scholarly journals A novel geometry image to accurately represent a surface by preserving mesh topology

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sheng Zeng ◽  
Guohua Geng ◽  
Hongjuan Gao ◽  
Mingquan Zhou
Keyword(s):  
Spectral Characteristics ◽  
3D Models ◽  
Surface Model ◽  
Sampling Errors ◽  
Rounding Errors ◽  
Point Distribution ◽  
3D Mesh ◽  
Connected Surface ◽  
One To One ◽  
Geometry Image

AbstractGeometry images parameterise a mesh with a square domain and store the information in a single chart. A one-to-one correspondence between the 2D plane and the 3D model is convenient for processing 3D models. However, the parameterised vertices are not all located at the intersection of the gridlines the existing geometry images. Thus, errors are unavoidable when a 3D mesh is reconstructed from the chart. In this paper, we propose parameterise surface onto a novel geometry image that preserves the constraint of topological neighbourhood information at integer coordinate points on a 2D grid and ensures that the shape of the reconstructed 3D mesh does not change from supplemented image data. We find a collection of edges that opens the mesh into simply connected surface with a single boundary. The point distribution with approximate blue noise spectral characteristics is computed by capacity-constrained delaunay triangulation without retriangulation. We move the vertices to the constrained mesh intersection, adjust the degenerate triangles on a regular grid, and fill the blank part by performing a local affine transformation between each triangle in the mesh and image. Unlike other geometry images, the proposed method results in no error in the reconstructed surface model when floating-point data are stored in the image. High reconstruction accuracy is achieved when the xyz positions are in a 16-bit data format in each image channel because only rounding errors exist in the topology-preserving geometry images, there are no sampling errors. This method performs one-to-one mapping between the 3D surface mesh and the points in the 2D image, while foldovers do not appear in the 2D triangular mesh, maintaining the topological structure. This also shows the potential of using a 2D image processing algorithm to process 3D models.

scholarly journals UNDERWATER PHOTOGRAMMETRY DIGITAL SURFACE MODEL (DSM) OF THE SUBMERGED SITE OF THE ANCIENT LIGHTHOUSE NEAR QAITBAY FORT IN ALEXANDRIA, EGYPT

2019 ◽  
Vol XLII-2/W10 ◽  
pp. 1-8 ◽  
Author(s):  
M. Abdelaziz ◽  
M. Elsayed
Keyword(s):  
3D Model ◽  
Low Cost ◽  
Data Gathering ◽  
Archaeological Site ◽  
3D Models ◽  
Surface Model ◽  
Digital Surface Model ◽  
Architectural Elements ◽  
3D Photogrammetry ◽  
First Time

<p><strong>Abstract.</strong> Underwater photogrammetry in archaeology in Egypt is a completely new experience applied for the first time on the submerged archaeological site of the lighthouse of Alexandria situated on the eastern extremity of the ancient island of Pharos at the foot of Qaitbay Fort at a depth of 2 to 9 metres. In 2009/2010, the CEAlex launched a 3D photogrammetry data-gathering programme for the virtual reassembly of broken artefacts. In 2013 and the beginning of 2014, with the support of the Honor Frost Foundation, methods were developed and refined to acquire manual photographic data of the entire underwater site of Qaitbay using a DSLR camera, simple and low cost materials to obtain a digital surface model (DSM) of the submerged site of the lighthouse, and also to create 3D models of the objects themselves, such as statues, bases of statues and architectural elements. In this paper we present the methodology used for underwater data acquisition, data processing and modelling in order to generate a DSM of the submerged site of Alexandria’s ancient lighthouse. Until 2016, only about 7200&amp;thinsp;m<sup>2</sup> of the submerged site, which exceeds more than 13000&amp;thinsp;m<sup>2</sup>, was covered. One of our main objectives in this project is to georeference the site since this would allow for a very precise 3D model and for correcting the orientation of the site as regards the real-world space.</p>

scholarly journals Three-Dimensional Reconstruction of Structural Surface Model of Heritage Bridges Using UAV-Based Photogrammetric Point Clouds

2019 ◽  
Vol 11 (10) ◽  
pp. 1204 ◽  
Author(s):  
Yue Pan ◽  
Yiqing Dong ◽  
Dalei Wang ◽  
Airong Chen ◽  
Zhen Ye
Keyword(s):  
Classification Tree ◽  
Three Dimensional ◽  
Point Clouds ◽  
3D Models ◽  
Surface Model ◽  
Reconstruction Method ◽  
3D Point Clouds ◽  
Surface Models ◽  
Structural Surface ◽  
Better Than

