The international archives of the photogrammetry, remote sensing and spatial information sciences/International archives of the photogrammetry, remote sensing and spatial information sciences, Feb 14, 2024
The process of 3D building modeling serves a multitude of practical and strategic purposes across... more The process of 3D building modeling serves a multitude of practical and strategic purposes across diverse industries. Building a 3D model involves employing a range of techniques and technologies. Among these, the most used methods include 3D laser scanning and photogrammetry, whether applied at close-range or through the use of Unmanned Aerial Systems (UAS). In photogrammetry, ground control points (GCPs) are generally needed to scale and georeference the digital reconstruction process, but it is a timeconsuming practice or sometimes impractical or dangerous. This paper aims to evaluate the efficiency of two integrated devices to perform photogrammetric 3D reconstruction without GCPs. They are both composed by a Sony ZV1 camera coupled with two different RTK/PPK GNSS system: the Emlid Reach RS2 GNSS receiver and the Emlid Reach M2 module with a multi-band GNSS helical antenna. Different sets of images were acquired with the two proposed devices for the lever-arm estimation and to perform the 3D surveying of the Galata monastery historical monument. The accuracy of the process and derived dense point clouds is assessed by comparing them with GCPs and a reference point cloud derived by fusing an UAS and a high-resolution mobile laser scanning point cloud. The ultimate goal is to obtain a 3D building model without the use of GCPs in the process of bundle block adjustment with centimeter accuracy.
A new method for the accuracy evaluation of a manufactured piece
IOP conference series, Nov 3, 2015
To evaluate the accuracy of a manufactured piece, it must be measured and compared with a referen... more To evaluate the accuracy of a manufactured piece, it must be measured and compared with a reference model, namely the designed 3D model, based on geometrical elements. In this paper a new method for the precision evaluation of a manufactured piece is proposed, which implies the creation of the piece digital 3D model based on digital images and its transformation into a 3D mesh surface. The differences between the two models, the designed model and the new created one, are calculated using the Hausdorff distance. The aim of this research is to determine the differences between two 3D models, especially CAD models, with high precision, in a completely automated way. To obtain the results, a small piece has been photographed with a digital camera, that was calibrated using a 3D calibration object, a target consisting of a number of 42 points, 36 placed in the corners of 9 wood cubes with different heights and 6 of them placed at the middle of the distance between the cubes, on a board. This target was previously tested, the tests showing that using this calibration target instead of a 2D calibration grid, the precision of the final 3D model is improved with approximatly 50%. The 3D model of the manufactured piece was created using two methods. First, based on digital images, a point cloud was automatically generated and after the filtering process, the remaining points were interpolated, obtaining the piece 3D model as a mesh surface. Second, the piece 3D model was created using also the digital images, based on its characteristic points, resulting a CAD model, that was transformed into a mesh surface. Finally, the two 3D models were compared with the designed model, using the CloudCompare software, thus resulting the imperfections of the manufactured piece. The proposed method highlights the differences between the two models using a color palette, offering at the same time a global comparison.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, May 25, 2023
Unmanned Aerial Systems (UAS) are increasingly used in different applications, including 3D urban... more Unmanned Aerial Systems (UAS) are increasingly used in different applications, including 3D urban modelling, cadastral mapping, urban planning, GIS information system and other fields because of their advantages. As a consequence, UAS equipment is constantly developed to provide more accurate results in a more reliable mode. This paper aims to evaluate the performances of a low-cost UAS system, namely DJI Phantom 4 Pro v2 equipped with a TeoKIT GNSS PPK (post-processing kinematic) module for cadastral mapping purposes. Two fights (oblique and nadir) over a residential area at 60 m height were performed and some 100 ground points were used to derive RMSE accuracies. Comparison between GNSS-aided with PPK processing and indirect georeferencing processes are performed. Given a mobile laser scanner (MLS) point cloud as ground truth, comparison with UAS point clouds and manually digitized features are also performed and reported.
