3D Modeling Techniques Research Articles

Exploring reliable photogrammetry techniques for 3D modeling in anatomical research and education.

In anatomical research and education, three-dimensional visualization of anatomical structures is crucial for understanding spatial relationships in diagnostics, surgical planning, and teaching. While computed tomography (CT) and magnetic resonance imaging (MRI) offer valuable insights, they are often expensive and require specialized resources. This study explores photogrammetry as an affordable and accessible approach for 3D modeling in anatomical contexts. Two photogrammetry methods were compared: conventional open-source software (Colmap) and Apple's RealityKit Object Capture. Human C3 vertebrae were imaged with a 24 MP camera, with and without a cross-polarization filter. Reconstruction times, vertex distances, surface area, and volume measurements were compared to CT scans. Results revealed that the Object Capture method surpassed the conventional approach in reconstruction speed and user-friendliness. Both methods exhibited similar vertex distance from reference mesh and volume measurements, although the conventional approach produced larger surface areas compared to CT-based models. Cross-polarization filters eliminated the need for pre-processing and improved outcomes in challenging lighting conditions. This study demonstrates that photogrammetry, especially Object Capture, as a reliable and time-efficient tool for 3D modeling in anatomical research and education. It offers accessible alternatives to traditional techniques with advantages in texture mapping. While further validation of various anatomical structures is required, the accessibility and cost-effectiveness of photogrammetry make it a valuable asset for the field. In summary, photogrammetry would have the potential to revolutionize anatomical research and education by providing cost-effective, accessible, and accurate 3D modeling. The study underscores the promise of advancing anatomical research and education through the integration of photogrammetry with ongoing improvements in user-friendliness and accessibility.

Experience of use of the individual cutting block «5 in 1» using total knee arthroplasty

BACKGROUND: Total knee arthroplasty is the most progressively developing direction in the modern orthopaedic world. With the new visualization technologies, a whole new field of computer-assisted orthopaedic surgery has emerged. Generally, three groups can be distinguished in computer-assisted orthopedic surgery. The 1st group the use of individual resection blocks, templates or guides remains the most relevant today. However, the use of currently existing individual resection blocks, according to the literature, has contradictory results.
 CLINICAL CASES DESCRIPTION: This work presents the author's developed technique of a new preoperative 3D modeling for total knee arthroplasty using individual resection blocks. The paper presents a clinical case demonstrating the effectiveness of the new technique.
 CONCLUSION: The strategy CT+MRI, in our opinion, is the optimal solution not only for competent preoperative planning of total knee arthroplasty, but also for designing individual resection blocks. Our individual resection blocks allowed us to improve the accuracy of total knee arthroplasty.

Digital Recording of Historical Defensive Structures in Mountainous Areas Using Drones: Considerations and Comparisons

Digital recording of historic buildings and sites in mountainous areas could be challenging. The paper considers and discusses the case of historical defensive structures in the Italian Alps, designed and built to be not accessible. Drone images and photogrammetric techniques for 3D modeling play a fundamental role in the digital documentation of fortified constructions with non-contact techniques. This manuscript describes the use of drones for reconstructing the external surfaces of some fortified structures using traditional photogrammetric/SfM solutions and novel methods based on NeRFs. The case of direct orientation based on PPK and traditional GCPs placed on the ground is also discussed, considering the difficulties in placing and measuring control points in such environments.