Three-dimensional (3D) digital technology is essential to the maintenance and monitoring of cultural heritage sites. In the field of bridge engineering, 3D models generated from point clouds of existing bridges is drawing increasing attention. Currently, the widespread use of the unmanned aerial vehicle (UAV) provides a practical solution for generating 3D point clouds as well as models, which can drastically reduce the manual effort and cost involved. In this study, we present a semi-automated framework for generating structural surface models of heritage bridges. To be specific, we propose to tackle this challenge via a novel top-down method for segmenting main bridge components, combined with rule-based classification, to produce labeled 3D models from UAV photogrammetric point clouds. The point clouds of the heritage bridge are generated from the captured UAV images through the structure-from-motion workflow. A segmentation method is developed based on the supervoxel structure and global graph optimization, which can effectively separate bridge components based on geometric features. Then, recognition by the use of a classification tree and bridge geometry is utilized to recognize different structural elements from the obtained segments. Finally, surface modeling is conducted to generate surface models of the recognized elements. Experiments using two bridges in China demonstrate the potential of the presented structural model reconstruction method using UAV photogrammetry and point cloud processing in 3D digital documentation of heritage bridges. By using given markers, the reconstruction error of point clouds can be as small as 0.4%. Moreover, the precision and recall of segmentation results using testing date are better than 0.8, and a recognition accuracy better than 0.8 is achieved.

scholarly journals Digital Surface Model Interpolation Based on 3D Mesh Models

2018 ◽  
Vol 11 (1) ◽  
pp. 24 ◽  
Author(s):  
Soohyeon Kim ◽  
Sooahm Rhee ◽  
Taejung Kim
Keyword(s):  
Image Matching ◽  
3D Visualization ◽  
Interpolation Method ◽  
Stereo Image ◽  
Distribution Model ◽  
Surface Model ◽  
Digital Surface Model ◽  
3D Mesh ◽  
Stereo Image Matching ◽  
Mesh Models

A digital surface model (DSM) is an important geospatial infrastructure used in various fields. In this paper, we deal with how to improve the quality of DSMs generated from stereo image matching. During stereo image matching, there are outliers due to mismatches, and non-matching regions due to match failure. Such outliers and non-matching regions have to be corrected accurately and efficiently for high-quality DSM generation. This process has been performed by applying a local distribution model, such as inverse distance weight (IDW), or by forming a triangulated irregular network (TIN). However, if the area of non-matching regions is large, it is not trivial to interpolate elevation values using neighboring cells. In this study, we proposed a new DSM interpolation method using a 3D mesh model, which is more robust to outliers and large holes. We compared mesh-based DSM with IDW-based DSM and analyzed the characteristics of each. The accuracy of the mesh-based DSM was a 2.80 m root mean square error (RMSE), while that for the IDW-based DSM was 3.22 m. While the mesh-based DSM successfully removed empty grid cells and outliers, the IDW-based DSM had sharper object boundaries. Because of the nature of surface reconstruction, object boundaries appeared smoother on the mesh-based DSM. We further propose a method of integrating the two DSMs. The integrated DSM maintains the sharpness of object boundaries without significant accuracy degradation. The contribution of this paper is the use of 3D mesh models (which have mainly been used for 3D visualization) for efficient removal of outliers and non-matching regions without a priori knowledge of surface types.

Holocene dyke-induced surface deformation at Krafla (Iceland) revealed by UAV-based high resolution 3D models

2020 ◽  
Author(s):  
Alessandro Tibaldi ◽  
Elena Russo ◽  
Luca Fallati
Keyword(s):  
Field Survey ◽  
Surface Deformation ◽  
Structural Data ◽  
3D Models ◽  
Surface Model ◽  
Normal Faulting ◽  
Volcanic Zone ◽  
The North ◽  
Very High ◽  
Main Deformation