Instrumente de MODelare matematică a proceselor de inferfaţă Sol-Plante-Atmosferă care controlează scurgerea apei pe versant, eroziunea şi evapotranspiraţia de la scară locală la scară bazinală în funcţie de variabile NUTRIţionale şi ecoTOXicologice relevante pentru etajul ierbos şi cel arboricol
Three-Dimensional Transformation Of Coordinate Systems Using Nonlinear Analysis – Procrustes Algorithm
The coordinates transformation between two projection systems is increasingly approached in geode... more The coordinates transformation between two projection systems is increasingly approached in geodesy, photogrammetry and computer vision. This issue led to widespread development of algorithms that offer high accuracy and fast processing time. One of this algorithms was presented in this paper, namely the Procrustes algorithm, which involves the usage of seven parameters of transformation (three of translation, three of rotation and one scalar). The main advantages of this algorithm is that you don't have to know the initial values of the parameters, like in the case of iterative numerical methods and the process of equations linearization in order to obtain the equation correction system, isn't necessary. So, to the standard equation of 3D- transformation, the Lagrange function is applied, together with some constraints on rotation matrix (R must be orthogonal) and some derivation conditions. In order to obtain more accurate results in the 3D transformation of coordinates th...
For many years, close-range photogrammetry has been dealing with the extraction of high accurate ... more For many years, close-range photogrammetry has been dealing with the extraction of high accurate informations from images. The used techniques, mostly require a very precise calibration of cameras, either metric or non-metric cameras. This article presents the importance of a good determination of the intrinsic parameters in obtaining a high quality and accurate 3D model. In order to obtain the results, the 3D model of a sphere was created, using images acquired with the Canon PowerShot SX120 IS digital camera, whose intrinsic parameters were determined, using different calibration methods and objects. Finally, the 3D models obtained by using the same digital camera and different intrinsic parameters were compared with the model created with a precision of 10 µm based on the measurements made with the help of a micrometer. The differences between this models represent the influence of each calibration method on the accuracy of the final 3D model.
Environmental Engineering and Management Journal, 2016
In this paper, the steps used in the process of building 3D model creation, using images acquired... more In this paper, the steps used in the process of building 3D model creation, using images acquired with the UMK 10/1318 metric terrestrial photogrammetric camera and digital images acquired with the Canon EOS Rebel XSi/450D digital non-metric camera, are presented in detail. For the calibration process of both cameras, the Heikkila and Silven algorithm and a 3D calibration object were used. In order to save time, both on the field and back to the office, instead of taking and processing UMK images by the classic method of stereophotogrammetry, a new methodology was suggested. So, the UMK 10/1318 photogrammetric camera is used in a modern process of acquisition and processing of terrestrial images through the multi-image photogrammetric process. The buildings 3D models accuracy was evaluated based on the coordinates of the characteristic points and by a proposed method which implies the transformation of the 3D model into a 3D mesh surface. While applying this method, the 3D model is compared with a reference model created based on TLS (Terrestrial Laser Scanner) data, using as comparison metric the Hausdorff distance. The purpose of this work is to analyse the degree of confidence when using a non-metric digital camera to create a building 3D model and to determine the differences between two 3D models, especially CAD models, with high precision, in a completely automated way.
Environmental Engineering and Management Journal, 2013
The geodetic, photogrammetric and topographic works necessary for the introduction of cadastre we... more The geodetic, photogrammetric and topographic works necessary for the introduction of cadastre were performed in the city of Iasi in a series of various coordinate systems depending of the cartographic projections used in different periods of time. In a first phase (1951-1973) the creation and the organization of topographical plans relied on the coordinate system of the Local Stereographic Projection-Iasi with the central point at Golia and the Gauss-Krüger Conformal Transverse Cylindrical Projection. From 1973, the 1970 Stereographic projection on unique secant plan was adopted. The cadastral works performed between 2005 and 2009 in the territorial administrative unit of the city of Iasi were drawn up using the 1970 Stereographic projection system. For the study of specific deformations when different projection systems are used, they were first determined and then followed the comparative analysis due to the cartographic representation of a curve surface on a plane one. For this, the values of linear and areolar deformations were calculated based on the plane geographical and rectangular coordinates of the extreme points of cartographic framing for the territory of the city of Iasi.
