Pub Date : 2021-03-01DOI: 10.15292/GEODETSKI-VESTNIK.2021.01.82-93
M. Aleknavičius, A. Aleknavičius, J. Valciukiene
During the period of about 15 years, there were several attempts to regulate land tenure in Lithuania by changing the procedure of land acquisition and imposing some restrictive measures for the acquisition of agricultural land. This research aimed to determine the impact of those restrictive measures on the land market. This article represents the analytical results of the statistical data on agricultural land privatisation and market sales in respect of changes in legal acts. According to the analysis, changes in land acquisition procedure had no negative effect on land privatisation and volumes of land sales nor on land sale prices during the transitional period of limited access for foreign buyers in 2004–2014. The volatility of land sales during the transitional period can be explained by the natural market cyclicality, while the steady growth of prices indicates that the land market has not yet reached its long-run equilibrium. The new regulative provisions adopted in 2014 after the transitional period was over were intended to prevent land concentration and had a positive, yet momentary, effect on the supply of private agricultural land. A significant increase in land prices after introducing those provisions was caused by the ceased supply of state land and some other causes that were not analysed in this paper.
{"title":"Protective restrictions on the acquisition of agricultural land: the impact on the land market on the example of Lithuania","authors":"M. Aleknavičius, A. Aleknavičius, J. Valciukiene","doi":"10.15292/GEODETSKI-VESTNIK.2021.01.82-93","DOIUrl":"https://doi.org/10.15292/GEODETSKI-VESTNIK.2021.01.82-93","url":null,"abstract":"During the period of about 15 years, there were several attempts to regulate land tenure in Lithuania by changing the procedure of land acquisition and imposing some restrictive measures for the acquisition of agricultural land. This research aimed to determine the impact of those restrictive measures on the land market. This article represents the analytical results of the statistical data on agricultural land privatisation and market sales in respect of changes in legal acts. According to the analysis, changes in land acquisition procedure had no negative effect on land privatisation and volumes of land sales nor on land sale prices during the transitional period of limited access for foreign buyers in 2004–2014. The volatility of land sales during the transitional period can be explained by the natural market cyclicality, while the steady growth of prices indicates that the land market has not yet reached its long-run equilibrium. The new regulative provisions adopted in 2014 after the transitional period was over were intended to prevent land concentration and had a positive, yet momentary, effect on the supply of private agricultural land. A significant increase in land prices after introducing those provisions was caused by the ceased supply of state land and some other causes that were not analysed in this paper.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44862805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2021.02.205-218
Ales Marjetic
In this article, we discuss the procedure for computing the values of the unknowns under the condition of the minimum sum of squares of the observation residuals (least-squares method), taking into account the errors in the unknowns. Many authors have already presented the problem, especially in the field of regression analysis and computations of transformation parameters. We present an overview of the theoretical foundations of the least-squares method and extensions of this method by considering the errors in unknowns in the model matrix. The method, which can be called ‘the total least-squares method’, is presented in the paper for the case of fitting the regression line to a set of points and for the case of calculating transformation parameters for the transition between the old and the new Slovenian national coordinate systems. With the results based on relevant statistics, we confirm the suitability of the considered method for solving such tasks.
{"title":"Least-squares adjustment taking into account the errors in variables","authors":"Ales Marjetic","doi":"10.15292/geodetski-vestnik.2021.02.205-218","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2021.02.205-218","url":null,"abstract":"In this article, we discuss the procedure for computing the values of the unknowns under the condition of the minimum sum of squares of the observation residuals (least-squares method), taking into account the errors in the unknowns. Many authors have already presented the problem, especially in the field of regression analysis and computations of transformation parameters. We present an overview of the theoretical foundations of the least-squares method and extensions of this method by considering the errors in unknowns in the model matrix. The method, which can be called ‘the total least-squares method’, is presented in the paper for the case of fitting the regression line to a set of points and for the case of calculating transformation parameters for the transition between the old and the new Slovenian national coordinate systems. With the results based on relevant statistics, we confirm the suitability of the considered method for solving such tasks.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2021.02.234-259
Nina Kranjec, M. Čekada, M. Kobal
Based on the laser point clouds of 240 individual trees that were also identified in the field, we developed decision trees to distinguish deciduous and coniferous trees and individual tree species: Picea abies, Larix decidua, Pinus sylvestris, Fagus sylvatica, Acer pseudoplatanus, Fraxinus excelsior. The volume of the upper part of the tree crown (height of 3 m) and the average intensity of the laser reflections were used as explanatory variables. There were four aerial laser datasets: May 2012, September 2012, March 2013 and July 2015. We found that the combination of the volume and the average intensity of the first three laser datasets was the most reliable for predicting the selected tree species (60% model performance). A slightly poorer model performance was obtained if only the average intensity of the first three datasets was used (54% model performance). The worst model performance was given by the intensities (31 % model performance) or the volumes (21 % model performance) of dataset 4, which represents the national laser scanning of Slovenia (LSS). The best performing was the deciduous and coniferous separation, which achieved 75% and 95% success based on the test data (combination of volume and average intensity of the first three laser datasets). Using only the LSS intensities, deciduous and coniferous trees could be separated with 81% success.