&lt;p&gt;We analysed at very high detail the surface deformation along a volcanotectonic structure in the Krafla Fissure Swarm, located in the North Iceland Rift. The structure affects the Pleistocene Hituholar volcano and 12 ka old lava flows. The work has been carried out through the Structure from Motion technique (SfM) applied to UAV surveys, integrated with a lithostratigraphic and structural field survey. The resulting Orthomosaic and Digital Surface Model (DSM) have a resolution of 2.6 and 10 cm, respectively. The zone of deformation is characterised by topographic bulging, parallel extension fractures, and narrow grabens with locally floor uplift, which can be explained as the effect of shallow propagation of a dyke northward from the Krafla magma chamber. In fact, the study area has been interested by northward dyke propagation from the central Krafla volcano during several rifting events, among which the recentmost occurred in 1975-1984 (Krafla fire). The analysis of the very wide area covered by our UAV surveys indicates that changes in the pattern of surface deformation occur in correspondence of contacts between deposits with different rheological properties: the transition from very stiff lavas to soft hyaloclastites produces a change from extension fracturing to normal faulting. Moreover, we detected a series of extension fractures with NE-SW strike and left-lateral slip component, and NNW-SSE strike and right-lateral component, which are rotated clockwise and anticlockwise respect to the main NNE-SSW graben trend, and extend outward to the sides of the main deformation zone up to 17 m. We interpret these structures as originated in front of the dyke tip during its propagation and being successively bypassed by the dyke advancement. In case of an active volcanic zone, the comprehension of the surface deformation and of the significance of strike-slip faulting occurrence can help to determine how and where magma is propagating. Thus, these evidences may help to decipher geophysical data and surface structural data during volcano monitoring.&lt;/p&gt;

scholarly journals Integrative Visualization of Temporally Varying Medical Image Patterns

2011 ◽  
Vol 8 (2) ◽  
pp. 75-84
Author(s):  
Jung Soh ◽  
Mei Xiao ◽  
Thao Do ◽  
Oscar Meruvia-Pastor ◽  
Christoph W. Sensen
Keyword(s):  
Spatial Data ◽  
Temporal Integration ◽  
Brain Mri ◽  
3D Models ◽  
Surface Model ◽  
Image Stack ◽  
Disease Patterns ◽  
3D Surface ◽  
Mri Scans ◽  
Multiple Sclerosis Patients

Summary We have developed a tool for the visualization of temporal changes of disease patterns, using stacks of medical images collected in time-series experiments. With this tool, users can generate 3D surface models representing disease patterns and observe changes over time in size, shape, and location of clinically significant image patterns. Statistical measurements of the volume of the observed disease patterns can be performed simultaneously. Spatial data integration occurs through the combination of 2D slices of an image stack into a 3D surface model. Temporal integration occurs through the sequential visualization of the 3D models from different time points. Visual integration enables the tool to show 2D images, 3D models and statistical data simultaneously. As an example, the tool has been used to visualize brain MRI scans of several multiple sclerosis patients. It has been developed in Java™, to ensure portability and platform independence, with a user-friendly interface and can be downloaded free of charge for academic users.

scholarly journals INLINING 3D RECONSTRUCTION, MULTI-SOURCE TEXTURE MAPPING AND SEMANTIC ANALYSIS USING OBLIQUE AERIAL IMAGERY

2016 ◽  
Vol XLI-B3 ◽  
pp. 605-612
Author(s):  
D. Frommholz ◽  
M. Linkiewicz ◽  
A. M. Poznanska
Keyword(s):  
Semantic Analysis ◽  
Texture Mapping ◽  
Point Clouds ◽  
3D Models ◽  
Geometric Constraints ◽  
Aerial Images ◽  
Surface Model ◽  
Ray Casting ◽  
Real World Data ◽  
Visible Image

This paper proposes an in-line method for the simplified reconstruction of city buildings from nadir and oblique aerial images that at the same time are being used for multi-source texture mapping with minimal resampling. Further, the resulting unrectified texture atlases are analyzed for fac¸ade elements like windows to be reintegrated into the original 3D models. Tests on real-world data of Heligoland/ Germany comprising more than 800 buildings exposed a median positional deviation of 0.31 m at the fac¸ades compared to the cadastral map, a correctness of 67% for the detected windows and good visual quality when being rendered with GPU-based perspective correction. As part of the process building reconstruction takes the oriented input images and transforms them into dense point clouds by semi-global matching (SGM). The point sets undergo local RANSAC-based regression and topology analysis to detect adjacent planar surfaces and determine their semantics. Based on this information the roof, wall and ground surfaces found get intersected and limited in their extension to form a closed 3D building hull. For texture mapping the hull polygons are projected into each possible input bitmap to find suitable color sources regarding the coverage and resolution. Occlusions are detected by ray-casting a full-scale digital surface model (DSM) of the scene and stored in pixel-precise visibility maps. These maps are used to derive overlap statistics and radiometric adjustment coefficients to be applied when the visible image parts for each building polygon are being copied into a compact texture atlas without resampling whenever possible. The atlas bitmap is passed to a commercial object-based image analysis (OBIA) tool running a custom rule set to identify windows on the contained fac¸ade patches. Following multi-resolution segmentation and classification based on brightness and contrast differences potential window objects are evaluated against geometric constraints and conditionally grown, fused and filtered morphologically. The output polygons are vectorized and reintegrated into the previously reconstructed buildings by sparsely ray-tracing their vertices. Finally the enhanced 3D models get stored as textured geometry for visualization and semantically annotated ”LOD-2.5” CityGML objects for GIS applications.