Environmental Engineering and Management Journal, 2013
In recent years non-metric digital cameras have known a great development, being used in wide app... more In recent years non-metric digital cameras have known a great development, being used in wide applications, such as: real time monitoring and preservation of cultural heritage, the shoreline dynamics study, the wave movement for costal protection, soil erosion, etc. Clasic photogrammetry with the use of metric cameras are still of great use in areas such as architecture and environmental imaging. An old problem occurs when we want to extract metric information from our environment using closerange photogrammetry, with metric or non-metric calibrated cameras. There are many methods for this process that have been developed in some studies, by several authors. In this paper we present the Heikkilä and Silven method to determine the parameters of the UMK 10/1318 terrestrial photogrammetric camera and the parameters of a Canon EOS Rebel XSi/450D digital camera. To achive the proposed goal, a 3D calibration object was made on which, 42 points with known 3D coordinates were marked. The 3D coordinates were measured with the help of a Coordinate Measuring Machine (CMM) produced by Aberlink, with a 2µm precision. Through this calibration process the standard projective parameters of effective focal length and principal point along with radial and tangential distortion coefficients were determined. The purpose of this work is to make a first step in the analysis of the degree of confidence when using a non-metric camera to reconstruct an object in 3D.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2017
Nowadays, Unmanned Aerial Systems (UASs) are a wide used technique for acquisition in order to cr... more Nowadays, Unmanned Aerial Systems (UASs) are a wide used technique for acquisition in order to create buildings 3D models, providing the acquisition of a high number of images at very high resolution or video sequences, in a very short time. Since low-cost UASs are preferred, the accuracy of a building 3D model created using this platforms must be evaluated. To achieve results, the dean's office building from the Faculty of "Hydrotechnical Engineering, Geodesy and Environmental Engineering" of Iasi, Romania, has been chosen, which is a complex shape building with the roof formed of two hyperbolic paraboloids. Seven points were placed on the ground around the building, three of them being used as GCPs, while the remaining four as Check points (CPs) for accuracy assessment. Additionally, the coordinates of 10 natural CPs representing the building characteristic points were measured with a Leica TCR 405 total station. The building 3D model was created as a point cloud which was automatically generated based on digital images acquired with the low-cost UASs, using the image matching algorithm and different software like 3DF Zephyr, Visual SfM, PhotoModeler Scanner and Drone2Map for ArcGIS. Except for the PhotoModeler Scanner software, the interior and exterior orientation parameters were determined simultaneously by solving a self-calibrating bundle adjustment. Based on the UAS point clouds, automatically generated by using the above mentioned software and GNSS data respectively, the parameters of the east side hyperbolic paraboloid were calculated using the least squares method and a statistical blunder detection. Then, in order to assess the accuracy of the building 3D model, several comparisons were made for the facades and the roof with reference data, considered with minimum errors: TLS mesh for the facades and GNSS mesh for the roof. Finally, the front facade of the building was created in 3D based on its characteristic points using the PhotoModeler Scanner software, resulting a CAD (Computer Aided Design) model. The results showed the high potential of using low-cost UASs for building 3D model creation and if the building 3D model is created based on its characteristic points the accuracy is significantly improved.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2012