{"title":"Predicting tree species based on the geometry and intensity of aerial laser scanning point cloud of treetops","authors":"Nina Kranjec, M. Čekada, M. Kobal","doi":"10.15292/geodetski-vestnik.2021.02.234-259","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2021.02.234-259","url":null,"abstract":"Based on the laser point clouds of 240 individual trees that were also identified in the field, we developed decision trees to distinguish deciduous and coniferous trees and individual tree species: Picea abies, Larix decidua, Pinus sylvestris, Fagus sylvatica, Acer pseudoplatanus, Fraxinus excelsior. The volume of the upper part of the tree crown (height of 3 m) and the average intensity of the laser reflections were used as explanatory variables. There were four aerial laser datasets: May 2012, September 2012, March 2013 and July 2015. We found that the combination of the volume and the average intensity of the first three laser datasets was the most reliable for predicting the selected tree species (60% model performance). A slightly poorer model performance was obtained if only the average intensity of the first three datasets was used (54% model performance). The worst model performance was given by the intensities (31 % model performance) or the volumes (21 % model performance) of dataset 4, which represents the national laser scanning of Slovenia (LSS). The best performing was the deciduous and coniferous separation, which achieved 75% and 95% success based on the test data (combination of volume and average intensity of the first three laser datasets). Using only the LSS intensities, deciduous and coniferous trees could be separated with 81% success.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2021.02.219-233
M. Kuhar, Robert Brglez, Božo Koler
This paper describes the quality determination of heights above mean sea level using RTK GNSS-levelling and new height reference surface SLO_VRP2016/Koper on the city area of Ljubljana. At 57 chosen benchmarks, quasigeoid heights were determined using ellipsoidal heights, determined with RTK GNNS-levelling technique and heights above mean sea level in the new height system SVS2010. The measured quasigeoid heights were compared with values interpolated from the new height reference surface SLO_VRP2016/Koper.
{"title":"Quality determination of mean sea level heights with GNSS levelling on the Ljubljana city area","authors":"M. Kuhar, Robert Brglez, Božo Koler","doi":"10.15292/geodetski-vestnik.2021.02.219-233","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2021.02.219-233","url":null,"abstract":"This paper describes the quality determination of heights above mean sea level using RTK GNSS-levelling and new height reference surface SLO_VRP2016/Koper on the city area of Ljubljana. At 57 chosen benchmarks, quasigeoid heights were determined using ellipsoidal heights, determined with RTK GNNS-levelling technique and heights above mean sea level in the new height system SVS2010. The measured quasigeoid heights were compared with values interpolated from the new height reference surface SLO_VRP2016/Koper.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2021.02.282-297
Matthews Siphiwe Mphuthi, P. Odera
The vertical offset and the geopotential value over South Africa is estimated on the four fundamental benchmarks in relation to the international height reference system (IHRS). It is estimated to obtain discrepancies between the South African local vertical datum (W_P) and the global vertical datum (W_0). A single-point-based geodetic boundary value problem (GBVP) approach was used following Molodensky theory for estimating the height anomalies from the disturbing potential (T_P) using Bruns’s formula. The gravity potential at each tide gauge benchmark (TGBM) in South Africa deviates from the potential of the global reference surface by 0.589,-1.993,-2.593 and 2.154 m2s-2 for Cape Town, Port Elizabeth, East London and Durban, respectively. The corresponding vertical datum offsets between the international height reference system and the four fundamental benchmarks over South Africa are 6.013, -20.347, -26.478, and 21.996 cm for Cape Town, Port Elizabeth, East London and Durban, respectively. These offsets can be used for the unification of the South African vertical datum at the four tide gauge benchmarks in a manner that is consistent to the international height reference system.
