Contribution à la segmentation et à la modélisation 3D du milieu urbain à partir de nuages de poi... more Contribution à la segmentation et à la modélisation 3D du milieu urbain à partir de nuages de points Soutenue le 1 er décembre 2020
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2020
The lack of benchmarking data for the semantic segmentation of digital heritage scenarios is hamp... more The lack of benchmarking data for the semantic segmentation of digital heritage scenarios is hampering the development of automatic classification solutions in this field. Heritage 3D data feature complex structures and uncommon classes that prevent the simple deployment of available methods developed in other fields and for other types of data. The semantic classification of heritage 3D data would support the community in better understanding and analysing digital twins, facilitate restoration and conservation work, etc. In this paper, we present the first benchmark with millions of manually labelled 3D points belonging to heritage scenarios, realised to facilitate the development, training, testing and evaluation of machine and deep learning methods and algorithms in the heritage field. The proposed benchmark, available at http://archdataset.polito.it/, comprises datasets and classification results for better comparisons and insights into the strengths and weaknesses of different machine and deep learning approaches for heritage point cloud semantic segmentation, in addition to promoting a form of crowdsourcing to enrich the already annotated database.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2015
On the occasion of the millennium celebration of Strasbourg Cathedral, a transdisciplinary resear... more On the occasion of the millennium celebration of Strasbourg Cathedral, a transdisciplinary research group composed of archaeologists, surveyors, architects, art historians and a stonemason revised the 1966-1972 excavations under the St. Lawrence’s Chapel of the Cathedral having remains of Roman and medieval masonry. The 3D modeling of the Chapel has been realized based on the combination of conventional surveying techniques for the network creation, laser scanning for the model creation and photogrammetric techniques for the texturing of a few parts. According to the requirements and the end-user of the model, the level of detail and level of accuracy have been adapted and assessed for every floor. The basement has been acquired and modeled with more details and a higher accuracy than the other parts. Thanks to this modeling work, archaeologists can confront their assumptions to those of other disciplines by simulating constructions of other worship edifices on the massive stones co...
et mots clés Depuis plus d'une dizaine d'années, des mesures de vitesses d'écoulement sont effect... more et mots clés Depuis plus d'une dizaine d'années, des mesures de vitesses d'écoulement sont effectuées sur le glacier d'Argentière. En complétant avec des mesures plus ponctuelles réalisées lors des expériences MEGATOR, nous avons pu déterminer une vitesse de référence en un point de la zone d'accumulation. La connaissance de cette vitesse d'écoulement permet alors de lever l'ambiguïté de champs de déplacement calculés à partir de couples d'images radar à synthèse d'ouverture (RSO) interférométriques acquis par les satellites ERS-1/2. Ces interférogrammes permettent de déterminer des vitesses d'écoulement sur l'ensemble du glacier, qui elles-mêmes peuvent finalement être comparées à des mesures géodésiques in-situ. Les résultats étant très proches, la méthode est ainsi validée.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2021
The detection of openings based on point clouds is generally based on geometric features namely t... more The detection of openings based on point clouds is generally based on geometric features namely the X, Y and Z coordinates of points. Existing methods exploit geometric features but ignore most of the time other attributes as colour and intensity. Such information may be however particularly interesting to recognise and segment openings in facades. In this paper, the use of radiometric information, namely colour and intensity, is investigated for the segmentation of windows from façade point clouds. The assumption is made that windows are significantly different in terms of materials and colours to be distinguished from facade walls. The exploitation of colour and intensity are considered separately. A histogram analysis method is proposed for the exploitation of intensity information whereas a region growing method based on colorimetric distances is considered for the exploitation of colours. In order to refine the results, geometric information, and more precisely depth of points with regards to façade walls, are combined to radiometric information. Several combinations of attributes are considered and provide promising results for windows segmentation based on point clouds.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2020
With their high recording rate of hundreds of thousands of points acquired per second, speed of e... more With their high recording rate of hundreds of thousands of points acquired per second, speed of execution and a remote acquisition mode, SLAM based mobile mapping systems (MMS) are a very powerful solution for capturing 3D point clouds in real time, simply by walking in the area of interest. Regarding indoor surveys, these MMS have been integrated in handheld or backpack solutions and become fast scanning sensors. Despite their advantages, the geometric accuracy of 3D point clouds guaranteed with these sensors is lower than the one reachable with static TLS. In this paper the effectiveness of two recent mobile mapping systems namely the GeoSLAM ZEB-REVO RT and the more recent GreenValley LiBackPack C50 is investigated for indoor surveys. In order to perform a reliable assessment study, several datasets produced with each sensor are compared to the high-cost georeferenced point cloud obtained with static laser scanning target-based technique.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2019
