Ludwig Hoegner

Ludwig Hoegner
Technische Universität München | TUM · Chair of Photogrammetry and Remote Sensing

Dr.-Ing.

About

108
Publications
25,669
Reads
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1,064
Citations
Citations since 2016
62 Research Items
927 Citations
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2016201720182019202020212022050100150200
Introduction
Photogrammetry and Remote Sensing with focus on 3d reconstruction of urban objects and trees, change detection on buildings, hang slides and rock falls, indoor 3d reconstruction and texturing, theral infrared texture generation and object extraction.
Additional affiliations
January 2006 - present
Technische Universität München
Position
  • PostDoc Position

Publications

Publications (108)
Article
Full-text available
Visibility analysis plays a vital role in the design and placing of traffic signs in the urban street environment. This work investigates the occlusion detection of traffic lights and traffic signs caused by vegetation. The presented analysis method is built upon the inputs from the expected situation reflected by a highly detailed 3D city model an...
Article
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Semantic 3D building models are widely available and used in numerous applications. Such 3D building models display rich semantics but no façade openings, chiefly owing to their aerial acquisition techniques. Hence, refining models’ façades using dense, street-level, terrestrial point clouds seems a promising strategy. In this paper, we propose a m...
Article
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Semantic 3D building models are provided by public authorities and can be used in applications, such as urban planning, simulations, navigation, and many others. Since large-scale 3D models are typically derived from top-view digital surface models (DSM), they can have detailed roof structures but render planes for façade elements. Furthermore, bui...
Article
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This contribution presents a method for extracting a 3D model of facades and windows from a point cloud. The point cloud is segmented based on a voxel octree, in which the facades are sought as planes. These can be used to filter out potential window points within the building, which are then analysed on their visibility by checking the occupancy g...
Article
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Gravitational mass movements represent a significant hazard potential in Alpine regions. Due to climate change and an associated increases in extreme weather events, this risk is growing. For a better predictability of such events and the monitoring of affected areas, a precise determination of the ongoing movements is necessary. In this paper, a m...
Article
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Point clouds are widely regarded as one of the best dataset types for urban mapping purposes. Hence, point cloud datasets are commonly investigated as benchmark types for various urban interpretation methods. Yet, few researchers have addressed the use of point cloud benchmarks for façade segmentation. Robust façade segmentation is becoming a key f...
Preprint
Full-text available
Der moderne Automobilbau, insbesondere im Premiumsegment, setzt äußerst enge Toleranzen hinsichtlich der Oberflächengüte des Endproduktes voraus. Beginnend mit der Blechumformung im Presswerk, über den Karosseriebau, bis hin zur Lackierung und Endmontage, müssen etwaige Oberflächenfehler im teilweise einstelligen Mikrometerbereich detektiert, klass...
Article
As the key to the construction progress monitoring, methods and strategies for change detection using 3D point clouds from various sources have been investigated for years. However, how to achieve object-level change detection with uncertainty evaluation is still an unsolved topic. Occlusions and noise in 3D points and other attribute information,...
Article
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Trees play an important role in the complex system of urban environments. Their benefits to environment and health are manifold. Yet, especially near streets, the traffic can be impaired by a limited clearance. Even injuries could be caused by breaking tree parts. Hence, it is important to capture the trees in the frame of a tree cadastre and to en...
Article
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In our daily lives, trees can be seen as the tallest and most noticeable representatives of the plant kingdom. Especially in urban areas, the individual tree is of high significance and responsible for a manifold of positive effects on the environment and residents. In the context of urban tree registers and thus monitoring of urban vegetation, we...
Article
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When purchasing a premium car for a substantial sum, first impressions count. Key to that first impression is a flawless exterior appearance, something self-explanatory for the customer, but a far greater challenge for production than one might initially assume. Fortunately, photogrammetric technologies and evaluation methods are enabling an ever g...
Article
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Nowadays, the number of connected devices providing unstructured data is rapidly rising. These devices acquire data with a temporal and spatial resolution at an unprecedented level creating an influx of geoinformation which, however, lacks semantic information. Simultaneously, structured datasets like semantic 3D city models are widely available an...
Article
Point cloud registration is invariably an essential and challenging task in the fields of photogrammetry and computer vision to align multiple point clouds to a united reference frame. In this paper, we propose a novel global registration method using a robust phase correlation method for registration of low-overlapping point clouds, which is less...
Article
Buildings take a large proportion of the total energy consumption in the city area in winter, therefore Thermal Infrared (TIR) images are widely used to evaluate the energy consumption and leakage of the building. To overcome the difficulties of image interpretation and occlusion in TIR images, utilizing thermal information in 3D structures that fu...
Article
Plane segmentation is a simple yet essential processing step for using 3D point clouds in applications such as temporal data registration and object modeling. The performance of traditional plane segmentation algorithms, especially when addressing photogrammetric point clouds, is significantly limited by factors including the errors of the point po...