{"title":"Estimation of vertical datum offset for the South African vertical datum, in relation to the international height reference system","authors":"Matthews Siphiwe Mphuthi, P. Odera","doi":"10.15292/geodetski-vestnik.2021.02.282-297","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2021.02.282-297","url":null,"abstract":"The vertical offset and the geopotential value over South Africa is estimated on the four fundamental benchmarks in relation to the international height reference system (IHRS). It is estimated to obtain discrepancies between the South African local vertical datum (W_P) and the global vertical datum (W_0). A single-point-based geodetic boundary value problem (GBVP) approach was used following Molodensky theory for estimating the height anomalies from the disturbing potential (T_P) using Bruns’s formula. The gravity potential at each tide gauge benchmark (TGBM) in South Africa deviates from the potential of the global reference surface by 0.589,-1.993,-2.593 and 2.154 m2s-2 for Cape Town, Port Elizabeth, East London and Durban, respectively. The corresponding vertical datum offsets between the international height reference system and the four fundamental benchmarks over South Africa are 6.013, -20.347, -26.478, and 21.996 cm for Cape Town, Port Elizabeth, East London and Durban, respectively. These offsets can be used for the unification of the South African vertical datum at the four tide gauge benchmarks in a manner that is consistent to the international height reference system.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2021.04.533-558
Gregor Čok, S. Drobne, Gašper Mrak, Mojca Foški, Alma Zavodnik Lamovšek
The paper presents the results of a study to define the current size and location of workplaces and business entities in the area. The research was conducted in three stages. In the first step, the analysis of the size and distribution of workplaces according to the municipalities in the Republic of Slovenia for the 2007-2019 period was carried out. In the second step, the size and distribution of business entities in the space were examined. In the third step, a more detailed analysis was carried out in the test area of the Osrednjeslovenska statistical region, based on: the location in Ljubljana Urban Municipality (hereinafter referred to as MOL), in the municipalities directly bordering MOL and in the other municipalities of the Osrednjeslovenska statistical region. At this stage we also focused on the sector of activity of business entities. A strong upward trend in workplaces was found in only a few major urban centres along the motorway junction, especially in MOL. The same applies to the concentration of business entities. All this suggests that the existing practice of planning activities in physical space does not follow the strategic orientations of spatial acts, which could better control the spatial processes and their consequences.
{"title":"The impact of the centralisation of workplaces and business entities on spatial development","authors":"Gregor Čok, S. Drobne, Gašper Mrak, Mojca Foški, Alma Zavodnik Lamovšek","doi":"10.15292/geodetski-vestnik.2021.04.533-558","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2021.04.533-558","url":null,"abstract":"The paper presents the results of a study to define the current size and location of workplaces and business entities in the area. The research was conducted in three stages. In the first step, the analysis of the size and distribution of workplaces according to the municipalities in the Republic of Slovenia for the 2007-2019 period was carried out. In the second step, the size and distribution of business entities in the space were examined. In the third step, a more detailed analysis was carried out in the test area of the Osrednjeslovenska statistical region, based on: the location in Ljubljana Urban Municipality (hereinafter referred to as MOL), in the municipalities directly bordering MOL and in the other municipalities of the Osrednjeslovenska statistical region. At this stage we also focused on the sector of activity of business entities. A strong upward trend in workplaces was found in only a few major urban centres along the motorway junction, especially in MOL. The same applies to the concentration of business entities. All this suggests that the existing practice of planning activities in physical space does not follow the strategic orientations of spatial acts, which could better control the spatial processes and their consequences.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2021.02.189-204
F. Dimc, P. P. Preseren, M. Bazec
This paper presents the results of a vulnerability test of several geodetic Global Navigation Satellite System (GNSS) receivers in case of intentional signal interference in the frequency L1 for GPS (Global Positioning System). Nine instruments from different manufacturers (i.e., Leica Geosystems AG, Trimble Inc., Javad GNSS) were tested. The test was based on static and kinematic jamming. A static scenario with three-minute interruptions was followed by experiments with a stationary jammer located at distances from 10 m to 160 m from the receivers. For short-term kinematic interference, the jammer was installed in the vehicle, which passed the GNSS instruments at different speeds. An analysis of different scenarios showed that the jammer interrupted GPS but not GLONASS signals in certain situations. Since Galileo was not nominally operational at the time of the July 2019 measurements, only GPS and GLONASS were eligible for the study. The geodetic GNSS instruments reacted to the interruptions with a decreased signal-to-noise-ratio (SNR) and either with a complete inability to determine the code/phase position or with an incorrect calculation of phase ambiguities (initialization), which also affected the quality of the positioning. The proximity of the jammer played the most significant role in the complete inability to receive the signal; however, for the incorrect positioning longer duration of jamming was also a reason.