The result of the terrestrial laser scanning is an impressive number of spatial points, each of t... more The result of the terrestrial laser scanning is an impressive number of spatial points, each of them being characterized as position by the X, Y and Z coordinates , by the value of the laser reflectance and their real color, expressed as RGB (Red, Green, Blue) values. The color code for each LIDAR point is taken from the georeferenced digital images, taken with a high resolution panoramic camera incorporated in the scanner system. In this article I propose a new algorithm for the semiautomatic texture generation, using the color information, the RGB values of every point that has been taken by terrestrial laser scanning technology and the 3D surfaces defining the buildings facades, generated with the Leica Cyclone software. The first step is when the operator defines the limiting value, i.e. the minimum distance between a point and the closest surface. The second step consists in calculating the distances, or the perpendiculars drawn from each point to the closest surface. In the third step we associate the points whose 3D coordinates are known, to every surface, depending on the limiting value. The fourth step consists in computing the Voronoi diagram for the points that belong to a surface. The final step brings automatic association between the RGB value of the color code and the corresponding polygon of the Voronoi diagram. The advantage of using this algorithm is that we can obtain, in a semi-automatic manner, a photorealistic 3D model of the building.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2012
This article presents (comparatively) the methodology for creating a 3D model of the urban area, ... more This article presents (comparatively) the methodology for creating a 3D model of the urban area, based on terrestrial laser scanner, traditional technologies of terrestrial photogrammetry and aerial images. We are reviewing the data sources, their preliminary processing to be brought in a common system and the software used for this purpose. The case study presents the comparative results obtained using the methods listed above. To obtain the 3D models with terrestrial laser scanner systems have been used the dates achieved with ScanStation 2. To obtain the 3D model drawn by traditional photogrammetric methods using the UMK terrestrial camera, have been used auxiliary dates from topographic measurements with GPS systems and total stations as well as the current topographic plans. For the 3D model creation based on the dates taken with aerial digital cameras, were used the aerial images, taken with the ADS40 photogrammetric aerial camera. The comparative study between the three methods was accomplished by analyzing the object space representation fidelity, the precision of the 3D models obtained by comparison of the distances, areas and volumes, comparing the execution time and execution costs. The article presents the conclusions, the advantages and disadvantages of the three technologies based on the criteria listed above.
3D Point Cloud Classification of Natural Environments Using Airborne Laser Scanning Data
Airborne Laser Scanning technology has been recognized as a valuable and high precision topograph... more Airborne Laser Scanning technology has been recognized as a valuable and high precision topographic source for mapping and 3D modelling of the Earth surface. 3D point cloud classification in natural environments has become an important topic due to an increasing number of applications in geomorphology, 3D cartography, 3D modelling and environmental issues. This article presents two different three dimensional classification approaches applied for Airborne Laser Scanning point clouds. Firstly, a supervised machine learning classification algorithm using random forests, decision trees and training datasets and secondly a semi-supervized algorithm composed by a cascade of binary classifiers, based on Support Vector Machines are used for labeling each LiDAR return of the input point cloud as one of the following categories: ground, water, vegetation and gravel. The 3D classification results are demonstrated for a near natural reach of the Pielach River, the “Neubacher Au” area, located ...
Crashed Vehicle Profile Creation Based on Digital Close-Range Photogrammetry
For many years, close-range photogrammetry has been dealing with the extraction of high accuracy ... more For many years, close-range photogrammetry has been dealing with the extraction of high accuracy information from images, representing one of the most attractive and provocative researching domain. The data acquisition process is performed without any direct contact with the studied object, in a very short time, thus close-range photogrammetry has applications in areas such as: preservation of cultural heritage, soil erosion, buildings 3D modelling and vehicle measurements in damaged-based accident reconstruction. In order to determine the correct amount of the material damage caused by the traffic accident, insurance companies need accurate quantitative information regarding the damage sustained by the crashed vehicle. So, in this paper, the crashed vehicle profile was created by digital close-range photogrammetry, using the digital images acquired with a digital camera. In order to obtain the results, first the digital camera was calibrated using a 2D target, then the vehicle invo...