In the context of building renovation, infrared (IR) cameras are widely used to perform the energ... more In the context of building renovation, infrared (IR) cameras are widely used to perform the energy audit of buildings. They allow analysing precisely the energetic performances of existing buildings and thermal analyses represent a key step for the reduction of energy consumption. They are also used to assess the thermal comfort of people living or working in a building. Building Information Models (BIM) are widespread to plan the rehabilitation of existing buildings and laser scanning is now commonly used to capture the geometry of buildings for as-built BIM creation. The combination of thermographic and geometric data presents a high number and variety of applications (Lagüela and Díaz-Vilariño, 2016). However, geometric and thermal information are generally acquired separately by different building stakeholders and thermal analyses are performed with independence of geometry. In this paper, the combination of thermal and geometric information is investigated for indoor of buildings. The aim of the project is to create 3D thermographic point clouds based on data acquired by a laser scanner and a thermal camera. Based on these point clouds, BIM models might be enriched with thermal information through the scan-to-BIM process.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2017
The use of Terrestrial Laser Scanner (TLS) tends to become a solution in many research areas rela... more The use of Terrestrial Laser Scanner (TLS) tends to become a solution in many research areas related to large scale surveying. Meanwhile, the technological advances combined with the investigation of user needs have brought to the design of innovative devices known as scanning total stations. Such instruments merge in a unique hardware both scanning and surveying facilities. Even if their scanning rate is often reduced compared to conventional TLS, they make it possible to directly georeference laser scanning projects and to complete them with measurements of individual points of interest. The recent Trimble SX10 which was launched on the market in early October 2016 has been tested and some experiences carried out with it are reported in this paper. The analyses mainly focus on the survey of a building facade. Next to laser scanning survey, a photogrammetry campaign using an Unmanned Aerial Vehicle (UAV) has been carried out. These different datasets are used to assess the Trimble SX10 issued point clouds through a set of comparisons. Since georeferencing is possible either directly or indirectly using this device, data processed both ways are also compared to conclude about the more reliable method.
International Symposium on Applied Geoinformatics 2021, 2022
Introduction/Background The contribution of trees to the mitigation of urban heat islands is a to... more Introduction/Background The contribution of trees to the mitigation of urban heat islands is a topic with current trend. Not only bin the processes of surface cooling, but also by providing shade for pedestrians and facades, urban trees act as a microclimate regulator. Even if the benefits due to trees are known, it is a challenge to quantify their role. In order to estimate this positive effect, climate models are developed. Simulating the energy balance at the scale of a street supposes to faithfully reproduce the geometry of the materials and geometries of the elements composing the street. Micro-climatic models are under development in the literature to reproduce the physical impact of buildings and trees on the microclimate, however the complexity to take into account all influencing parameters usually limit the application of the model to regional or city scales. At the scale of a district, the LASER/F model (LAtent SEnsible Radiation Fluxes) requires as input among other parameters, threedimensional models of buildings and trees (Kastendeuch et al., 2017). However, it raises questions about the level of detail and of accuracy of the expected buildings and tree models (Bournez et al., 2019).
Developments in the field of artificial intelligence have made great strides in the field of auto... more Developments in the field of artificial intelligence have made great strides in the field of automatic semantic segmentation, both in the 2D (image) and 3D spaces. Within the context of 3D recording technology it has also seen application in several areas, most notably in creating semantically rich point clouds which is usually performed manually. In this paper, we propose the introduction of deep learning-based semantic image segmentation into the photogrammetric 3D reconstruction and classification workflow. The main objective is to be able to introduce semantic classification at the beginning of the classical photogrammetric workflow in order to automatically create classified dense point clouds by the end of the said workflow. In this regard, automatic image masking depending on pre-determined classes were performed using a previously trained neural network. The image masks were then employed during dense image matching in order to constraint the process into the respective clas...