Marine mammal morphometrics: 3D modeling and estimation validation

Techniques of 3D modeling have earned increasing popularity in scientific studies as they offered unprecedented traits in representing objects. As with all mathematical models, the 3D model will be useful once its accuracy has been validated with direct measurements and the robustness of its predictive capability tested. Although measures of body mass and volume are essential to comprehend the life history of animals, such morphometrics, especially total volume, are challenging to obtain from marine mammals due to their elusive nature, aquatic lifestyle, and large size. In this study, accurate measurements of body volume were directly detected from fresh carcasses of eleven finless porpoises (Neophocaena asiaeorientalis sunameri) and used to validate 3D models recreated from the same animals using Blender 3D graphics. Published models using truncated cones or elliptical shapes, based on 3, 5, 8, or 19 measurements of girths or heights & widths along the body, were also applied to porpoises to verify their accuracy. The Blender-generated 3D model produced the most accurate estimates of body volume compared to conventional truncated models, with a mean error of only 2.5% to the direct volume measurements. When photogrammetric images are available, the model can predict the body volumes based on total length alone. Similar accuracy was possible with the elliptical model using 19 height & width measurements (5% increments in total length). However, significant (p < 0.001) inaccuracy resulted from truncated models with 3, 5, or 8 girth measurements and elliptical models with 3 or 5 height & width measurements, and the accuracy of these models also decreased significantly as the number of measurement sites was reduced. Moreover, Blender 3D models can be extrapolated to animals with images absent, and such predicted volumes were tested to be trustworthy (overall skill = 0.998, r = 0.998, p < 0.01). Therefore, we recommend that researchers use either digital 3D models or elliptical models with 5% increments sectioning the torso to obtain accurate estimates of the body volumes of free-ranging marine mammals.

Photo-Stacking Technique for Neuroanatomical High-Definition Photography and 3-Dimensional Modeling

Three-dimensional (3D) neuroanatomical knowledge is vital in neurosurgery. Technological advances improved 3D anatomical perception, but they are usually expensive and not widely available. The aim of the present study was to provide a detailed description of the photo-stacking technique for high-resolution neuroanatomical photography and 3D modeling. The photo-stacking technique was described in a step-by-step approach. The time for image acquisition, file conversion, processing, and final production was measured using 2 processing methods. The total number and file size of images are presented. Measures of central tendency and dispersion report the measured values. Ten models were used in both methods achieving 20 models with high-definition images. The mean number of acquired images was 40.6 (14-67), image acquisition time 51.50±18.8 s, file conversion time 250±134.6s, processing time 50.46±21.46s and 41.97±20.84s, and 3D reconstruction time was 4.29±0.74s and 3.89±0.60s for methods B and C, respectively. The mean file size of RAW files is 1010±452megabyte (MB) and 101.06±38.09MB for Joint Photographic Experts Group files after conversion. The mean size of the final image means size is 71.9±0.126MB, and the mean file size of the 3D model means is 37.4±0.516MB for both methods. The total equipment used was less expensive than other reported systems. The photo-stacking technique is a simple and inexpensive method to create 3D models and high-definition images that could prove valuable in neuroanatomy training.

Kursk Fortress: on the Question of the Boundaries and Appearance of the Znamensky Monastery

Relevance. This article is an attempt to compare the changes in the stone architectural ensemble of the Znamensky Monastery in the period from the second half of the XVII century to the beginning of the XIX century. This topic has been little studied, and therefore it is relevant and in demand.The purpose is to determine the boundaries and appearance of the Kursk Znamensky Monastery from the moment of its foundation until the beginning of the XIX century on the basis of available materials.Objectives: to compare the location of the monastery buildings with the modern urban relief and to establish the type of buildings.Methodology. The article is based on the principles of historicism, scientific objectivity and consistency, which are supplemented by the method of reconstruction, the comparative historical method. In the work, among other things, the technique of virtual 3d modeling is used.Results. By superimposing city plans of different times and modern satellite images, the possible location of the buildings of the Znamensky Monastery is determined, its appearance of buildings is described. It is established that the appearance of the "Kursk Kremlin" has been constantly changing during the time of its existence. Comparing the boundaries of the foundations and studying the principles of construction of similar structures with the preserved images of the monastery allowed us to recreate the boundaries and appearance of the Kursk shrine. Thanks to the 3d modeling technique, the architectural appearance of the ensemble of the Znamensky Monastery of the XVII – XVIII centuries has been recreated.Conclusion. The conducted research gave grounds to assert that the architectural Znamensky Monastery has been the "axis" of urban development since its foundation. Its appearance was, on the one hand, typical of the temples of medieval Russia, on the other, Kursk stood out from many other Russian cities.