The international archives of the photogrammetry, remote sensing and spatial information sciences/International archives of the photogrammetry, remote sensing and spatial information sciences, Feb 14, 2024
The process of 3D building modeling serves a multitude of practical and strategic purposes across... more The process of 3D building modeling serves a multitude of practical and strategic purposes across diverse industries. Building a 3D model involves employing a range of techniques and technologies. Among these, the most used methods include 3D laser scanning and photogrammetry, whether applied at close-range or through the use of Unmanned Aerial Systems (UAS). In photogrammetry, ground control points (GCPs) are generally needed to scale and georeference the digital reconstruction process, but it is a timeconsuming practice or sometimes impractical or dangerous. This paper aims to evaluate the efficiency of two integrated devices to perform photogrammetric 3D reconstruction without GCPs. They are both composed by a Sony ZV1 camera coupled with two different RTK/PPK GNSS system: the Emlid Reach RS2 GNSS receiver and the Emlid Reach M2 module with a multi-band GNSS helical antenna. Different sets of images were acquired with the two proposed devices for the lever-arm estimation and to perform the 3D surveying of the Galata monastery historical monument. The accuracy of the process and derived dense point clouds is assessed by comparing them with GCPs and a reference point cloud derived by fusing an UAS and a high-resolution mobile laser scanning point cloud. The ultimate goal is to obtain a 3D building model without the use of GCPs in the process of bundle block adjustment with centimeter accuracy.
A new method for the accuracy evaluation of a manufactured piece
IOP conference series, Nov 3, 2015
To evaluate the accuracy of a manufactured piece, it must be measured and compared with a referen... more To evaluate the accuracy of a manufactured piece, it must be measured and compared with a reference model, namely the designed 3D model, based on geometrical elements. In this paper a new method for the precision evaluation of a manufactured piece is proposed, which implies the creation of the piece digital 3D model based on digital images and its transformation into a 3D mesh surface. The differences between the two models, the designed model and the new created one, are calculated using the Hausdorff distance. The aim of this research is to determine the differences between two 3D models, especially CAD models, with high precision, in a completely automated way. To obtain the results, a small piece has been photographed with a digital camera, that was calibrated using a 3D calibration object, a target consisting of a number of 42 points, 36 placed in the corners of 9 wood cubes with different heights and 6 of them placed at the middle of the distance between the cubes, on a board. This target was previously tested, the tests showing that using this calibration target instead of a 2D calibration grid, the precision of the final 3D model is improved with approximatly 50%. The 3D model of the manufactured piece was created using two methods. First, based on digital images, a point cloud was automatically generated and after the filtering process, the remaining points were interpolated, obtaining the piece 3D model as a mesh surface. Second, the piece 3D model was created using also the digital images, based on its characteristic points, resulting a CAD model, that was transformed into a mesh surface. Finally, the two 3D models were compared with the designed model, using the CloudCompare software, thus resulting the imperfections of the manufactured piece. The proposed method highlights the differences between the two models using a color palette, offering at the same time a global comparison.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, May 25, 2023
Unmanned Aerial Systems (UAS) are increasingly used in different applications, including 3D urban... more Unmanned Aerial Systems (UAS) are increasingly used in different applications, including 3D urban modelling, cadastral mapping, urban planning, GIS information system and other fields because of their advantages. As a consequence, UAS equipment is constantly developed to provide more accurate results in a more reliable mode. This paper aims to evaluate the performances of a low-cost UAS system, namely DJI Phantom 4 Pro v2 equipped with a TeoKIT GNSS PPK (post-processing kinematic) module for cadastral mapping purposes. Two fights (oblique and nadir) over a residential area at 60 m height were performed and some 100 ground points were used to derive RMSE accuracies. Comparison between GNSS-aided with PPK processing and indirect georeferencing processes are performed. Given a mobile laser scanner (MLS) point cloud as ground truth, comparison with UAS point clouds and manually digitized features are also performed and reported.