Developments in the field of artificial intelligence have made great strides in the field of auto... more Developments in the field of artificial intelligence have made great strides in the field of automatic semantic segmentation, both in the 2D (image) and 3D spaces. Within the context of 3D recording technology it has also seen application in several areas, most notably in creating semantically rich point clouds which is usually performed manually. In this paper, we propose the introduction of deep learning-based semantic image segmentation into the photogrammetric 3D reconstruction and classification workflow. The main objective is to be able to introduce semantic classification at the beginning of the classical photogrammetric workflow in order to automatically create classified dense point clouds by the end of the said workflow. In this regard, automatic image masking depending on pre-determined classes were performed using a previously trained neural network. The image masks were then employed during dense image matching in order to constraint the process into the respective clas...
Le suivi de l'evolution rapide des glaciers temperes est important pour des raisons economiqu... more Le suivi de l'evolution rapide des glaciers temperes est important pour des raisons economiques, de securite et d'indicateur local des effets du changement global du climat. Comparees aux mesures terrestres dispersees, les acquisitions d'images Radar a Synthese d'Ouverture (RSO ou SAR) permettent de suivre regulierement la dynamique des glaciers et apportent des mesures denses des parametres physiques qui sont necessaires pour detecter des changements significatifs et contraindre les modeles d'ecoulements des glaciers. L'interferometrie RSO ou les techniques alternatives peuvent etre appliquees pour mesurer des champs de deplacements qui peuvent etre de quelques decimetres par jour dans les Alpes. Les images satellitaires ERS1-2 ont ete utilisees pour obtenir des champs de vitesse, principalement en hiver a cause de la forte decorrelation temporelle en ete. La polarimetrie RSO peut augmenter le potentiel des observations des surfaces ou des sub-surfaces des g...
More and more uses and applications are being given to local climate zone (LCZ) maps, which descr... more More and more uses and applications are being given to local climate zone (LCZ) maps, which describe the structure of the urban and semi-urban areas. Among others, it is worth highlighting its use in studies of urban heat islands (UHI), sustainability and urban energy balance. Even if the classes are well described in the literature, it is difficult to estimate the general precision of these classification maps because the classification is highly dependent of the urban typology of the city under study. However, LCZ maps represent a reference in the field of urban climatology. This research work aims to make use of these maps to explain the strong influence of LCZ classes on land surface temperature (LST) and, consequently, on air temperature (AT). This kind of investigations will help us to explain the outliers observed in previous work between LST and AT at specific locations in the city of Strasbourg for the period 2012-2019. The LST data were obtained from the thermal infrared d...
Abstract Built heritage documentation involves the 3D modelling of the geometry (typically using ... more Abstract Built heritage documentation involves the 3D modelling of the geometry (typically using 3D computer graphics, photogrammetry and laser scanning techniques) and information management of semantic knowledge (i.e., using Geographic Information System (GIS) and ontology tools). The recent developed Building Information Modelling (BIM) technique combines 3D modelling and information management. One of its modern application is heritage documentation and has generated a new concept of Historic/Heritage Building Information Modelling (HBIM). This paper summarises the applications of these information techniques on the built heritage documentation. We utilise Web of Science Collection to monitor the publications on built heritage documentation. We analyse the research trend in heritage modelling by comparing the attention paid by researchers before and during the 2010s. The results show that photogrammetry is always the most popular method in heritage modelling. More and more works in heritage modelling have begun to use laser scanning, computer science, GIS and especially BIM techniques. Ontologies and 3D computer graphics are traditional ways for heritage documentation. Moreover, we pay attention to the roles of BIM on heritage documentation and conduct a detailed discussion on how to extend the HBIM capabilities by integrating with other techniques. The integration provides possible enhanced functions in HBIM, including accurate parametric modelling from computer graphics, automatic semantic segmentation of 3D point cloud from reality-based modelling, spatial information management and analysis by GIS, and knowledge modelling by ontology.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2020
In the context of building renovation, energy audits of buildings are performed in order to reduc... more In the context of building renovation, energy audits of buildings are performed in order to reduce energy consumption and greenhouse gas emissions. Infrared cameras allow analyzing precisely the energetic performances and the thermal comfort of a building and the analysis of thermal images of buildings represents a key step on the way to the reduction of energy consumption. In the last few years, the combination of thermal and metric information has been increasingly studied. The geometry provides the exact location of defects and enables accurate energy analysis. This paper focuses on the automatic analysis of facades point clouds with thermal attributes. The aim of our work is to extract windows and thermal bridges by considering both geometric and thermal features. The extraction of objects or zones of interest in thermal data consists in the detection of significant temperature variations. The developed approach, mainly based on the automatic analysis of histograms, is applied to a point cloud acquired by a Mobile Mapping Unit.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2019
In the cultural heritage field, several specialists like archaeologists, architects, geomaticians... more In the cultural heritage field, several specialists like archaeologists, architects, geomaticians, historians, etc. are used to work together. With the upcoming technologies allowing to capture efficiently data in the field, to digitize historical documents, to collect worldwide information related to the monuments under study, the wish to summarize all the sources of data (including the knowledge of the specialists) into one 3D model is a big challenge. In order to guarantee the reliability of the proposed reconstructed 3D model, it is of crucial importance to integrate the level of uncertainty assigned to it. From a geometric point of view, uncertainty is often defined, quantified and expressed with the help of statistical measures. However, for objects reconstructed based on archaeological assumptions, statistical measures are not appropriate. This paper focuses on the decomposition of 3D models into levels of uncertainties (LoUs) and on the best way to visualize them through two case studies: the castle of Kagenfels and the Horbourg-Wihr Castellum, both located in Alsace, France. The first one is well documented through still ongoing excavations around its remains, whereas the second one disappeared under the urbanization of the city. An approach enabling, on the 3D models, not only to quantify but also to visualize uncertainties coming from archaeological assumptions is addressed. Finally, the efficiency of the approach for qualifying the proposed 3D model of the reconstructed castle regarding its reliability is demonstrated.
