This paper discusses an efficient implementation of Deterministic Ray Tracing model for indoor wi... more This paper discusses an efficient implementation of Deterministic Ray Tracing model for indoor wireless propagation. It is important to characterize the indoor propagation channel to ensure satisfactory performance of a wireless communication system. Ray tracing method is extremely effective in indoor environments for estimating the average propagation loss caused by severe multi path reflections. In this model the dominant rays are calculated using Geometrical Optics implemented by the method of images. Deterministic models are computationally expensive but provide accurate results, which become essential in Indoor Wireless site-specific propagation modeling. A Software package has been developed which performs 3-D ray tracing and calculates signal strength variations in a given wireless environment. To validate software results, experimentation at 836 MHz & 1 GHz was carried out in the building of Electrical Engineering Department at UET Lahore. Measured results were mostly found ...
Deformation monitoring with total stations, while superior in accuracy, suffers from the poor spa... more Deformation monitoring with total stations, while superior in accuracy, suffers from the poor spatial resolution obtainable by this measurement method within the limited time on a tunnel construction site, and deformation can only be detected at previously marked target points. Due to its high speed in obtaining unstructured point clouds from all surfaces within the field of view terrestrial laser scanning can be – at least – complementary in monitoring deformation. In this study we test one of the new panoramic high precision laser scanners (Leica HDS3000) for its feasibility in tunnel deformation monitoring. Accuracy is tested in a tunnel with respect to range and angle of incidence. Not all points measured by the laser scanner can serve for deformation monitoring due to measurement artifacts at edges. We propose to use segmentation for selecting the suitable points only. 1
Both airborne and terrestrial laser scanners are used to capture large point clouds of the object... more Both airborne and terrestrial laser scanners are used to capture large point clouds of the objects under study. Although for some applications, direct measurements in the point clouds may already suffice, most applications require an automatic processing of the point clouds to extract information on the shape of the recorded objects. This processing often involves the recognition of specific geometric shapes or more general smooth surfaces. This paper reviews several techniques that can be used to recognise such structures in point clouds. Applications in industry, urban planning, water management and forestry document the usefulness of these techniques. 1 This paper was written while the first author was with the Delft University of Technology.
For automatic processing of point clouds their segmentation is one of the most important processe... more For automatic processing of point clouds their segmentation is one of the most important processes. The methods based on curvature and other higher level derivatives often lead to over segmentation, which later needs a lot of manual editing. We present a method for segmentation of point clouds using smoothness constraint, which finds smoothly connected areas in point clouds. It uses only local surface normals and point connectivity which can be enforced using either k-nearest or fixed distance neighbours. The presented method requires a small number of intuitive parameters, which provide a tradeoff between underand over-segmentation. The application of the presented algorithm on industrial point clouds shows its effectiveness compared to curvature based approaches.
Deformation monitoring with total stations, while superior in accuracy, suffers from the poor spa... more Deformation monitoring with total stations, while superior in accuracy, suffers from the poor spatial resolution obtainable by this measurement method within the limited time on a tunnel construction site, and deformation can only be detected at previously marked target points. Due to its high speed in obtaining unstructured point clouds from all surfaces within the field of view terrestrial laser scanning can be ‐ at least ‐ complementary in monitoring deformation. In this study we test one of the new panoramic high precision laser scanners (Leica HDS3000) for its feasibility in tunnel deformation monitoring. Accuracy is tested in a tunnel with respect to range and angle of incidence. Not all points measured by the laser scanner can serve for deformation monitoring due to measurement artifacts at edges. We propose to use segmentation for selecting the suitable points only.
For automatic processing of point clouds their segmentation is one of the most important processe... more For automatic processing of point clouds their segmentation is one of the most important processes. The methods based on curvature and other higher level derivatives often lead to over segmentation, which later needs a lot of manual editing. We present a method for segmentation of point clouds using smoothness constraint, which finds smoothly connected areas in point clouds. It uses only local surface normals and point connectivity which can be enforced using either k-nearest or fixed distance neighbours. The presented method requires a small number of intuitive parameters, which provide a tradeoff between underand over-segmentation. The application of the presented algorithm on industrial point clouds shows its effectiveness compared to curvature based approaches.
... installaties uit puntenwolken en beelden Tahir Rabbani Shah ... I owe special thanks to all o... more ... installaties uit puntenwolken en beelden Tahir Rabbani Shah ... I owe special thanks to all of my friends from the group of SSAHolland. In this regard Shabir Dar, Naveed, Khurrum Bokhari, Zeeshan, Haroon Awais, Nafees Khan, Shailaja and Raji deserve special mention. ...