Instrumente de MODelare matematică a proceselor de inferfaţă Sol-Plante-Atmosferă care controlează scurgerea apei pe versant, eroziunea şi evapotranspiraţia de la scară locală la scară bazinală în funcţie de variabile NUTRIţionale şi ecoTOXicologice relevante pentru etajul ierbos şi cel arboricol
Three-Dimensional Transformation Of Coordinate Systems Using Nonlinear Analysis – Procrustes Algorithm
The coordinates transformation between two projection systems is increasingly approached in geode... more The coordinates transformation between two projection systems is increasingly approached in geodesy, photogrammetry and computer vision. This issue led to widespread development of algorithms that offer high accuracy and fast processing time. One of this algorithms was presented in this paper, namely the Procrustes algorithm, which involves the usage of seven parameters of transformation (three of translation, three of rotation and one scalar). The main advantages of this algorithm is that you don't have to know the initial values of the parameters, like in the case of iterative numerical methods and the process of equations linearization in order to obtain the equation correction system, isn't necessary. So, to the standard equation of 3D- transformation, the Lagrange function is applied, together with some constraints on rotation matrix (R must be orthogonal) and some derivation conditions. In order to obtain more accurate results in the 3D transformation of coordinates th...
For many years, close-range photogrammetry has been dealing with the extraction of high accurate ... more For many years, close-range photogrammetry has been dealing with the extraction of high accurate informations from images. The used techniques, mostly require a very precise calibration of cameras, either metric or non-metric cameras. This article presents the importance of a good determination of the intrinsic parameters in obtaining a high quality and accurate 3D model. In order to obtain the results, the 3D model of a sphere was created, using images acquired with the Canon PowerShot SX120 IS digital camera, whose intrinsic parameters were determined, using different calibration methods and objects. Finally, the 3D models obtained by using the same digital camera and different intrinsic parameters were compared with the model created with a precision of 10 µm based on the measurements made with the help of a micrometer. The differences between this models represent the influence of each calibration method on the accuracy of the final 3D model.
Environmental Engineering and Management Journal, 2016
In this paper, the steps used in the process of building 3D model creation, using images acquired... more In this paper, the steps used in the process of building 3D model creation, using images acquired with the UMK 10/1318 metric terrestrial photogrammetric camera and digital images acquired with the Canon EOS Rebel XSi/450D digital non-metric camera, are presented in detail. For the calibration process of both cameras, the Heikkila and Silven algorithm and a 3D calibration object were used. In order to save time, both on the field and back to the office, instead of taking and processing UMK images by the classic method of stereophotogrammetry, a new methodology was suggested. So, the UMK 10/1318 photogrammetric camera is used in a modern process of acquisition and processing of terrestrial images through the multi-image photogrammetric process. The buildings 3D models accuracy was evaluated based on the coordinates of the characteristic points and by a proposed method which implies the transformation of the 3D model into a 3D mesh surface. While applying this method, the 3D model is compared with a reference model created based on TLS (Terrestrial Laser Scanner) data, using as comparison metric the Hausdorff distance. The purpose of this work is to analyse the degree of confidence when using a non-metric digital camera to create a building 3D model and to determine the differences between two 3D models, especially CAD models, with high precision, in a completely automated way.
Environmental Engineering and Management Journal, 2013
The geodetic, photogrammetric and topographic works necessary for the introduction of cadastre we... more The geodetic, photogrammetric and topographic works necessary for the introduction of cadastre were performed in the city of Iasi in a series of various coordinate systems depending of the cartographic projections used in different periods of time. In a first phase (1951-1973) the creation and the organization of topographical plans relied on the coordinate system of the Local Stereographic Projection-Iasi with the central point at Golia and the Gauss-Krüger Conformal Transverse Cylindrical Projection. From 1973, the 1970 Stereographic projection on unique secant plan was adopted. The cadastral works performed between 2005 and 2009 in the territorial administrative unit of the city of Iasi were drawn up using the 1970 Stereographic projection system. For the study of specific deformations when different projection systems are used, they were first determined and then followed the comparative analysis due to the cartographic representation of a curve surface on a plane one. For this, the values of linear and areolar deformations were calculated based on the plane geographical and rectangular coordinates of the extreme points of cartographic framing for the territory of the city of Iasi.