{"title":"Operation of geodetic GNSS instruments under chirp signal L1 jamming","authors":"F. Dimc, P. P. Preseren, M. Bazec","doi":"10.15292/geodetski-vestnik.2021.02.189-204","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2021.02.189-204","url":null,"abstract":"This paper presents the results of a vulnerability test of several geodetic Global Navigation Satellite System (GNSS) receivers in case of intentional signal interference in the frequency L1 for GPS (Global Positioning System). Nine instruments from different manufacturers (i.e., Leica Geosystems AG, Trimble Inc., Javad GNSS) were tested. The test was based on static and kinematic jamming. A static scenario with three-minute interruptions was followed by experiments with a stationary jammer located at distances from 10 m to 160 m from the receivers. For short-term kinematic interference, the jammer was installed in the vehicle, which passed the GNSS instruments at different speeds. An analysis of different scenarios showed that the jammer interrupted GPS but not GLONASS signals in certain situations. Since Galileo was not nominally operational at the time of the July 2019 measurements, only GPS and GLONASS were eligible for the study. The geodetic GNSS instruments reacted to the interruptions with a decreased signal-to-noise-ratio (SNR) and either with a complete inability to determine the code/phase position or with an incorrect calculation of phase ambiguities (initialization), which also affected the quality of the positioning. The proximity of the jammer played the most significant role in the complete inability to receive the signal; however, for the incorrect positioning longer duration of jamming was also a reason.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2021.04.559-593
S. Šanca, K. Oštir, Alen Mangafić
Building footprint detection based on orthophotos can be used to update the building cadastre. In recent years deep learning methods using convolutional neural networks have been increasingly used around the world. We present an example of automatic building classification using our datasets made of colour near-infrared orthophotos (NIR-R-G) and colour orthophotos (R-G-B). Building detection using pretrained weights from two large scale datasets Microsoft Common Objects in Context (MS COCO) and ImageNet was performed and tested. We applied the Mask Region Convolutional Neural Network (Mask R-CNN) to detect the building footprints. The purpose of our research is to identify the applicability of pre-trained neural networks on the data of another colour space to build a classification model without re-learning.
基于正射影像的建筑物足迹检测可用于建筑物地籍更新。近年来，使用卷积神经网络的深度学习方法在世界范围内得到了越来越多的应用。我们提出了一个使用彩色近红外正射影像(NIR-R-G)和彩色正射影像(R-G-B)组成的数据集进行自动建筑分类的例子。使用来自两个大型数据集Microsoft Common Objects in Context (MS COCO)和ImageNet的预训练权值进行建筑检测并进行了测试。我们应用掩模区域卷积神经网络(Mask R-CNN)来检测建筑物足迹。我们研究的目的是确定预训练的神经网络在另一个色彩空间数据上的适用性，以建立一个不需要重新学习的分类模型。
{"title":"Building detection with convolutional networks trained with transfer learning","authors":"S. Šanca, K. Oštir, Alen Mangafić","doi":"10.15292/geodetski-vestnik.2021.04.559-593","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2021.04.559-593","url":null,"abstract":"Building footprint detection based on orthophotos can be used to update the building cadastre. In recent years deep learning methods using convolutional neural networks have been increasingly used around the world. We present an example of automatic building classification using our datasets made of colour near-infrared orthophotos (NIR-R-G) and colour orthophotos (R-G-B). Building detection using pretrained weights from two large scale datasets Microsoft Common Objects in Context (MS COCO) and ImageNet was performed and tested. We applied the Mask Region Convolutional Neural Network (Mask R-CNN) to detect the building footprints. The purpose of our research is to identify the applicability of pre-trained neural networks on the data of another colour space to build a classification model without re-learning.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2021.04.594-613
Robert Klinc, Uroš Jotanović, K. Kregar
The use of point clouds in extracting data for building information modelling (BIM) has become common recently. Managers of older buildings are working to centralise information. Documentation about mechanical installations, plumbing, electricity, and previous interventions is often stored on scattered media, frequently still on paper. In the transformation of the material world into the digital world, the point cloud is the starting point, containing information about the material world obtained by various means such as photogrammetry, terrestrial or aerial laser scanning. Manual BIM modelling for management, maintenance and future use is a time-consuming and error-prone process. We would like to automate this process and avoid these errors. Recently, there have been developed an increasing number of stand-alone programmes and add-ons that provide automated, fast, and more accurate modelling based on point cloud data. In this paper we present an investigation into the possibilities for automating the creation of BIM models from point cloud data. The result is a semi-automated process for modelling individual BIM elements, which we have tested on specific examples of modelling individual elements (walls, pipes, and columns). We note that despite the automation of the process, a high level of user interaction is still required to produce good quality models.