Isprs Journal of Photogrammetry and Remote Sensing, Feb 1, 2007
Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelli... more Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelling of industrial installations. Covering such an installation with point cloud data often requires data acquisition from multiple standpoints. Before the actual modelling can start the transformation parameters of all scans need to be determined. Two methods to register point clouds of industrial scenes with different
The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2002
This paper discusses an efficient implementation of Deterministic Ray Tracing model for indoor wi... more This paper discusses an efficient implementation of Deterministic Ray Tracing model for indoor wireless propagation. It is important to characterize the indoor propagation channel to ensure satisfactory performance d a wireless communication system. Ray tracing method is ...
ISPRS Journal of Photogrammetry and Remote Sensing, 2007
Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelli... more Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelling of industrial installations. Covering such an installation with point cloud data often requires data acquisition from multiple standpoints. Before the actual modelling can start the transformation parameters of all scans need to be determined. Two methods to register point clouds of industrial scenes with different
We present an efficient Hough transform for automatic detection of cylinders in point clouds. As ... more We present an efficient Hough transform for automatic detection of cylinders in point clouds. As cylinders are one of the most frequently used primitives for industrial design, automatic and robust methods for their detection and fitting are essential for reverse engineering from point clouds. The current methods employ automatic segmentation followed by geometric fitting, which requires a lot of manual interaction during modelling. Although Hough transform can be used for automatic detection of cylinders, the required 5D Hough space has a prohibitively high time and space complexity for most practical applications. We address this problem in this paper and present a sequential Hough transform for automatic detection of cylinders in point clouds. Our algorithm consists of two sequential steps of low dimensional Hough trans- forms. The first step, called Orientation Estimation, uses the Gaussian sphere of the input data and performs a 2D Hough Transform for finding strong hypotheses ...
... installaties uit puntenwolken en beelden Tahir Rabbani Shah ... I owe special thanks to all o... more ... installaties uit puntenwolken en beelden Tahir Rabbani Shah ... I owe special thanks to all of my friends from the group of SSAHolland. In this regard Shabir Dar, Naveed, Khurrum Bokhari, Zeeshan, Haroon Awais, Nafees Khan, Shailaja and Raji deserve special mention. ...
Both airborne and terrestrial laser scanners are used to capture large point clouds of the object... more Both airborne and terrestrial laser scanners are used to capture large point clouds of the objects under study. Although for some applications, direct measurements in the point clouds may already suffice, most applications require an automatic processing of the point clouds to extract ...
This paper discusses an efficient implementation of Deterministic Ray Tracing model for indoor wi... more This paper discusses an efficient implementation of Deterministic Ray Tracing model for indoor wireless propagation. It is important to characterize the indoor propagation channel to ensure satisfactory performance of a wireless communication system. Ray tracing method is extremely effective in indoor environments for estimating the average propagation loss caused by severe multi path reflections. In this model the dominant rays are calculated using Geometrical Optics implemented by the method of images. Deterministic models are computationally expensive but provide accurate results, which become essential in Indoor Wireless site-specific propagation modeling. A Software package has been developed which performs 3-D ray tracing and calculates signal strength variations in a given wireless environment. To validate software results, experimentation at 836 MHz & 1 GHz was carried out in the building of Electrical Engineering Department at UET Lahore. Measured results were mostly found ...
Deformation monitoring with total stations, while superior in accuracy, suffers from the poor spa... more Deformation monitoring with total stations, while superior in accuracy, suffers from the poor spatial resolution obtainable by this measurement method within the limited time on a tunnel construction site, and deformation can only be detected at previously marked target points. Due to its high speed in obtaining unstructured point clouds from all surfaces within the field of view terrestrial laser scanning can be – at least – complementary in monitoring deformation. In this study we test one of the new panoramic high precision laser scanners (Leica HDS3000) for its feasibility in tunnel deformation monitoring. Accuracy is tested in a tunnel with respect to range and angle of incidence. Not all points measured by the laser scanner can serve for deformation monitoring due to measurement artifacts at edges. We propose to use segmentation for selecting the suitable points only. 1
Both airborne and terrestrial laser scanners are used to capture large point clouds of the object... more Both airborne and terrestrial laser scanners are used to capture large point clouds of the objects under study. Although for some applications, direct measurements in the point clouds may already suffice, most applications require an automatic processing of the point clouds to extract information on the shape of the recorded objects. This processing often involves the recognition of specific geometric shapes or more general smooth surfaces. This paper reviews several techniques that can be used to recognise such structures in point clouds. Applications in industry, urban planning, water management and forestry document the usefulness of these techniques. 1 This paper was written while the first author was with the Delft University of Technology.
