammetry, the principles of conventional land surveying and the techniques of dead-reckoning. The resulting hybrid technology has been consolidated into a device which geo-references points of interest located over any object of any size within a global or common reference system, without the need for a network of control points. The components of the single unit prototype device include: a digital compass, a medium-range laser range finder, and a GPS-enabled Smart-Phone (incorporating a digital camera and a Personal Digital Assistant with on-screen digitising facilities). The result is a portable unit that allows for automatic geo-coding of points of interests shown in the photos. In this study, the mobile unit was tested and used to determine the position of selected points located in Australian national parks (such as trees, landscape areas, public facilities and/or structures), where dense tropical rainforest vegetation and narrow valleys often obstruct GPS signals. Limitations in quality, precision and performance of the proposed system have been assessed and the architecture of the software environment is currently being improved in order to synchronize the functionalities of the proposed system and facilitate user interaction. The paper concludes with an evaluation of the system's potential for real-time operations along with the factors that present a challenge to its universal implementation today.
This study aims to develop a mobile mapping system with the integration of vehicle-based navigation data, stereo images and laser scanning data for collecting, detecting, and positioning road objects, such as road boundaries, traffic marks, road signs, traffic signal, road guide fences, electric power poles and so on. In the hand of hardware, a hybrid inertial survey system (HISS) which combined an inertial navigation system (INS), two GPS receiver, and an odometer acquires the posture data was developed. Two sets of stereo camera systems are used to collect colour images and three laser scanners are employed to acquire range data for road and roadside objects.
On the other hand, an advanced data integration technology was developed for the purpose of precise/automatic road sign extraction, traffic mark extraction, and road fence extraction and so on, by fusing collected initial navigation data, stereo images and laser range data. The major contributions of this research are high-accuracy object positioning and automatic road mapping by integration-based processing of multi-sensor data.
A lot of experiments were performed to certify and check the accuracy and efficiency of our mobile mapping technology. From achieved results of these experiments, our developed vehicle borne multi-sensor based mobile mapping system is efficient system for generating high-accuracy and high-density 3D road spatial data more rapidly and less expensively.
INRODUCTION
With the continuous development and miniaturization of mobile telecommunication systems, information can be distributed universally to end-
users anywhere and at any time (Blumer, 2004; Novak, 1995). This reality has contributed to the expansion of portable multi-sensor systems, allowing for the development of a variety of mobile mapping services based on the idea of combining or integrating in general the following functions or components:
Image capture
Coordinate measurement
Temporary data storage devices
Network connection
Screen display
On-screen digitising
Automatic orientation
A common feature of present hand-held mobile mapping systems for geo-coding points or features of interest such as government or public assets, is the use of the Global Positioning System (GPS), which has also become established as the preferred method for outdoors position sensing for wearable computers and mobile computing in general (Ladetto and Merminod, 2002).
Some of the disadvantages of portable GPS units are the loss of signals due to obstruction by tall buildings in urban environments and the attenuation of signals by foliage of tall trees in densely vegetated areas. Erroneous signals due to multi-path effects commonly caused by ‘urban canyons’ and poor accuracy in relation to the scale of the measured locations are other factors which limit the direct use of mobile GPS based units.
These drawbacks related to poor satellite ‘visibility’ and signal interference can be averted in most situations by combining the GPS receivers with other measuring devices such as laser range finders, digital compasses and imaging sensors to mention some. In this way the user may move the GPS unit away from the source of signal disruptions while still being able to remotely map objects of interest and their attributes in the challenging settings.
In this context, this paper proposes and tests a conceptual framework for a mobile mapping device which was experimentally used for geo-referencing government assets located in national parks surrounding the city of the Gold Coast in Queensland, Australia. These assets range from landscape areas, water features, utility poles to points of heritage or archaeological significance and other recreational facilities such as picnic areas and public venues. The location of these assets may be found in narrow valleys of forest areas or in reserves characterized by tall eucalyptus and coniferous trees. Figure 1 gives an indication of this type of environment.