Environmental Engineering and Management Journal, 2013
In recent years non-metric digital cameras have known a great development, being used in wide app... more In recent years non-metric digital cameras have known a great development, being used in wide applications, such as: real time monitoring and preservation of cultural heritage, the shoreline dynamics study, the wave movement for costal protection, soil erosion, etc. Clasic photogrammetry with the use of metric cameras are still of great use in areas such as architecture and environmental imaging. An old problem occurs when we want to extract metric information from our environment using closerange photogrammetry, with metric or non-metric calibrated cameras. There are many methods for this process that have been developed in some studies, by several authors. In this paper we present the Heikkilä and Silven method to determine the parameters of the UMK 10/1318 terrestrial photogrammetric camera and the parameters of a Canon EOS Rebel XSi/450D digital camera. To achive the proposed goal, a 3D calibration object was made on which, 42 points with known 3D coordinates were marked. The 3D coordinates were measured with the help of a Coordinate Measuring Machine (CMM) produced by Aberlink, with a 2µm precision. Through this calibration process the standard projective parameters of effective focal length and principal point along with radial and tangential distortion coefficients were determined. The purpose of this work is to make a first step in the analysis of the degree of confidence when using a non-metric camera to reconstruct an object in 3D.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2017
Nowadays, Unmanned Aerial Systems (UASs) are a wide used technique for acquisition in order to cr... more Nowadays, Unmanned Aerial Systems (UASs) are a wide used technique for acquisition in order to create buildings 3D models, providing the acquisition of a high number of images at very high resolution or video sequences, in a very short time. Since low-cost UASs are preferred, the accuracy of a building 3D model created using this platforms must be evaluated. To achieve results, the dean's office building from the Faculty of "Hydrotechnical Engineering, Geodesy and Environmental Engineering" of Iasi, Romania, has been chosen, which is a complex shape building with the roof formed of two hyperbolic paraboloids. Seven points were placed on the ground around the building, three of them being used as GCPs, while the remaining four as Check points (CPs) for accuracy assessment. Additionally, the coordinates of 10 natural CPs representing the building characteristic points were measured with a Leica TCR 405 total station. The building 3D model was created as a point cloud which was automatically generated based on digital images acquired with the low-cost UASs, using the image matching algorithm and different software like 3DF Zephyr, Visual SfM, PhotoModeler Scanner and Drone2Map for ArcGIS. Except for the PhotoModeler Scanner software, the interior and exterior orientation parameters were determined simultaneously by solving a self-calibrating bundle adjustment. Based on the UAS point clouds, automatically generated by using the above mentioned software and GNSS data respectively, the parameters of the east side hyperbolic paraboloid were calculated using the least squares method and a statistical blunder detection. Then, in order to assess the accuracy of the building 3D model, several comparisons were made for the facades and the roof with reference data, considered with minimum errors: TLS mesh for the facades and GNSS mesh for the roof. Finally, the front facade of the building was created in 3D based on its characteristic points using the PhotoModeler Scanner software, resulting a CAD (Computer Aided Design) model. The results showed the high potential of using low-cost UASs for building 3D model creation and if the building 3D model is created based on its characteristic points the accuracy is significantly improved.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2012