Article
Registration of multi-temporal data is an important task when conducting construction monitoring and analysis using 3D point clouds acquired at different time points. However, due to the complexity of scenes in construction sites and the intrinsic attributes of the datasets (e.g., noise, outliers, and uneven densities), the registration of multi-te...
Article
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Image registration is a fundamental issue in photogrammetry and remote sensing, which targets to find the alignment between different images. Recently, registration of images from difference sensors become the hot topic. The registered images from different sensors are able to offer additional information, which help with different tasks like segme...
Article
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This contribution discusses the accuracy and the applicability of Photogrammetric point clouds based on dense image matching for the monitoring of gravitational mass movements caused by crevices. Four terrestrial image sequences for three different time epochs have been recorded and oriented using ground control point in a local reference frame. Fo...
Article
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Registration of multiple point clouds acquired via terrestrial laser scanning (TLS) is usually compulsory to obtain the scanned data covering a whole urban scene. However, the automated processing of aligning multiple scans is still a concern because of the complex urban environment. To this end, we propose a fast and sturdy estimation of 3D shifts...
Article
Full-text available
The semantic labeling of the urban area is an essential but challenging task for a wide variety of applications such as mapping, navigation, and monitoring. The rapid advance in Light Detection and Ranging (LiDAR) systems provides this task with a possible solution using 3D pointclouds, which are accessible, affordable, accurate, and applicable. Am...
Article
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In the past decade, a vast amount of strategies, methods, and algorithms have been developed to explore the semantic interpretation of 3D point clouds for extracting desirable information. To assess the performance of the developed algorithms or methods, public standard benchmark datasets should invariably be introduced and used, which serve as an...
Article
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Interpretation of 3D scene through LiDAR point clouds has been a hot research topic for decades. To utilize measured points in the scene, assigning unique tags to the points of the scene with labels linking to individual objects plays a crucial role in the analysis process. In this paper, we present a supervised classification approach for the sema...
Article
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This work proposes an approach for semantic classification of an outdoor-scene point cloud acquired with a high precision Mobile Mapping System (MMS), with major goal to contribute to the automatic creation of High Definition (HD) Maps. The automatic point labeling is achieved by utilizing the combination of a feature-based approach for semantic cl...
Article
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In this work, we discussed how to directly combine thermal infrared image (TIR) and the point cloud without additional assistance from GCPs or 3D models. Specifically, we propose a point-based co-registration process for combining the TIR image and the point cloud for the buildings. The keypoints are extracted from images and point clouds via primi...
Article
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Reconstruction of dense photogrammetric point clouds is often based on depth estimation of rectified image pairs by means of pixel-wise matching. The main drawback lies in the high computational complexity compared to that of the relatively straightforward task of laser triangulation. Dense image matching needs oriented and rectified images and loo...
Article
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This paper proposes a method to get semantic information of changes in bathymetric point clouds. This method aims for assigning labels to river ground points which determine if either the point can be compared with a reference DEM, if there are no data in the reference or if there are no water points inside the new Data of wet areas of the referenc...
Conference Paper
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With the rapid development of subpixel matching algorithms, the estimation of image shifts with an accuracy of higher than 0.05 pixels is achieved, which makes the narrow baseline stereovision possible. Based on the subpixel matching algorithm using the robust phase correlation (PC), in this work, we present a novel hierarchical and adaptive dispar...
Article
To ensure complete coverage when measuring a large-scale urban area, pairwise registration between point clouds acquired via terrestrial laser scanning or stereo image matching is usually necessary when there is insufficient georeferencing information from additional GNSS and INS sensors. In this paper, we propose a semi-automatic and target-less m...
Article
This article proposes a method for registration of two different point clouds with different point densities and noise recorded by airborne sensors in rural areas. In particular, multi-sensor point clouds with different point densities are considered. The proposed method is marker-less and uses segmented ground areas for registration.Therefore, the...
Article
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This paper discusses the automatic generation of thermal infrared ortho image mosaics and the extraction of solar cells from these ortho image mosaics. Image sequences are recorded by a thermal infrared (TIR) camera mounted on a remotely piloted aerial system (RPAS). The image block is relatively oriented doing a bundle block adjustment and transfe...
Article
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Obtaining accurate 3D descriptions in the thermal infrared (TIR) is a quite challenging task due to the low geometric resolutions of TIR cameras and the low number of strong features in TIR images. Combining the radiometric information of the thermal infrared with 3D data from another sensor is able to overcome most of the limitations in the 3D geo...
Conference Paper
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This paper shows a method to register point clouds from images of UAV-mounted airborne cameras as well as airborne laser scanner data. The focus is a general technique which does rely neither on linear or planar structures nor on the point cloud density. Therefore, the proposed approach is also suitable for rural areas and water bodies captured via...