The proposed measuring device was conceived to readily acquire and transfer 2D and relative 3D spatial and imaging information via the Internet. Its components include a GPS-enabled smart-phone with image capture capabilities and a Personal Digital Assistant (PDA) component featuring on-screen digitising facilities and an Internet connection. An external digital compass and a laser range finder are also attached to the telephone unit.
Figure 1. Densely vegetated area can attenuate GPS signals
The combination of these components allows the system to capture and geo-reference spatial information of objects of interest located in GPS denied areas to a specific control network or coordinate system. This captured information can then be used either in the field as required or sent electronically to an office environment where it can interact within GIS, visualization or CAD programs thereby assisting data validation while also improving the speed of communication.
A controlled field experiment is described to demonstrate the capabilities of the system. This experiment is not intended to be exhaustive, but it gives useful results which can be taken as typical indicators of the accuracy to be expected from the proposed measuring tool.
This was ascertained by evaluating and comparing statistically the coordinate values obtained during the test phase and the coordinates values of the same objects and their attributes as captured with what was considered to be more accurate land surveying techniques. These techniques make use of sophisticated electronic total stations combined with embedded GPS instrumentation, with all measurements linked to stable control stations situated outside the areas of poor satellite signal reception
object extraction
There are several methods related on automatic extraction and recognition, such as imagebased methods, laser-based methods, and integration methods. Image-based methods utilize colour, shape, texture etc. to recognize object. Image-based approaches have very long development history. Although well developed image-based approach has many successful applications, it has some inherent drawbacks as below :
Occlusion problem ;
Sensitive to environment conditions , such as light and shade ;
Mosaic from piece of images is costly (Figure3-a) ;
Stereo matching based 3D positioning method is difficult for realizing full automation.
Laser scanner is active sensor, so that laser-based approach is insensitive to environment conditions. Because laser scan object through point by point, exclusion problem of laser-based approach is not so serious with comparison of image-based approach. And laser scanner can acquire the continuous 3D point cloud, so there are no mosaic problem and also no stereo matching problem.
From the above analysis, it is obvious to say that laser-based approach just can solve those unsolvable problems by image-based approach. However, laser-based approach also has its inherent drawbacks such as no gray or color information so that recognition becomes difficult. BUT that is just strong point of image-based approach. The Figure 3 shows some typical merits of road object automatic extraction by integration method. (b) demonstrates that color-rendered laser point cloud is easy to extraction road data without mosaic processing ; © shows that color-rendered laser point data can be used for detecting road mark ;
COMPONENTS OF THE PROPOSED SYSTEM
illustrates the overall architecture of the proposed prototype hybrid system. The four major components include the i-mate™ JASJAM mobile phone (1) which is
GPS enabled by a wearable GPS receiver (2) (the Foretrex 100 by Garmin) via its serial cable. The positional accuracy in 2D (i.e. X and Y) of a single point determination using this receiver is reported by the manufacturer to be in the region of +/- 7 m. For applications demanding greater accuracy, the GPS unit is capable of receiving a data stream from external GPS devices or systems.
The Mobile phone is comparable in size to traditional mobile phone handsets. In addition to GSM/GPRS features, the i-mate™ JAZJAM incorporates PDA functionality using the Windows Mobile 5.0 operating system which supports Microsoft Office formats (Word, Excel, PowerPoint). This telecommunication device uses a processor operating at 400 MHz and includes 128MB of Flash RAM and 64MB SDRAM memory, which can be used to save and/or create applications and files. The i-mate™ JASJAM also incorporates a 2 MPixel CMOS (Complementary Metal Oxide Semiconductor) camera. A simplistic image processing software for Pocket PCs, namely the Spb Imageer 1.5, was downloaded as freeware from the Internet with the purpose of processing the pictures taken with the camera if required as well as to facilitate the digitisation of selected points of interest on the LCD display of the mobile phone.