ISPRS Journal of Photogrammetry and Remote Sensing, 2018
Urban leaf area measurement is crucial to properly determining the effect of urban trees on micro... more Urban leaf area measurement is crucial to properly determining the effect of urban trees on micro-climate regulation, heat island effect, building cooling, air quality improvement, and ozone formation. Previous works on the leaf area measurement have mainly focused on the stand level, although the presence of individual trees is more common than forests in urban areas. The only feasible ways for an operational non-destructive leaf area measurement, namely, optical indirect methods, are mostly limited in urban areas because light path is constantly intercepted by surrounding buildings or other objects. A terrestrial laser scanner (TLS), which can extract an individual tree by using its unique distance information, provides a possibility for indirectly measuring the leaf area index (LAI) in urban areas. However, indirect LAI measurement theory, which uses the cosine of an observation zenith angle for path-length correction, is incompatible for an individual tree because the representative projected area of LAI changes while the observation zenith angle changes, thus making the results incomparable and ambiguous. Therefore, we modified a path length distribution model for the leaf area measurement of an individual tree by replacing the traditional cosine path length correction for a continuous canopy with real path length distribution. We reconstructed the tree crown envelope from a TLS point cloud and calculated a real path length distribution through laser pulse-envelope intersections. Consequently, leaf area density was separated from the path length distribution model for leaf area calculation. Comparisons with reference measurement for an individual tree showed that the TLS-derived leaf area using the path length distribution is insensitive to the scanning resolution and agrees well with an allometric measurement with an overestimation from 5 m 2 to 18 m 2 (3-10%, respectively). Results from different stations are globally consistent, and using a weighted mean for different stations by sample numbers further improves the universality and efficiency of the proposed method. Further automation of the proposed method can facilitate a rapid and operational leaf area extraction of an individual tree for urban climate modeling.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2017
3D models of tree geometry are important for numerous studies, such as for urban planning or agri... more 3D models of tree geometry are important for numerous studies, such as for urban planning or agricultural studies. In climatology, tree models can be necessary for simulating the cooling effect of trees by estimating their evapotranspiration. The literature shows that the more accurate the 3D structure of a tree is, the more accurate microclimate models are. This is the reason why, since 2013, we have been developing an algorithm for the reconstruction of trees from terrestrial laser scanner (TLS) data, which we call TreeArchitecture. Meanwhile, new promising algorithms dedicated to tree reconstruction have emerged in the literature. In this paper, we assess the capacity of our algorithm and of two others-PlantScan3D and SimpleTree-to reconstruct the 3D structure of trees. The aim of this reconstruction is to be able to characterize the geometric complexity of trees, with different heights, sizes and shapes of branches. Based on a specific surveying workflow with a TLS, we have acquired dense point clouds of six different urban trees, with specific architectures, before reconstructing them with each algorithm. Finally, qualitative and quantitative assessments of the models are performed using reference tree reconstructions and field measurements. Based on this assessment, the advantages and the limits of every reconstruction algorithm are highlighted. Anyway, very satisfying results can be reached for 3D reconstructions of tree topology as well as of tree volume.