Article
Segmentation is a fundamental step for parsing the point clouds of 3D scenes, which normally contain a wide variety of complex objects and structures with a large amount of points. In this paper, we propose a voxel-based point cloud segmentation method using Gestalt principles under a hierarchical clustering framework, allowing a completely automat...
Article
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In this work, we propose a classification method designed for the labeling of MLS point clouds, with detrended geometric features extracted from the points of the supervoxel-based local context. To achieve the analysis of 3D objects scenes, acquired points of the scene should be tagged with individual labels of different classes. Thus, assigning a...
Article
In this paper, we report a novel strategy for segmenting 3D point clouds using a voxel structure and graph-based clustering with perceptual grouping laws. It provides a completely automatic solution for partitioning point clouds of man-made infrastructure. Two different segmentation methods using voxel and supervoxel structures are presented and ev...
Article
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Visual SLAM algorithms allow localizing the camera by mapping its environment by a point cloud based on visual cues. To obtain the camera locations in a metric coordinate system, the metric scale of the point cloud has to be known. This contribution describes a method to calculate the metric scale for a point cloud of an indoor environment, like a...
Conference Paper
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This paper presents a method to register photogrammetric point clouds generated from optical images acquired by UAV and aerial LIDAR point clouds. Normally, the registration of two airborne scans of the same scene is solved by the use of control points and the direct registration using GNSS and INS information. However, the registration of multi-se...
Conference Paper
In this work, we propose a novel way of generating ground truth dataset for analyzing point cloud from different sensors and validation of algorithms. Instead of directly label the 3D points with time consuming manual work, a multi-resolution 3D voxel grid for the testing site is generated. Then, with the help of a set of basic labeled points, we c...
Article
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In this work, we report a novel way of generating ground truth dataset for analyzing point cloud from different sensors and the validation of algorithms. Instead of directly labeling large amount of 3D points requiring time consuming manual work, a multi-resolution 3D voxel grid for the testing site is generated. Then, with the help of a set of bas...
Article
Two workflows for mobile thermal mapping including geometric camera calibration, automatic image orientation, 3D reconstruction and extraction of textures of building façades from thermal IR image sequences are introduced. In the first method, a coregistration of a terrestrial image sequence is done with a given 3D building model with the 3D buildi...
Article
Construction site is the place of constructing buildings or infrastructures, showing very dynamic behaviors in changes and including plenty of complex objects. For recognizing building structures and other objects (e.g., workers and equipment) from 3D measurements (e.g., point clouds), the segmentation is normally required. Here, we propose a voxel...
Article
Scaffolds always act as disturbances when reconstructing the 3D scene of the construction site due to occlusions, similarities with buildings in color and height as well as their adjacent positions to wall surfaces. Since scaffolds are commonly utilized to assist the construction and maintenance of building structures, professionals can estimate th...
Article
Full-text available
For obtaining a full coverage of 3D scans in a large-scale urban area, the registration between point clouds acquired via terrestrial laser scanning (TLS) is normally mandatory. However, due to the complex urban environment, the automatic registration of different scans is still a challenging problem. In this work, we propose an automatic marker fr...
Article
The research herein presents a new approach for extracting building roofs using a robust voxel-based region growing segmentation method. The proposed approach exploits the fact that the roof of the building consists of planar surfaces and has distinctive geometric features than other kinds of objects. Based on this assumption, we present a method u...
Article
Full-text available
Point cloud segmentation and classification is currently a research highlight. Methods in this field create labelled data, where each point has additional class information. Current approaches are to generate a graph on the basis of all points in the point cloud, calculate or learn descriptors and train a matcher for the descriptor to the correspon...
Article
Full-text available
Segmentation is the fundamental step for recognizing and extracting objects from point clouds of 3D scene. In this paper, we present a strategy for point cloud segmentation using voxel structure and graph-based clustering with perceptual grouping laws, which allows a learning-free and completely automatic but parametric solution for segmenting 3D p...
Article
We propose a workflow for extracting geometric primitives, including linear, planar, and cylindrical objects, from point clouds of the construction site, using a novel segmentation- and recognition- based strategy. The entire point cloud is firstly organized by an octree-based voxel structure. The proposed voxel- and graph-based segmentation (VGS)...
Conference Paper
Full-text available
Der Beitrag untersucht die Leistungsfähigkeit der Photogrammetrie zur 3D-Rekonstruktion von Biberdämmen und beschreibt einen geeigneten Ablauf für die Datenerfassung und Prozessierung. Als Datengrundlage dienen Multikopter-Aufnahmen sowie terrestrische Aufnahmen des Biberreviers Glonn/Erdweg, die im Frühjahr 2016 erstellt wurden. Im Zuge der photog...