[attachment=28699]
ABSTRACT
This paper describes research undertaken to develop and test a prototype system to readily capture and/or map 3D information of objects of interest in GPS-denied areas. The captured information of objects in the field is automatically determined and then sent electronically to an office environment where it interacts with GIS and CAD software. This portable mapping system combines the theory of photogrammetry, the principles of conventional land surveying and the techniques of dead-reckoning. The resulting hybrid technology has been consolidated into a device which geo-references points of interest located over any object of any size within a global or common reference system, without the need for a network of control points. The components of the single unit prototype device include: a digital compass, a medium-range laser range finder, and a GPS-enabled Smart-Phone (incorporating a digital camera and a Personal Digital Assistant with on-screen digitising facilities). The result is a portable unit that allows for automatic geo-coding of points of interests shown in the photos. In this study, the mobile unit was tested and used to determine the position of selected points located in Australian national parks (such as trees, landscape areas, public facilities and/or structures), where dense tropical rainforest vegetation and narrow valleys often obstruct GPS signals. Limitations in quality, precision and performance of the proposed system have been assessed and the architecture of the software environment is currently being improved in order to synchronize the functionalities of the proposed system and facilitate user interaction. The paper concludes with an evaluation of the system's potential for real-time operations along with the factors that present a challenge to its universal implementation today.
This study aims to develop a mobile mapping system with the integration of vehicle-based navigation data, stereo images and laser scanning data for collecting, detecting, and positioning road objects, such as road boundaries, traffic marks, road signs, traffic signal, road guide fences, electric power poles and so on. In the hand of hardware, a hybrid inertial survey system (HISS) which combined an inertial navigation system (INS), two GPS receiver, and an odometer acquires the posture data was developed. Two sets of stereo camera systems are used to collect colour images and three laser scanners are employed to acquire range data for road and roadside objects.
On the other hand, an advanced data integration technology was developed for the purpose of precise/automatic road sign extraction, traffic mark extraction, and road fence extraction and so on, by fusing collected initial navigation data, stereo images and laser range data. The major contributions of this research are high-accuracy object positioning and automatic road mapping by integration-based processing of multi-sensor data.
A lot of experiments were performed to certify and check the accuracy and efficiency of our mobile mapping technology. From achieved results of these experiments, our developed vehicle borne multi-sensor based mobile mapping system is efficient system for generating high-accuracy and high-density 3D road spatial data more rapidly and less expensively.
INRODUCTION
With the continuous development and miniaturization of mobile telecommunication systems, information can be distributed universally to end-
users anywhere and at any time (Blumer, 2004; Novak, 1995). This reality has contributed to the expansion of portable multi-sensor systems, allowing for the development of a variety of mobile mapping services based on the idea of combining or integrating in general the following functions or components:
Image capture
Coordinate measurement
Temporary data storage devices
Network connection
Screen display
On-screen digitising
Automatic orientation
A common feature of present hand-held mobile mapping systems for geo-coding points or features of interest such as government or public assets, is the use of the Global Positioning System (GPS), which has also become established as the preferred method for outdoors position sensing for wearable computers and mobile computing in general (Ladetto and Merminod, 2002).
Some of the disadvantages of portable GPS units are the loss of signals due to obstruction by tall buildings in urban environments and the attenuation of signals by foliage of tall trees in densely vegetated areas. Erroneous signals due to multi-path effects commonly caused by ‘urban canyons’ and poor accuracy in relation to the scale of the measured locations are other factors which limit the direct use of mobile GPS based units.
These drawbacks related to poor satellite ‘visibility’ and signal interference can be averted in most situations by combining the GPS receivers with other measuring devices such as laser range finders, digital compasses and imaging sensors to mention some. In this way the user may move the GPS unit away from the source of signal disruptions while still being able to remotely map objects of interest and their attributes in the challenging settings.
In this context, this paper proposes and tests a conceptual framework for a mobile mapping device which was experimentally used for geo-referencing government assets located in national parks surrounding the city of the Gold Coast in Queensland, Australia. These assets range from landscape areas, water features, utility poles to points of heritage or archaeological significance and other recreational facilities such as picnic areas and public venues. The location of these assets may be found in narrow valleys of forest areas or in reserves characterized by tall eucalyptus and coniferous trees. Figure 1 gives an indication of this type of environment.