scholarly journals AUTOMATIC BUILDING EXTRACTION AND ROOF RECONSTRUCTION IN 3K IMAGERY BASED ON LINE SEGMENTS

2016 ◽  
Vol XLI-B3 ◽  
pp. 625-631
Author(s):  
A. Köhn ◽  
J. Tian ◽  
F. Kurz
Keyword(s):  
3D Models ◽  
Surface Model ◽  
Building Extraction ◽  
Line Segments ◽  
Roof Structure ◽  
Line Segment Detection ◽  
Fitting Algorithm ◽  
Morphological Filtering ◽  
Stereo Imagery ◽  
On Line

We propose an image processing workflow to extract rectangular building footprints using georeferenced stereo-imagery and a derivative digital surface model (DSM) product. The approach applies a line segment detection procedure to the imagery and subsequently verifies identified line segments individually to create a footprint on the basis of the DSM. The footprint is further optimized by morphological filtering. Towards the realization of 3D models, we decompose the produced footprint and generate a 3D point cloud from DSM height information. By utilizing the robust RANSAC plane fitting algorithm, the roof structure can be correctly reconstructed. In an experimental part, the proposed approach has been performed on 3K aerial imagery.

scholarly journals The Leiden-Turin Archaeological Expedition to Saqqara: Preliminary Results of the 2019 Fieldwork Season.

2018 ◽  
Vol 4 ◽  
Author(s):  
Paolo Del Vesco ◽  
Christian Greco ◽  
Daniel Soliman ◽  
Nico Staring ◽  
Lara Weiss ◽  
...  
Keyword(s):  
3D Models ◽  
Surface Model ◽  
Underground Structures ◽  
Content Type ◽  
The Public ◽  
The North ◽  
Digital Reconstruction ◽  
Excavation Work ◽  
Area North ◽  
Small Finds

In the 2019 season, the joint Leiden-Turin Expedition to Saqqara continued work in the area north of the tomb of Maya with the aim of lowering the terrain above the new tomb discovered during the 2018 season (V82.1) and to prepare the area for further exploration in 2020. Many layers of deposit situated immediately to the north of the new tomb were removed and – although they mostly originated from previous excavations in the 1980s and 1990s –  systematically investigated. Several dumps of organic material such as linen and wood as well as numerous small finds and relief fragments were identified and recorded. In addition, existing storage facilities on site were renovated and upgraded. In this process, part of the underground structures of the tombs of Horemheb and Meryneith were surveyed by the 3D Survey Group (Politecnico di Milano). Thanks to the cooperation with the same Milanese team, a new documentation method was tested during the ongoing excavation work. Within a 3D-model the different stages of excavation were recorded, allowing the digital reconstruction of the stratigraphy of the whole area and the documentation of all finds in their original contexts. A Digital Surface Model of the entire concession area was also produced, and 3D-models of some of the previously excavated monumental tombs were created. Lastly, since heavy rainfalls had damaged many of the earlier excavated monumental tombs open to the public, they were consolidated and where necessary rebuilt. ملخص في موسم 2019، واصلت البعثة ليدن-تورينو المشتركة عملها في سقارة في المنطقة شمال قبر مايا، بهدف إزالة الأتربة التي تراكمت فوق القبر الجديد الذي اكتُشِف خلال موسم 2018 (V82.1) وإعداد المنطقة لموسم التنقيب لعام 2020. تمت إزالة العديد من طبقات الأتربة التي تغطي المنطقة الشمالية من القبر الجديد، بالرغم من أن هذه الرواسب تراكمت في الغالب بموجب الحفريات السابقة في الثمانينيات والتسعينيات، فقد تمت دراستها بشكل منهجي. قامت البعثة بالتنقيب وبتسجيل العديد من المواد العضوية مثل الكتان والخشب و غيرها من الشظايا واكتشافات أخرى صغيرة. كما أنه تم الكشف وتسجيل مرافق التخزين الموجودة في الموقع. من خلال هذه العملية، قام فريق الباحثين من الفرع التقني لجامعة ميلانو بمسح جزء من الهياكل تحت الأرض لمقابر حورمحب و مرينيث باستخدام الماسح ثلاثي الأبعاد. بفضل تعاون هذا الفريق، تم أثناء أعمال التنقيب اختبار طريقة جديدة في التوثيق. استناداً على النموذج ثلاثي الأبعاد، تم تسجيل مراحل التنقيب المختلفة مما سمح بإعادة البناء الرقمي للمنطقة بأكملها وتوثيق جميع الاكتشافات في أماكنها الأصلية. تم تنفيذ نموذج رقمي لكامل سطح المنطقة بالإضافة إلى إنشاء نماذج ثلاثية الأبعاد لبعض المقابر الأثرية التي نُقّب عنها سابقاً. وأخيراً، بما أن الأمطار الغزيرة ألحقت الضرر بالعديد من المقابر الأثرية المكتشفة سابقاً والمفتوحة لزيارة الجمهور، فقد تم تدعيمها وإعادة بناء الأقسام الضرورية.