Fabrication and Characterization Techniques of In Vitro 3D Tissue Models.

The culturing of cells in the laboratory under controlled conditions has always been crucial for the advancement of scientific research. Cell-based assays have played an important role in providing simple, fast, accurate, and cost-effective methods in drug discovery, disease modeling, and tissue engineering while mitigating reliance on cost-intensive and ethically challenging animal studies. The techniques involved in culturing cells are critical as results are based on cellular response to drugs, cellular cues, external stimuli, and human physiology. In order to establish in vitro cultures, cells are either isolated from normal or diseased tissue and allowed to grow in two or three dimensions. Two-dimensional (2D) cell culture methods involve the proliferation of cells on flat rigid surfaces resulting in a monolayer culture, while in three-dimensional (3D) cell cultures, the additional dimension provides a more accurate representation of the tissue milieu. In this review, we discuss the various methods involved in the development of 3D cell culture systems emphasizing the differences between 2D and 3D systems and methods involved in the recapitulation of the organ-specific 3D microenvironment. In addition, we discuss the latest developments in 3D tissue model fabrication techniques, microfluidics-based organ-on-a-chip, and imaging as a characterization technique for 3D tissue models.

APPLICATION LIDAR AND POINT CLOUDS FOR 3D MODELING OF MUSEUM OBJECT

A museum is an institution intended for the general public that collects, cares for, presents, and preserves the community's cultural heritage for study, research, and pleasure or entertainment. The museum is undoubtedly one of the educational places for the community because it has many historical objects. It provides an opportunity to make the museum a vital place to be developed in a virtual form, such as Augmented Reality or Virtual Reality. However, one problem in developing virtual media is the 3D modeling of objects for interior design in museums. LiDAR (Light Detection And Ranging) is a near real-time 3D positioning technology. A point cloud collects data points in a 3D coordinate system, generally defined by x, y, and z coordinates. Both of these technologies can be used to create 3D object models quickly. The final result of this research is applying LiDAR & point cloud as a 3D modeling technique and assessing the accuracy of using these techniques for 3D modeling of the museum object

Techniques of fast 3D modeling in the Autodesk Inventor program

Techniques of fast 3D modeling in the Autodesk Inventor program

ВЛИЯНИЕ ПОГРЕШНОСТЕЙ ИЗГОТОВЛЕНИЯ ДЕТАЛЕЙ НА ДИСБАЛАНСЫ РОТОРА ГАЗОТУРБИННОГО ДВИГАТЕЛЯ ПРИ ЕГО СБОРКЕ

Increased vibrations of a gas turbine engine reduce the reliability and overall service life of the engine. The main reason for the appearance of increased vibrations is the dynamic imbalance (dynamic imbalance) of one or more engine rotors. Dynamic un-balance in its turn is a cumulative manifestation of static and moment unbalance of the rotor. One of the reasons for the appearance of unacceptable values of rotor imbalances is the imperfection of the geometric pa-rameters of the parts, that is, the manufacturing errors of these parts. Despite the fact that at present there are strict requirements for the accuracy of manufacturing parts of a gas turbine engine, it is impossible to manufacture a part without errors. When joining several rotors, the summing errors in the manufacture of parts may lead to a shift in the center of mass of the rotors, as well as to a misalignment of their axes, which in turn leads to an increase in the imbalances of the assembled rotor. As a result of the vibration of the assembled engine significantly exceed the permissible. The problem of the influence of errors in the manufacture of parts on the unbalances of the gas turbine engine rotor during its assembly is analyzed. A review analysis of the methods for solving this problem, presented in modern scientific papers, is car-ried out. A technique for 3D modeling of the GTE rotor assembly is given, taking into account the beat vectors to predict the static and moment imbalances of the assembled rotor. Based on the simulation results, the displacements of the center of mass of the analyzed rotor and the distortions of its axis are calculated for different positions of the beat vectors. The conclusion is made about the expediency of applying the considered methodology in the design of modern gas turbine engine.