The proposed measuring device was conceived to readily acquire and transfer 2D and relative 3D spatial and imaging information via the Internet. Its components include a GPS-enabled smart-phone with image capture capabilities and a Personal Digital Assistant (PDA) component featuring on-screen digitising facilities and an Internet connection. An external digital compass and a laser range finder are also attached to the telephone unit.
Figure 1. Densely vegetated area can attenuate GPS signals
The combination of these components allows the system to capture and geo-reference spatial information of objects of interest located in GPS denied areas to a specific control network or coordinate system. This captured information can then be used either in the field as required or sent electronically to an office environment where it can interact within GIS, visualization or CAD programs thereby assisting data validation while also improving the speed of communication.
A controlled field experiment is described to demonstrate the capabilities of the system. This experiment is not intended to be exhaustive, but it gives useful results which can be taken as typical indicators of the accuracy to be expected from the proposed measuring tool.
This was ascertained by evaluating and comparing statistically the coordinate values obtained during the test phase and the coordinates values of the same objects and their attributes as captured with what was considered to be more accurate land surveying techniques. These techniques make use of sophisticated electronic total stations combined with embedded GPS instrumentation, with all measurements linked to stable control stations situated outside the areas of poor satellite signal reception
object extraction
There are several methods related on automatic extraction and recognition, such as imagebased methods, laser-based methods, and integration methods. Image-based methods utilize colour, shape, texture etc. to recognize object. Image-based approaches have very long development history. Although well developed image-based approach has many successful applications, it has some inherent drawbacks as below :
Occlusion problem ;
Sensitive to environment conditions , such as light and shade ;
Mosaic from piece of images is costly (Figure3-a) ;
Stereo matching based 3D positioning method is difficult for realizing full automation.
Laser scanner is active sensor, so that laser-based approach is insensitive to environment conditions. Because laser scan object through point by point, exclusion problem of laser-based approach is not so serious with comparison of image-based approach. And laser scanner can acquire the continuous 3D point cloud, so there are no mosaic problem and also no stereo matching problem.
From the above analysis, it is obvious to say that laser-based approach just can solve those unsolvable problems by image-based approach. However, laser-based approach also has its inherent drawbacks such as no gray or color information so that recognition becomes difficult. BUT that is just strong point of image-based approach. The Figure 3 shows some typical merits of road object automatic extraction by integration method. (b) demonstrates that color-rendered laser point cloud is easy to extraction road data without mosaic processing ; © shows that color-rendered laser point data can be used for detecting road mark ;
COMPONENTS OF THE PROPOSED SYSTEM
illustrates the overall architecture of the proposed prototype hybrid system. The four major components include the i-mate™ JASJAM mobile phone (1) which is
GPS enabled by a wearable GPS receiver (2) (the Foretrex 100 by Garmin) via its serial cable. The positional accuracy in 2D (i.e. X and Y) of a single point determination using this receiver is reported by the manufacturer to be in the region of +/- 7 m. For applications demanding greater accuracy, the GPS unit is capable of receiving a data stream from external GPS devices or systems.
The Mobile phone is comparable in size to traditional mobile phone handsets. In addition to GSM/GPRS features, the i-mate™ JAZJAM incorporates PDA functionality using the Windows Mobile 5.0 operating system which supports Microsoft Office formats (Word, Excel, PowerPoint). This telecommunication device uses a processor operating at 400 MHz and includes 128MB of Flash RAM and 64MB SDRAM memory, which can be used to save and/or create applications and files. The i-mate™ JASJAM also incorporates a 2 MPixel CMOS (Complementary Metal Oxide Semiconductor) camera. A simplistic image processing software for Pocket PCs, namely the Spb Imageer 1.5, was downloaded as freeware from the Internet with the purpose of processing the pictures taken with the camera if required as well as to facilitate the digitisation of selected points of interest on the LCD display of the mobile phone.