scholarly journals Urban Scene Vectorized Modeling Based on Contour Deformation

2020 ◽  
Vol 9 (3) ◽  
pp. 162
Author(s):  
Lingjie Zhu ◽  
Shuhan Shen ◽  
Xiang Gao ◽  
Zhanyi Hu
Keyword(s):  
Autonomous Driving ◽  
3D Models ◽  
Deformation Energy ◽  
Surface Model ◽  
Urban Scenes ◽  
The Public ◽  
The Arts ◽  
Building Models ◽  
Urban Scene ◽  
Contour Deformation

Modeling urban scenes automatically is an important problem for both GIS and nonGIS specialists with applications like urban planning, autonomous driving, and virtual reality. In this paper, we present a novel contour deformation approach to generate regularized and vectorized 3D building models from the orthophoto and digital surface model (DSM).The proposed method has four major stages: dominant directions extraction, find target align direction, contour deformation, and model generation. To begin with, we extract dominant directions for each building contour in the orthophoto. Then every edge of the contour is assigned with one of the dominant directions via a Markov random field (MRF). Taking the assigned direction as target, we define a deformation energy with the Advanced Most-Isometric ParameterizationS (AMIPS) to align the contour to the dominant directions. Finally, the aligned contour is simplified and extruded to 3D models. Through the alignment deformation, we are able to straighten the contour while keeping the sharp turning corners. Our contour deformation based urban modeling approach is accurate and robust comparing with the state-of-the-arts as shown in experiments on the public dataset.

scholarly journals From 2D Images to 3D Tangible Models: Autostereoscopic and Haptic Visualization of Martian Rocks in Virtual Environments

2007 ◽  
Vol 16 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Cagatay Basdogan
Keyword(s):  
3D Reconstruction ◽  
3D Models ◽  
Rock Surface ◽  
Surface Model ◽  
Stereo Images ◽  
Martian Surface ◽  
Reconstruction Process ◽  
Low Transmission ◽  
2D Images ◽  
Multimodal Visualization

A planetary rover acquires a large collection of images while exploring its surrounding environment. For example, 2D stereo images of the Martian surface captured by the lander and the Sojourner rover during the Mars Pathfinder mission in 1997 were transmitted to Earth for scientific analysis and navigation planning. Due to the limited memory and computational power of the Sojourner rover, most of the images were captured by the lander and then transmitted to Earth directly for processing. If these images were merged together at the rover site to reconstruct a 3D representation of the rover's environment using its on-board resources, more information could potentially be transmitted to Earth in a compact manner. However, construction of a 3D model from multiple views is a highly challenging task to accomplish even for the new generation rovers (Spirit and Opportunity) running on the Mars surface at the time this article was written. Moreover, low transmission rates and communication intervals between Earth and Mars make the transmission of any data more difficult. We propose a robust and computationally efficient method for progressive transmission of multi-resolution 3D models of Martian rocks and soil reconstructed from a series of stereo images. For visualization of these models on Earth, we have developed a new multimodal visualization setup that integrates vision and touch. Our scheme for 3D reconstruction of Martian rocks from 2D images for visualization on Earth involves four main steps: a) acquisition of scans: depth maps are generated from stereo images, b) integration of scans: the scans are correctly positioned and oriented with respect to each other and fused to construct a 3D volumetric representation of the rocks using an octree, c) transmission: the volumetric data is encoded and progressively transmitted to Earth, d) visualization: a surface model is reconstructed from the transmitted data on Earth and displayed to a user through a new autostereoscopic visualization table and a haptic device for providing touch feedback. To test the practical utility of our approach, we first captured a sequence of stereo images of a rock surface from various viewpoints in JPL MarsYard using a mobile cart and then performed a series of 3D reconstruction experiments. In this paper, we discuss the steps of our reconstruction process, our multimodal visualization system, and the tradeoffs that have to be made to transmit multiresolution 3D models to Earth in an efficient manner under the constraints of limited computational resources, low transmission rate, and communication interval between Earth and Mars.

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