Contribution à la segmentation et à la modélisation 3D du milieu urbain à partir de nuages de poi... more Contribution à la segmentation et à la modélisation 3D du milieu urbain à partir de nuages de points Soutenue le 1 er décembre 2020
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2020
The lack of benchmarking data for the semantic segmentation of digital heritage scenarios is hamp... more The lack of benchmarking data for the semantic segmentation of digital heritage scenarios is hampering the development of automatic classification solutions in this field. Heritage 3D data feature complex structures and uncommon classes that prevent the simple deployment of available methods developed in other fields and for other types of data. The semantic classification of heritage 3D data would support the community in better understanding and analysing digital twins, facilitate restoration and conservation work, etc. In this paper, we present the first benchmark with millions of manually labelled 3D points belonging to heritage scenarios, realised to facilitate the development, training, testing and evaluation of machine and deep learning methods and algorithms in the heritage field. The proposed benchmark, available at http://archdataset.polito.it/, comprises datasets and classification results for better comparisons and insights into the strengths and weaknesses of different machine and deep learning approaches for heritage point cloud semantic segmentation, in addition to promoting a form of crowdsourcing to enrich the already annotated database.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2015
On the occasion of the millennium celebration of Strasbourg Cathedral, a transdisciplinary resear... more On the occasion of the millennium celebration of Strasbourg Cathedral, a transdisciplinary research group composed of archaeologists, surveyors, architects, art historians and a stonemason revised the 1966-1972 excavations under the St. Lawrence’s Chapel of the Cathedral having remains of Roman and medieval masonry. The 3D modeling of the Chapel has been realized based on the combination of conventional surveying techniques for the network creation, laser scanning for the model creation and photogrammetric techniques for the texturing of a few parts. According to the requirements and the end-user of the model, the level of detail and level of accuracy have been adapted and assessed for every floor. The basement has been acquired and modeled with more details and a higher accuracy than the other parts. Thanks to this modeling work, archaeologists can confront their assumptions to those of other disciplines by simulating constructions of other worship edifices on the massive stones co...
et mots clés Depuis plus d'une dizaine d'années, des mesures de vitesses d'écoulement sont effect... more et mots clés Depuis plus d'une dizaine d'années, des mesures de vitesses d'écoulement sont effectuées sur le glacier d'Argentière. En complétant avec des mesures plus ponctuelles réalisées lors des expériences MEGATOR, nous avons pu déterminer une vitesse de référence en un point de la zone d'accumulation. La connaissance de cette vitesse d'écoulement permet alors de lever l'ambiguïté de champs de déplacement calculés à partir de couples d'images radar à synthèse d'ouverture (RSO) interférométriques acquis par les satellites ERS-1/2. Ces interférogrammes permettent de déterminer des vitesses d'écoulement sur l'ensemble du glacier, qui elles-mêmes peuvent finalement être comparées à des mesures géodésiques in-situ. Les résultats étant très proches, la méthode est ainsi validée.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2021
The detection of openings based on point clouds is generally based on geometric features namely t... more The detection of openings based on point clouds is generally based on geometric features namely the X, Y and Z coordinates of points. Existing methods exploit geometric features but ignore most of the time other attributes as colour and intensity. Such information may be however particularly interesting to recognise and segment openings in facades. In this paper, the use of radiometric information, namely colour and intensity, is investigated for the segmentation of windows from façade point clouds. The assumption is made that windows are significantly different in terms of materials and colours to be distinguished from facade walls. The exploitation of colour and intensity are considered separately. A histogram analysis method is proposed for the exploitation of intensity information whereas a region growing method based on colorimetric distances is considered for the exploitation of colours. In order to refine the results, geometric information, and more precisely depth of points with regards to façade walls, are combined to radiometric information. Several combinations of attributes are considered and provide promising results for windows segmentation based on point clouds.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2020
With their high recording rate of hundreds of thousands of points acquired per second, speed of e... more With their high recording rate of hundreds of thousands of points acquired per second, speed of execution and a remote acquisition mode, SLAM based mobile mapping systems (MMS) are a very powerful solution for capturing 3D point clouds in real time, simply by walking in the area of interest. Regarding indoor surveys, these MMS have been integrated in handheld or backpack solutions and become fast scanning sensors. Despite their advantages, the geometric accuracy of 3D point clouds guaranteed with these sensors is lower than the one reachable with static TLS. In this paper the effectiveness of two recent mobile mapping systems namely the GeoSLAM ZEB-REVO RT and the more recent GreenValley LiBackPack C50 is investigated for indoor surveys. In order to perform a reliable assessment study, several datasets produced with each sensor are compared to the high-cost georeferenced point cloud obtained with static laser scanning target-based technique.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2019