{"title":"Point clouds for use in building information models (BIM)","authors":"Robert Klinc, Uroš Jotanović, K. Kregar","doi":"10.15292/geodetski-vestnik.2021.04.594-613","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2021.04.594-613","url":null,"abstract":"The use of point clouds in extracting data for building information modelling (BIM) has become common recently. Managers of older buildings are working to centralise information. Documentation about mechanical installations, plumbing, electricity, and previous interventions is often stored on scattered media, frequently still on paper. In the transformation of the material world into the digital world, the point cloud is the starting point, containing information about the material world obtained by various means such as photogrammetry, terrestrial or aerial laser scanning. Manual BIM modelling for management, maintenance and future use is a time-consuming and error-prone process. We would like to automate this process and avoid these errors. Recently, there have been developed an increasing number of stand-alone programmes and add-ons that provide automated, fast, and more accurate modelling based on point cloud data. In this paper we present an investigation into the possibilities for automating the creation of BIM models from point cloud data. The result is a semi-automated process for modelling individual BIM elements, which we have tested on specific examples of modelling individual elements (walls, pipes, and columns). We note that despite the automation of the process, a high level of user interaction is still required to produce good quality models.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.15292/geodetski-vestnik.2022.01.260-281
S. Mahmood, Z. Majid, K. M. Idris, Muhammad Hamid Chaudhry
Terrestrial laser scanners (TLS) are used for a variety of applications, e.g., surveying, forestry, cultural heritage preservation, mining, topographic mapping, urban planning, forensics etc. This technology has made a huge shift in 3D spatial data collection due to much faster speed compared to other techniques. In the absence of guiding principles for positioning TLS relative to an object, surveyors collect data at maximum arrangements of scanning geometry elements due to fear of incomplete data of TLS. In 3D spatial data acquisition, positional accuracy and Level of Detail (LOD) are major considerations and are dependent on laser incident angle, footprint size, range and resolution. Mathematical models have been developed relating range, incident angle and laser footprint size for different surface configurations. These models can be used to position TLS to collect data at required positional accuracy and LOD. Models have been verified by deriving one model from other surface models by changing parameters. Effects of incident angle and footprint size have been studied mathematically and experimentally on a natural sloping surface. From the results, surveyors can plan the positioning of the scanner so that data is collected at the required accuracy and LOD.
{"title":"Influence of incident angle and laser footprint on precision and level of detail in terrestrial laser scanner measurements","authors":"S. Mahmood, Z. Majid, K. M. Idris, Muhammad Hamid Chaudhry","doi":"10.15292/geodetski-vestnik.2022.01.260-281","DOIUrl":"https://doi.org/10.15292/geodetski-vestnik.2022.01.260-281","url":null,"abstract":"Terrestrial laser scanners (TLS) are used for a variety of applications, e.g., surveying, forestry, cultural heritage preservation, mining, topographic mapping, urban planning, forensics etc. This technology has made a huge shift in 3D spatial data collection due to much faster speed compared to other techniques. In the absence of guiding principles for positioning TLS relative to an object, surveyors collect data at maximum arrangements of scanning geometry elements due to fear of incomplete data of TLS. In 3D spatial data acquisition, positional accuracy and Level of Detail (LOD) are major considerations and are dependent on laser incident angle, footprint size, range and resolution. Mathematical models have been developed relating range, incident angle and laser footprint size for different surface configurations. These models can be used to position TLS to collect data at required positional accuracy and LOD. Models have been verified by deriving one model from other surface models by changing parameters. Effects of incident angle and footprint size have been studied mathematically and experimentally on a natural sloping surface. From the results, surveyors can plan the positioning of the scanner so that data is collected at the required accuracy and LOD.","PeriodicalId":44295,"journal":{"name":"Geodetski Vestnik","volume":null,"pages":null},"PeriodicalIF":0.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66960790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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