3D modeling in the planning of treatment of femoral tumors

Background. The outcome of surgical treatment of fe-moral tumors (FT) depends on the knowledge of the real picture of the extent of bone and soft tissue damage. The objective picture of the lesion can be significantly supplemented by virtual modeling in the framework of MRI, CT, and 3D modeling of the process, which is practically not studied in Ukraine. Real solid modeling of a skeletal segment with a tumor can produce the most optimal volume of resection and structure formation for stable fixation of bone fragments. The purpose of the work is to improve the technique of 3D modeling of hip tumors for preoperative planning of surgical intervention and the development of the most optimal design of the device. Materials and methods. The available literature data were analyzed; the radiographs, case histories of 15 patients with FT were studied. Good results of treatment of the last are possible at thorough preoperative planning. Results. We use technologies of 3D modeling and 3D printing of solid models of FT. This allows planning the line of the proposed bone resection, to properly form a graft from bioactive ceramics, tutoplast or own bones. 3D modeling helps to create the most optimal design of the device, which provides stable fixation of these grafts to the femoral fragments. The length of resection of the tumor segment with the tumor was calculated using multidetector compu-ted tomography (MDC) perfusion. This makes it possible to conduct preoperative training to establish the structures of the formed fixators on the segment of bone fragments — graft (BFG), to determine its bearing capacity. Based on planning and preoperative training, 5 ope-rations were performed on the hip. To stabilize the BFG segment, optimized constructions based on a DHS-type clamp, LCP-plates, or a clamp for low-contact multiplane osteosynthesis were used. Conclusions. Application of the technology of 3D modeling and 3D printing of solid models of specific SC and tumors allow planning the line of the proposed bone resection. Based on this, you can form the size of the graft, create a fixator structure that provides stability in the BFG. The preoperative training facilitates surgery. All this helps to choose the most optimal treatment tactics.

THE EFFECT OF 3D TECHNOLOGIES IN STEREOMETRY TRAINING

The software proposed in the report can be used as a technological tool in the teaching and learning of the discipline of stereometry. The aim is to improve the learning process by supporting the development of students’ creativity and spatial imagination, qualities needed in the study of spatial geometric bodies. A new boundary method is used in the generation of geometric objects. This new method uses elements of the Cavalieri Indivisible method and Isaac Newton's boundary method, thus achieving higher accuracy with respect to generated objects compared to 3D systems that use the rules of trigonometry in the construction of geometric bodies. This article performs a comparative analysis between a traditional and a new method for generating 3D geometric objects according to certain parameters and criteria. The new method involved in the analysis was proposed by the author of the report. While the traditional one is based on trigonometry. Two parameters were studied, one for accuracy in generating objects, and the second determining speed. In order to generate cylindrical bodies, are used the quadratic Bézier curve and the 3D modeling technique known as an extrusion, which transforms two-dimensional objects into three-dimensional ones.. One way to generate a prism and pyramid is by extruding polygons. This report presents a new way of constructing edged bodies. The considered technique for 3D modeling participates in the analysis of the studied methods.