In the context of building renovation, infrared (IR) cameras are widely used to perform the energ... more In the context of building renovation, infrared (IR) cameras are widely used to perform the energy audit of buildings. They allow analysing precisely the energetic performances of existing buildings and thermal analyses represent a key step for the reduction of energy consumption. They are also used to assess the thermal comfort of people living or working in a building. Building Information Models (BIM) are widespread to plan the rehabilitation of existing buildings and laser scanning is now commonly used to capture the geometry of buildings for as-built BIM creation. The combination of thermographic and geometric data presents a high number and variety of applications (Lagüela and Díaz-Vilariño, 2016). However, geometric and thermal information are generally acquired separately by different building stakeholders and thermal analyses are performed with independence of geometry. In this paper, the combination of thermal and geometric information is investigated for indoor of buildings. The aim of the project is to create 3D thermographic point clouds based on data acquired by a laser scanner and a thermal camera. Based on these point clouds, BIM models might be enriched with thermal information through the scan-to-BIM process.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2017
The use of Terrestrial Laser Scanner (TLS) tends to become a solution in many research areas rela... more The use of Terrestrial Laser Scanner (TLS) tends to become a solution in many research areas related to large scale surveying. Meanwhile, the technological advances combined with the investigation of user needs have brought to the design of innovative devices known as scanning total stations. Such instruments merge in a unique hardware both scanning and surveying facilities. Even if their scanning rate is often reduced compared to conventional TLS, they make it possible to directly georeference laser scanning projects and to complete them with measurements of individual points of interest. The recent Trimble SX10 which was launched on the market in early October 2016 has been tested and some experiences carried out with it are reported in this paper. The analyses mainly focus on the survey of a building facade. Next to laser scanning survey, a photogrammetry campaign using an Unmanned Aerial Vehicle (UAV) has been carried out. These different datasets are used to assess the Trimble SX10 issued point clouds through a set of comparisons. Since georeferencing is possible either directly or indirectly using this device, data processed both ways are also compared to conclude about the more reliable method.
International Symposium on Applied Geoinformatics 2021, 2022
Introduction/Background The contribution of trees to the mitigation of urban heat islands is a to... more Introduction/Background The contribution of trees to the mitigation of urban heat islands is a topic with current trend. Not only bin the processes of surface cooling, but also by providing shade for pedestrians and facades, urban trees act as a microclimate regulator. Even if the benefits due to trees are known, it is a challenge to quantify their role. In order to estimate this positive effect, climate models are developed. Simulating the energy balance at the scale of a street supposes to faithfully reproduce the geometry of the materials and geometries of the elements composing the street. Micro-climatic models are under development in the literature to reproduce the physical impact of buildings and trees on the microclimate, however the complexity to take into account all influencing parameters usually limit the application of the model to regional or city scales. At the scale of a district, the LASER/F model (LAtent SEnsible Radiation Fluxes) requires as input among other parameters, threedimensional models of buildings and trees (Kastendeuch et al., 2017). However, it raises questions about the level of detail and of accuracy of the expected buildings and tree models (Bournez et al., 2019).
Developments in the field of artificial intelligence have made great strides in the field of auto... more Developments in the field of artificial intelligence have made great strides in the field of automatic semantic segmentation, both in the 2D (image) and 3D spaces. Within the context of 3D recording technology it has also seen application in several areas, most notably in creating semantically rich point clouds which is usually performed manually. In this paper, we propose the introduction of deep learning-based semantic image segmentation into the photogrammetric 3D reconstruction and classification workflow. The main objective is to be able to introduce semantic classification at the beginning of the classical photogrammetric workflow in order to automatically create classified dense point clouds by the end of the said workflow. In this regard, automatic image masking depending on pre-determined classes were performed using a previously trained neural network. The image masks were then employed during dense image matching in order to constraint the process into the respective clas...