For automatic processing of point clouds their segmentation is one of the most important processe... more For automatic processing of point clouds their segmentation is one of the most important processes. The methods based on curvature and other higher level derivatives often lead to over segmentation, which later needs a lot of manual editing. We present a method for segmentation of point clouds using smoothness constraint, which finds smoothly connected areas in point clouds. It uses only local surface normals and point connectivity which can be enforced using either k-nearest or fixed distance neighbours. The presented method requires a small number of intuitive parameters, which provide a tradeoff between underand over-segmentation. The application of the presented algorithm on industrial point clouds shows its effectiveness compared to curvature based approaches.
Deformation monitoring with total stations, while superior in accuracy, suffers from the poor spa... more Deformation monitoring with total stations, while superior in accuracy, suffers from the poor spatial resolution obtainable by this measurement method within the limited time on a tunnel construction site, and deformation can only be detected at previously marked target points. Due to its high speed in obtaining unstructured point clouds from all surfaces within the field of view terrestrial laser scanning can be ‐ at least ‐ complementary in monitoring deformation. In this study we test one of the new panoramic high precision laser scanners (Leica HDS3000) for its feasibility in tunnel deformation monitoring. Accuracy is tested in a tunnel with respect to range and angle of incidence. Not all points measured by the laser scanner can serve for deformation monitoring due to measurement artifacts at edges. We propose to use segmentation for selecting the suitable points only.
For automatic processing of point clouds their segmentation is one of the most important processe... more For automatic processing of point clouds their segmentation is one of the most important processes. The methods based on curvature and other higher level derivatives often lead to over segmentation, which later needs a lot of manual editing. We present a method for segmentation of point clouds using smoothness constraint, which finds smoothly connected areas in point clouds. It uses only local surface normals and point connectivity which can be enforced using either k-nearest or fixed distance neighbours. The presented method requires a small number of intuitive parameters, which provide a tradeoff between underand over-segmentation. The application of the presented algorithm on industrial point clouds shows its effectiveness compared to curvature based approaches.
... installaties uit puntenwolken en beelden Tahir Rabbani Shah ... I owe special thanks to all o... more ... installaties uit puntenwolken en beelden Tahir Rabbani Shah ... I owe special thanks to all of my friends from the group of SSAHolland. In this regard Shabir Dar, Naveed, Khurrum Bokhari, Zeeshan, Haroon Awais, Nafees Khan, Shailaja and Raji deserve special mention. ...
Isprs Journal of Photogrammetry and Remote Sensing, Feb 1, 2007
Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelli... more Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelling of industrial installations. Covering such an installation with point cloud data often requires data acquisition from multiple standpoints. Before the actual modelling can start the transformation parameters of all scans need to be determined. Two methods to register point clouds of industrial scenes with different
The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2002
This paper discusses an efficient implementation of Deterministic Ray Tracing model for indoor wi... more This paper discusses an efficient implementation of Deterministic Ray Tracing model for indoor wireless propagation. It is important to characterize the indoor propagation channel to ensure satisfactory performance d a wireless communication system. Ray tracing method is ...
ISPRS Journal of Photogrammetry and Remote Sensing, 2007
Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelli... more Point cloud acquisition by using laser scanners provides an efficient way for 3D as-built modelling of industrial installations. Covering such an installation with point cloud data often requires data acquisition from multiple standpoints. Before the actual modelling can start the transformation parameters of all scans need to be determined. Two methods to register point clouds of industrial scenes with different
We present an efficient Hough transform for automatic detection of cylinders in point clouds. As ... more We present an efficient Hough transform for automatic detection of cylinders in point clouds. As cylinders are one of the most frequently used primitives for industrial design, automatic and robust methods for their detection and fitting are essential for reverse engineering from point clouds. The current methods employ automatic segmentation followed by geometric fitting, which requires a lot of manual interaction during modelling. Although Hough transform can be used for automatic detection of cylinders, the required 5D Hough space has a prohibitively high time and space complexity for most practical applications. We address this problem in this paper and present a sequential Hough transform for automatic detection of cylinders in point clouds. Our algorithm consists of two sequential steps of low dimensional Hough trans- forms. The first step, called Orientation Estimation, uses the Gaussian sphere of the input data and performs a 2D Hough Transform for finding strong hypotheses ...
... installaties uit puntenwolken en beelden Tahir Rabbani Shah ... I owe special thanks to all o... more ... installaties uit puntenwolken en beelden Tahir Rabbani Shah ... I owe special thanks to all of my friends from the group of SSAHolland. In this regard Shabir Dar, Naveed, Khurrum Bokhari, Zeeshan, Haroon Awais, Nafees Khan, Shailaja and Raji deserve special mention. ...
Both airborne and terrestrial laser scanners are used to capture large point clouds of the object... more Both airborne and terrestrial laser scanners are used to capture large point clouds of the objects under study. Although for some applications, direct measurements in the point clouds may already suffice, most applications require an automatic processing of the point clouds to extract ...
Uploads