МОДЕЛЮВАННЯ СПРЯЖЕНИХ КРИВОЛІНІЙНИХ ПОВЕРХОНЬ НА БАЗІ КІНЕМАТИЧНОГО ГВИНТА

Modeling of mating curved surfaces for practical use in the design of mechanical engineering products based on a parametric kinematic screw. In mechanical engineering, when modeling conjugate curved surfaces of kinematic pairs, trochoid graphs and electronic modeling installations were used, they had low accuracy and productivity. It is proposed to optimize the process of creating universal graphic tools, where there is, in fact, a graphic representation of the parameters of kinematic conjugate curved surfaces, a change in one of which leads to a change in others, opens up the possibility of obtaining the shapes of parts with predetermined parameters. It should include wishes to expand the capabilities of the propeller diagram [1], taking into account the real picture of the kinematics in the design, which, when the distance between the axes of the propellers changes, would give a real idea of the change in the geometry of the contact surface at each point of the instantaneous movement of the wheels. The kinematic screw has proven itself well for the formation of conjugate ruled surfaces [3], therefore, geometric 3d-modeling of the kinematic parametric screw diagram for the formation of conjugate curved surfaces has become an urgent problem. The technique of 3d-modeling of the kinematic screw diagram is based on the theorems of Professor A.M. Podkorytova [4]. Modeling of mating curved surfaces on the basis of a parametric kinematic screw means that from graphic constructions at any stage of design, you can easily go to the calculation by an analytical method, if you need to check or accurately determine the parameters. It will allow you to visually represent the process of obtaining conjugate curvilinear kinematic pairs, to analyze the influence of each parameter on the profile and its structural dimensions, you can identify errors in the profiling of conjugate curved surfaces where to avoid them, which is what this article is about.

Mastering 3D Modeling in Blender: From Novice to Pro

The open-source 3D modeling and animation software Blender has become a powerhouse for artists, designers, and hobbyists. Blender's capabilities and creative industry effects are summarized in this abstract. Due to its comprehensive features and unwavering community support, Blender has grown from a simple tool to an industry standard. This flexible instrument suits beginners and experts. Blender has an excellent user interface, several modeling and sculpting capabilities, a robust material and texture system, and powerful rendering engines like Cycles and Eevee. Open-source development keeps Blender available to anyone, making it a pioneer in democratizing 3D modeling and animation technologies. Blender is a creative movement that lets anyone with an idea realize their vision. Blender is our entry to 3D modeling and animation, novice or experienced. This study discusses the essential techniques of 3D modeling, shading, materials, rendering, textures in blender, rigging and animation, and physical simulation. The review presents a guide step-by-step, ensuring that develop a solid foundation in each aspect of Blender's powerful toolset.

Numerical Study of Seismic Vibrations of Closely Located Buried Large Structures

The paper presents an efficient numerical technique for 3D-modeling of seismic stability of large buried structures. This technique allows considering the subsoil-structure contact interaction, gravity field effects, the inhomogeneous structure of soil and the varieties location of the earthquake hypocenter. As part of this technique is substantiated sizing of the soil-structure computational domain and continuum model for hard and soft soil foundations describing. The numerical technique for determining the kinematic conditions at the lower boundary of the computational domain from the experimental accelerations at the soil surface is given, offered special non-reflecting waves boundary conditions. The methods described above and algorithms for seismic resistance solving have been implemented in certified software package “Dynamica-3”, parallelization of the algorithm has been held according to the spatial domain decomposition principle. The developed numerical technique allows correctly posing the problem of seismic vibrations of buried structure, reducing computing costs and increasing the efficiency of numerical studies of Earthquake Engineering. Through this, the multiple recalculation of the task with different action scenarios generated from experimental seismograms by probabilistic methods became technically possible. The results of these calculations allow reflecting the experience of many earthquakes, which increases reliability of the estimates. The paper presents the model calculations results of seismic stability of large-sized buried structure—the mutual vertical and horizontal displacement of soil and building walls—which can then be used to assess strength of adjacent underground pipelines. A number of numerical experiments on seismic vibrations of nearby large-sized structures have been carried out to assess the mutual influence of structures on their behavior in an earthquake. It is established that the influence of nearby large-sized objects on seismic vibrations of structures differs for different buildings.