Developments in the field of artificial intelligence have made great strides in the field of auto... more Developments in the field of artificial intelligence have made great strides in the field of automatic semantic segmentation, both in the 2D (image) and 3D spaces. Within the context of 3D recording technology it has also seen application in several areas, most notably in creating semantically rich point clouds which is usually performed manually. In this paper, we propose the introduction of deep learning-based semantic image segmentation into the photogrammetric 3D reconstruction and classification workflow. The main objective is to be able to introduce semantic classification at the beginning of the classical photogrammetric workflow in order to automatically create classified dense point clouds by the end of the said workflow. In this regard, automatic image masking depending on pre-determined classes were performed using a previously trained neural network. The image masks were then employed during dense image matching in order to constraint the process into the respective clas...
Le suivi de l'evolution rapide des glaciers temperes est important pour des raisons economiqu... more Le suivi de l'evolution rapide des glaciers temperes est important pour des raisons economiques, de securite et d'indicateur local des effets du changement global du climat. Comparees aux mesures terrestres dispersees, les acquisitions d'images Radar a Synthese d'Ouverture (RSO ou SAR) permettent de suivre regulierement la dynamique des glaciers et apportent des mesures denses des parametres physiques qui sont necessaires pour detecter des changements significatifs et contraindre les modeles d'ecoulements des glaciers. L'interferometrie RSO ou les techniques alternatives peuvent etre appliquees pour mesurer des champs de deplacements qui peuvent etre de quelques decimetres par jour dans les Alpes. Les images satellitaires ERS1-2 ont ete utilisees pour obtenir des champs de vitesse, principalement en hiver a cause de la forte decorrelation temporelle en ete. La polarimetrie RSO peut augmenter le potentiel des observations des surfaces ou des sub-surfaces des g...
More and more uses and applications are being given to local climate zone (LCZ) maps, which descr... more More and more uses and applications are being given to local climate zone (LCZ) maps, which describe the structure of the urban and semi-urban areas. Among others, it is worth highlighting its use in studies of urban heat islands (UHI), sustainability and urban energy balance. Even if the classes are well described in the literature, it is difficult to estimate the general precision of these classification maps because the classification is highly dependent of the urban typology of the city under study. However, LCZ maps represent a reference in the field of urban climatology. This research work aims to make use of these maps to explain the strong influence of LCZ classes on land surface temperature (LST) and, consequently, on air temperature (AT). This kind of investigations will help us to explain the outliers observed in previous work between LST and AT at specific locations in the city of Strasbourg for the period 2012-2019. The LST data were obtained from the thermal infrared d...
Abstract Built heritage documentation involves the 3D modelling of the geometry (typically using ... more Abstract Built heritage documentation involves the 3D modelling of the geometry (typically using 3D computer graphics, photogrammetry and laser scanning techniques) and information management of semantic knowledge (i.e., using Geographic Information System (GIS) and ontology tools). The recent developed Building Information Modelling (BIM) technique combines 3D modelling and information management. One of its modern application is heritage documentation and has generated a new concept of Historic/Heritage Building Information Modelling (HBIM). This paper summarises the applications of these information techniques on the built heritage documentation. We utilise Web of Science Collection to monitor the publications on built heritage documentation. We analyse the research trend in heritage modelling by comparing the attention paid by researchers before and during the 2010s. The results show that photogrammetry is always the most popular method in heritage modelling. More and more works in heritage modelling have begun to use laser scanning, computer science, GIS and especially BIM techniques. Ontologies and 3D computer graphics are traditional ways for heritage documentation. Moreover, we pay attention to the roles of BIM on heritage documentation and conduct a detailed discussion on how to extend the HBIM capabilities by integrating with other techniques. The integration provides possible enhanced functions in HBIM, including accurate parametric modelling from computer graphics, automatic semantic segmentation of 3D point cloud from reality-based modelling, spatial information management and analysis by GIS, and knowledge modelling by ontology.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2020
In the context of building renovation, energy audits of buildings are performed in order to reduc... more In the context of building renovation, energy audits of buildings are performed in order to reduce energy consumption and greenhouse gas emissions. Infrared cameras allow analyzing precisely the energetic performances and the thermal comfort of a building and the analysis of thermal images of buildings represents a key step on the way to the reduction of energy consumption. In the last few years, the combination of thermal and metric information has been increasingly studied. The geometry provides the exact location of defects and enables accurate energy analysis. This paper focuses on the automatic analysis of facades point clouds with thermal attributes. The aim of our work is to extract windows and thermal bridges by considering both geometric and thermal features. The extraction of objects or zones of interest in thermal data consists in the detection of significant temperature variations. The developed approach, mainly based on the automatic analysis of histograms, is applied to a point cloud acquired by a Mobile Mapping Unit.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2019
In the cultural heritage field, several specialists like archaeologists, architects, geomaticians... more In the cultural heritage field, several specialists like archaeologists, architects, geomaticians, historians, etc. are used to work together. With the upcoming technologies allowing to capture efficiently data in the field, to digitize historical documents, to collect worldwide information related to the monuments under study, the wish to summarize all the sources of data (including the knowledge of the specialists) into one 3D model is a big challenge. In order to guarantee the reliability of the proposed reconstructed 3D model, it is of crucial importance to integrate the level of uncertainty assigned to it. From a geometric point of view, uncertainty is often defined, quantified and expressed with the help of statistical measures. However, for objects reconstructed based on archaeological assumptions, statistical measures are not appropriate. This paper focuses on the decomposition of 3D models into levels of uncertainties (LoUs) and on the best way to visualize them through two case studies: the castle of Kagenfels and the Horbourg-Wihr Castellum, both located in Alsace, France. The first one is well documented through still ongoing excavations around its remains, whereas the second one disappeared under the urbanization of the city. An approach enabling, on the 3D models, not only to quantify but also to visualize uncertainties coming from archaeological assumptions is addressed. Finally, the efficiency of the approach for qualifying the proposed 3D model of the reconstructed castle regarding its reliability is demonstrated.