The result of the terrestrial laser scanning is an impressive number of spatial points, each of t... more The result of the terrestrial laser scanning is an impressive number of spatial points, each of them being characterized as position by the X, Y and Z coordinates , by the value of the laser reflectance and their real color, expressed as RGB (Red, Green, Blue) values. The color code for each LIDAR point is taken from the georeferenced digital images, taken with a high resolution panoramic camera incorporated in the scanner system. In this article I propose a new algorithm for the semiautomatic texture generation, using the color information, the RGB values of every point that has been taken by terrestrial laser scanning technology and the 3D surfaces defining the buildings facades, generated with the Leica Cyclone software. The first step is when the operator defines the limiting value, i.e. the minimum distance between a point and the closest surface. The second step consists in calculating the distances, or the perpendiculars drawn from each point to the closest surface. In the third step we associate the points whose 3D coordinates are known, to every surface, depending on the limiting value. The fourth step consists in computing the Voronoi diagram for the points that belong to a surface. The final step brings automatic association between the RGB value of the color code and the corresponding polygon of the Voronoi diagram. The advantage of using this algorithm is that we can obtain, in a semi-automatic manner, a photorealistic 3D model of the building.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2012
This article presents (comparatively) the methodology for creating a 3D model of the urban area, ... more This article presents (comparatively) the methodology for creating a 3D model of the urban area, based on terrestrial laser scanner, traditional technologies of terrestrial photogrammetry and aerial images. We are reviewing the data sources, their preliminary processing to be brought in a common system and the software used for this purpose. The case study presents the comparative results obtained using the methods listed above. To obtain the 3D models with terrestrial laser scanner systems have been used the dates achieved with ScanStation 2. To obtain the 3D model drawn by traditional photogrammetric methods using the UMK terrestrial camera, have been used auxiliary dates from topographic measurements with GPS systems and total stations as well as the current topographic plans. For the 3D model creation based on the dates taken with aerial digital cameras, were used the aerial images, taken with the ADS40 photogrammetric aerial camera. The comparative study between the three methods was accomplished by analyzing the object space representation fidelity, the precision of the 3D models obtained by comparison of the distances, areas and volumes, comparing the execution time and execution costs. The article presents the conclusions, the advantages and disadvantages of the three technologies based on the criteria listed above.
3D Point Cloud Classification of Natural Environments Using Airborne Laser Scanning Data
Airborne Laser Scanning technology has been recognized as a valuable and high precision topograph... more Airborne Laser Scanning technology has been recognized as a valuable and high precision topographic source for mapping and 3D modelling of the Earth surface. 3D point cloud classification in natural environments has become an important topic due to an increasing number of applications in geomorphology, 3D cartography, 3D modelling and environmental issues. This article presents two different three dimensional classification approaches applied for Airborne Laser Scanning point clouds. Firstly, a supervised machine learning classification algorithm using random forests, decision trees and training datasets and secondly a semi-supervized algorithm composed by a cascade of binary classifiers, based on Support Vector Machines are used for labeling each LiDAR return of the input point cloud as one of the following categories: ground, water, vegetation and gravel. The 3D classification results are demonstrated for a near natural reach of the Pielach River, the “Neubacher Au” area, located ...
Crashed Vehicle Profile Creation Based on Digital Close-Range Photogrammetry
For many years, close-range photogrammetry has been dealing with the extraction of high accuracy ... more For many years, close-range photogrammetry has been dealing with the extraction of high accuracy information from images, representing one of the most attractive and provocative researching domain. The data acquisition process is performed without any direct contact with the studied object, in a very short time, thus close-range photogrammetry has applications in areas such as: preservation of cultural heritage, soil erosion, buildings 3D modelling and vehicle measurements in damaged-based accident reconstruction. In order to determine the correct amount of the material damage caused by the traffic accident, insurance companies need accurate quantitative information regarding the damage sustained by the crashed vehicle. So, in this paper, the crashed vehicle profile was created by digital close-range photogrammetry, using the digital images acquired with a digital camera. In order to obtain the results, first the digital camera was calibrated using a 2D target, then the vehicle invo...
Uploads
Papers by Ersilia Oniga