3D Carto-Graphics – Principles, Methods and Examples for Interactive Atlases

Abstract. Atlases are designed to visualize, explore and analyze topographic and thematic information in a geographic environment. As 3D data and real-time display techniques are increasingly available, a trend towards 3D atlases can be observed like the newly released Earth 3D Amazing Atlas (2017) and the Atlas of Switzerland – online (2016). While creating such interactive 3D atlases, editors are often confronted with the question: How realistic should a cartographic 3D representation look like? Can we introduce some visualization guidelines or even rules to determine the „graphic style“ of cartographic 3D elements? 3D visualizations tend to let users ask for more and more details, leading to photorealistic representations. But photorealism is mostly not suited to pin point the characteristics of a theme; obviously, a creek or a trail would hardly be recognized in a forest area. As Goralski (2009, p.3) states: “3D maps are not meant to be realistic 3D representations of the real world. As in other map types, cartographic rules of abstraction, symbolization and generalization have to be used, to assure efficient transfer of the depicted geographical information, tailored to the purpose, and suitable for the target map user.”In our presentation, we will clarify the term of 3D carto-graphics, depict principles, and describe suitable methods and corresponding techniques. In the context of the national Atlas of Switzerland, we will apply and examine these design concepts for 3D representations within the 3D mapping space (Sieber et al. 2013).A carto-graphic style for 3D is based on 2D cartographic rules (Imhof 1965) and non-photorealistic computer graphics (Doellner 2012, Bodum 2005). Principles concerning 3D modeling are fundamental for the different representational aspects. In this context, we will discuss principles such as a degree of realism, the level of visual complexity of 3D maps, the graphic quality of map elements, the 3D visualization and symbolization (Near-Far/Distance-Density problem), etc. considering dynamic and real-time applications. As an example of a 3D principle, the visualization should always originate from 3D data; thus a 2D map is a special case of a 3D map (Sieber et al. 2012).Methods and techniques of 3D modeling affect the whole 3D scene consisting of terrain/topography, and different map objects. We will present some ideas and techniques how to treat 3D topography, and objects like point symbols, charts, lines, areas and solid objects considering real-time interaction. As an example of such methods recommended in the field of 3D topography, DTMs should be based on high-resolution and smoothed TINs applying techniques of low poly height fields (Ferguson 2013). Adaptive DTM smoothing using topographic position index (TPI) and filtering techniques are also taken into consideration (Guisan et al. 1999, Kettunen et al. 2017). For appropriate relief shading, an exemplary approach using smoothing and enhance techniques is suggested (Geisthövel 2017).To illustrate the described methods and techniques, we present and discuss characteristic examples from various application fields. Examples may come from cartography, computer graphics, and even from data journalism and info-graphics. In order to demonstrate the feasibility and the usability of this approach, we plan to implement a set of 3D visualizations, which can be interacted with in real-time by means of the Virtual Globe engine of the Atlas of Switzerland – online.

Integration of aerial oblique imagery and terrestrial imagery for optimized 3D modeling in urban areas

Photorealistic three-dimensional (3D) models are fundamental to the spatial data infrastructure of a digital city, and have numerous potential applications in areas such as urban planning, urban management, urban monitoring, and urban environmental studies. Recent developments in aerial oblique photogrammetry based on aircraft or unmanned aerial vehicles (UAVs) offer promising techniques for 3D modeling. However, 3D models generated from aerial oblique imagery in urban areas with densely distributed high-rise buildings may show geometric defects and blurred textures, especially on building façades, due to problems such as occlusion and large camera tilt angles. Meanwhile, mobile mapping systems (MMSs) can capture terrestrial images of close-range objects from a complementary view on the ground at a high level of detail, but do not offer full coverage. The integration of aerial oblique imagery with terrestrial imagery offers promising opportunities to optimize 3D modeling in urban areas. This paper presents a novel method of integrating these two image types through automatic feature matching and combined bundle adjustment between them, and based on the integrated results to optimize the geometry and texture of the 3D models generated from aerial oblique imagery. Experimental analyses were conducted on two datasets of aerial and terrestrial images collected in Dortmund, Germany and in Hong Kong. The results indicate that the proposed approach effectively integrates images from the two platforms and thereby improves 3D modeling in urban areas.