ISPRS Journal of Photogrammetry and Remote Sensing, 2018
Urban leaf area measurement is crucial to properly determining the effect of urban trees on micro... more Urban leaf area measurement is crucial to properly determining the effect of urban trees on micro-climate regulation, heat island effect, building cooling, air quality improvement, and ozone formation. Previous works on the leaf area measurement have mainly focused on the stand level, although the presence of individual trees is more common than forests in urban areas. The only feasible ways for an operational non-destructive leaf area measurement, namely, optical indirect methods, are mostly limited in urban areas because light path is constantly intercepted by surrounding buildings or other objects. A terrestrial laser scanner (TLS), which can extract an individual tree by using its unique distance information, provides a possibility for indirectly measuring the leaf area index (LAI) in urban areas. However, indirect LAI measurement theory, which uses the cosine of an observation zenith angle for path-length correction, is incompatible for an individual tree because the representative projected area of LAI changes while the observation zenith angle changes, thus making the results incomparable and ambiguous. Therefore, we modified a path length distribution model for the leaf area measurement of an individual tree by replacing the traditional cosine path length correction for a continuous canopy with real path length distribution. We reconstructed the tree crown envelope from a TLS point cloud and calculated a real path length distribution through laser pulse-envelope intersections. Consequently, leaf area density was separated from the path length distribution model for leaf area calculation. Comparisons with reference measurement for an individual tree showed that the TLS-derived leaf area using the path length distribution is insensitive to the scanning resolution and agrees well with an allometric measurement with an overestimation from 5 m 2 to 18 m 2 (3-10%, respectively). Results from different stations are globally consistent, and using a weighted mean for different stations by sample numbers further improves the universality and efficiency of the proposed method. Further automation of the proposed method can facilitate a rapid and operational leaf area extraction of an individual tree for urban climate modeling.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2017
3D models of tree geometry are important for numerous studies, such as for urban planning or agri... more 3D models of tree geometry are important for numerous studies, such as for urban planning or agricultural studies. In climatology, tree models can be necessary for simulating the cooling effect of trees by estimating their evapotranspiration. The literature shows that the more accurate the 3D structure of a tree is, the more accurate microclimate models are. This is the reason why, since 2013, we have been developing an algorithm for the reconstruction of trees from terrestrial laser scanner (TLS) data, which we call TreeArchitecture. Meanwhile, new promising algorithms dedicated to tree reconstruction have emerged in the literature. In this paper, we assess the capacity of our algorithm and of two others-PlantScan3D and SimpleTree-to reconstruct the 3D structure of trees. The aim of this reconstruction is to be able to characterize the geometric complexity of trees, with different heights, sizes and shapes of branches. Based on a specific surveying workflow with a TLS, we have acquired dense point clouds of six different urban trees, with specific architectures, before reconstructing them with each algorithm. Finally, qualitative and quantitative assessments of the models are performed using reference tree reconstructions and field measurements. Based on this assessment, the advantages and the limits of every reconstruction algorithm are highlighted. Anyway, very satisfying results can be reached for 3D reconstructions of tree topology as well as of tree volume.
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Papers by Tania Landes