Conference Paper
This paper discusses methods on 3D reconstruction from ordered and unordered image sets in the visible RGB spectrum and the thermal infrared (TIR) spectrum. The 3D reconstruction is done detecting feature points in images and assigning the corresponding homologoues point. A bundle block adjustment with and without preknowledge of the camera orienta...
Conference Paper
This paper presents an approach for the classification of photogrammetric point clouds of scaffolding components in a construction site, aiming at making a preparation for the automatic monitoring of construction site by reconstructing an as-built Building Information Model (as-built BIM). The points belonging to tubes and toeboards of scaffolds wi...
Article
Full-text available
Stereo camera systems in cars are often used to estimate the distance of other road users from the car. This information is important to improve road safety. Such camera systems are typically mounted behind the windshield of the car. In this contribution, the influence of the windshield on the estimated distance values is analyzed. An offline stere...
Article
Full-text available
Stereo camera systems in cars are often used to estimate the distance of other road users from the car. This information is important to improve road safety. Such camera systems are typically mounted behind the windshield of the car. In this contribution, the influence of the windshield on the estimated distance values is analyzed. An offline stere...
Article
This paper presents an approach for the classification of photogrammetric point clouds of scaffolding components in a construction site, aiming at making a preparation for the automatic monitoring of construction site by reconstructing an as-built Building Information Model (as-built BIM). The points belonging to tubes and toeboards of scaffolds wi...
Article
This paper presents an approach for the classification of photogrammetric point clouds of scaffolding components in a construction site, aiming at making a preparation for the automatic monitoring of construction site by reconstructing an as-built Building Information Model (as-built BIM). The points belonging to tubes and toeboards of scaffolds wi...
Article
This paper discusses the automatic coregistration and fusion of 3d point clouds generated from aerial image sequences and corresponding thermal infrared (TIR) images. Both RGB and TIR images have been taken from a RPAS platform with a predefined flight path where every RGB image has a corresponding TIR image taken from the same position and with th...
Article
Full-text available
This paper discusses the automatic coregistration and fusion of 3d point clouds generated from aerial image sequences and corresponding thermal infrared (TIR) images. Both RGB and TIR images have been taken from a RPAS platform with a predefined flight path where every RGB image has a corresponding TIR image taken from the same position and with th...
Conference Paper
Full-text available
This contribution presents a project for 3D modelling and analysis of a valley floor for hydrological simulations. An RPAS (Remotely Piloted Aerial System) is used to mount either a high-resolution photogrammetric camera or a thermal infrared camera in two different, consecutive flights recording an image sequence. The images of the photogrammetric...
Article
Palm trees play an important role as they are widely used in a variety of products including oil and bio-fuel. Increasing demand and growing cultivation have created a necessity in planned farming and the monitoring different aspects like inventory keeping, health, size etc. The large cultivation regions of palm trees motivate the use of remote sen...
Article
Full-text available
Palm trees play an important role as they are widely used in a variety of products including oil and bio-fuel. Increasing demand and growing cultivation have created a necessity in planned farming and the monitoring different aspects like inventory keeping, health, size etc. The large cultivation regions of palm trees motivate the use of remote sen...
Conference Paper
This paper discusses the accuracies of two methods for automatic image orientation, 3D reconstruction, and extraction of textures of building facades from thermal IR image sequences. The first method uses the image sequence and camera calibration information only to reconstruct the scene in model coordinates and coregisters this model to a given 3D...
Article
Full-text available
Today, cameras mounted in vehicles are used to observe the driver as well as the objects around a vehicle. In this article, an outline of a concept for image based recognition of dynamic traffic situations is shown. A dynamic traffic situation will be described by road users and their intentions. Images will be taken by a vehicle fleet and aggregat...
Article
This contribution is focused on the selection of building textures extracted from thermal infrared (TIR) image sequences acquired both from terrestrial and aerial platforms by introducing a quality assessment. Extracted quality features are completeness of the texture, projection accuracy, viewing angle, and geometric resolution. The calculation of...
Article
Full-text available
This paper discusses the automatic texturing of building facades from thermal infrared image sequences. A fully automatic method is presented to refine GPS based positions estimating relative orientations of the image sequences including a given building model in a bundle adjustment process. The resulting refined orientation parameters are used to...
Article
Full-text available
For many research applications like water resources evaluation, determination of glacier specific changes, and for calculation of the past and future contribution of glaciers to sea-level change, parameters about the size and spatial distribution of glaciers is crucial. In this paper, an automatic method for determination of glacier surface area us...
Article
Full-text available
The Silences of the Archives, the Reknown of the Story. The Martin Guerre affair has been told many times since Jean de Coras and Guillaume Lesueur published their stories in 1561. It is in many ways a perfect intrigue with uncanny resemblance, persuasive deception and a surprizing end when the two Martin stood face to face, memory to memory, befor...