Quantitative 3D phase field modelling of solidification using next-generation adaptive mesh refinement

Phase field (PF) models are one of the most popular methods for simulating solidification microstructures due to their fundamental connections to the physics of phase transformations. However, these methods are numerically very stiff due to the multiple length scales in a solidifying material, from the nanoscopic solid-liquid interface, to dendritic structures on the order of hundreds of microns. While this problem can be greatly alleviated by thin-interface analytical treatments of the PF equations, additional numerical methods are required to explore experimentally relevant sample sizes and times scales. It was shown about 18years ago that the use of dynamic adaptive mesh refinement (AMR) can alleviate this problem by exploiting the simple fact that the majority of the solidification kinetics occur at the solid-liquid interface, which scales with a lower dimensionality than the embedding system itself. AMR methods, together with asymptotic analysis, nowadays provide one of the most efficient numerical strategies for self-consistent quantitative PF modelling of solidification microstructure processes. This paper highlights the latest developments in the AMR technique for 3D modelling of solidification using classical phase field equations. This includes a move away from finite element techniques to faster finite differencing through the use of dynamic mini-meshes which are each associated with each node of a 3D Octree data structure, and distributed MPI parallelism that uses a new communication algorithm to decompose a 3D domain into multiple adaptive meshes that are spawned on separate cores. The numerical technique is discussed, followed by demonstrations of the new AMR algorithm on select benchmark solidification problems, as well as some illustrations of multi-phase modelling using a recently developed multi-order parameter phase field model.

Archaeological Site Information Modelling and Management Based on Close-Range Photogrammetry and GIS

New challenges in management and restoration of archaeological sites require the utilization of advanced technologies and systems to assist in preserving the important legacy of human heritage. These challenges include monitoring and preserving of site landscapes, maintenance and rehabilitation of archaeological structures, and quality and safety management. In this research, an integrated methodology based on photogrammetry and Three-Dimensional (3D) Geographic Information System (GIS) is developed to capture and model essential details needed for the proper management of archaeological sites. Recent advances in digital imagery and modelling utilize photogrammetry as an efficient technique for 3D modelling of archaeological sites to derive accurate measurements of size, shape, position, and texture of objects using two-dimensional digital photographs. Spatial data that include aerial stereo photographs, satellite images, close-range photos, terrestrial surveying and Global Positioning Systems (GPS) are integrated within the design of the proposed model. The approach is validated with a case study of Ajloun Castle, one of the ancient and important preserved structures located in Jordan. Various sequential levels of details have been developed for the castle: Orthophoto, Digital Elevation Model (DEM), structures geometry and site layout and 3D textured model. The suggested methodology is expected to be efficient in modelling and documenting archaeological structures. The developed model is utilized to assess the management of archaeological structures through feasibility analysis, rehabilitation decisions, and safety planning.

Sketch-based 3D modeling by aligning outlines of an image

Abstract In this paper we present an efficient technique for sketch-based 3D modeling using automatically extracted image features. Creating a 3D model often requires a drawing of irregular shapes composed of curved lines as a starting point but it is difficult to hand-draw such lines without introducing awkward bumps and edges along the lines. We propose an automatic alignment of a user's hand-drawn sketch lines to the contour lines of an image, facilitating a considerable level of ease with which the user can carelessly continue sketching while the system intelligently snaps the sketch lines to a background image contour, no longer requiring the strenuous effort and stress of trying to make a perfect line during the modeling task. This interactive technique seamlessly combines the efficiency and perception of the human user with the accuracy of computational power, applied to the domain of 3D modeling where the utmost precision of on-screen drawing has been one of the hurdles of the task hitherto considered a job requiring a highly skilled and careful manipulation by the user. We provide several examples to demonstrate the accuracy and efficiency of the method with which complex shapes were achieved easily and quickly in the interactive outline drawing task. Highlights We present an efficient technique for sketch-based 3D modeling using automatically extracted image features. An automatic and real-time method is proposed to align a user's hand-drawn sketch line to the contour lines of an image, facilitating a considerable level of ease for 3D modeling. We use a geometric method to align a sketch line to the outlines of an image using the features of the sketch line and contour lines of an image, and some operations are proposed to refine the result of alignment. In the sketch-based 3D modeling method, the sketch line is represented by a editable spline, therefore, the aligned sketch line can be further adjusted interactively.