scholarly journals Enhancement of RGB-D Image Alignment Using Fiducial Markers

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1497 ◽  
Author(s):  
Tiago Madeira ◽  
Miguel Oliveira ◽  
Paulo Dias

Three-dimensional (3D) reconstruction methods generate a 3D textured model from the combination of data from several captures. As such, the geometrical transformations between these captures are required. The process of computing or refining these transformations is referred to as alignment. It is often a difficult problem to handle, in particular due to a lack of accuracy in the matching of features. We propose an optimization framework that takes advantage of fiducial markers placed in the scene. Since these markers are robustly detected, the problem of incorrect matching of features is overcome. The proposed procedure is capable of enhancing the 3D models created using consumer level RGB-D hand-held cameras, reducing visual artefacts caused by misalignments. One problem inherent to this solution is that the scene is polluted by the markers. Therefore, a tool was developed to allow their removal from the texture of the scene. Results show that our optimization framework is able to significantly reduce alignment errors between captures, which results in visually appealing reconstructions. Furthermore, the markers used to enhance the alignment are seamlessly removed from the final model texture.

Author(s):  
Jovana Radović

Within the last years terrestrial and airborne laser scanning has become a powerful technique for fast and efficient three-dimensional data acquisition of different kinds of objects. Airborne laser system (LiDAR) collects accurate georeferenced data of extremely large areas very quickly while the terrestrial laser scanner produces dense and geometrically accurate data. The combination of these two segments of laser scanning provides different areas of application. One of the applications is in the process of reconstruction of objects. Objects recorded with laser scanning technology and transferred into the final model represent the basis for building an object as it was original. In this paper, there will be shown two case studies based on usage of airborne and terrestrial laser scanning and processing of the data collected by them.


2017 ◽  
Vol 23 (1) ◽  
pp. 54-64 ◽  
Author(s):  
Xiaotong Jiang ◽  
Xiaosheng Cheng ◽  
Qingjin Peng ◽  
Luming Liang ◽  
Ning Dai ◽  
...  

Purpose It is a challenge to print a model with the size that is larger than the working volume of a three-dimensional (3D) printer. The purpose of this paper is to present a feasible approach to divide a large model into small printing parts to fit the volume of a printer and then assemble these parts into the final model. Design/methodology/approach The proposed approach is based on the skeletonization and the minima rule. The skeleton of a printing model is first extracted using the mesh contraction and the principal component analysis. The 3D model is then partitioned preliminarily into many smaller parts using the space sweep method and the minima rule. The preliminary partition is finally optimized using the greedy algorithm. Findings The skeleton of a 3D model can effectively represent a simplified version of the geometry of the 3D model. Using a model’s skeleton to partition the model is an efficient way. As it is generally desirable to have segmentations at concave creases and seams, the cutting position should be located in the concave region. The proposed approach can partition large models effectively to well retain the integrity of meaningful parts. Originality/value The proposed approach is new in the rapid prototyping field using the model skeletonization and the minima rule. Based on the authors’ knowledge, there is no method that concerns the integrity of meaningful parts for partitioning. The proposed method can achieve satisfactory results by the integrity of meaningful parts and assemblability for most 3D models.


Author(s):  
S. Hosseinian ◽  
H. Arefi

The 3D concept is extremely important in clinical studies of human body. Accurate 3D models of bony structures are currently required in clinical routine for diagnosis, patient follow-up, surgical planning, computer assisted surgery and biomechanical applications. However, 3D conventional medical imaging techniques such as computed tomography (CT) scan and magnetic resonance imaging (MRI) have serious limitations such as using in non-weight-bearing positions, costs and high radiation dose(for CT). Therefore, 3D reconstruction methods from biplanar X-ray images have been taken into consideration as reliable alternative methods in order to achieve accurate 3D models with low dose radiation in weight-bearing positions. Different methods have been offered for 3D reconstruction from X-ray images using photogrammetry which should be assessed. In this paper, after demonstrating the principles of 3D reconstruction from X-ray images, different existing methods of 3D reconstruction of bony structures from radiographs are classified and evaluated with various metrics and their advantages and disadvantages are mentioned. Finally, a comparison has been done on the presented methods with respect to several metrics such as accuracy, reconstruction time and their applications. With regards to the research, each method has several advantages and disadvantages which should be considered for a specific application.


2020 ◽  
Author(s):  
Javier Caviedes-Bucheli ◽  
Nestor Rios-Osorio ◽  
Diana Usme ◽  
Cristian Jimenez ◽  
Adriana Pinzon ◽  
...  

Abstract Background: The purpose of this study was to evaluate the changes in canal volume after root canal preparation in vivo with 3 different single-file techniques (Reciproc-Blue®, WaveOne-Gold® and XP-EndoShaper®), with a new method using CBCT and 3D reconstruction. Methods: In this prospective study, thirty human lower premolars from healthy patients were used, in which extraction was indicated for orthodontic reasons. All the teeth used were caries- and restoration-free with complete root development, without signs of periodontal disease or traumatic occlusion, and with only one straight canal (up to 25º curvature). Teeth were randomly divided into three different groups: Reciproc-Blue, WaveOne-Gold and XP-EndoShaper. CBCT scans before root canal preparation were used to create a 3D reconstruction with RHINOCEROS 5.0 software to assess the initial canal volume, and then compared with 3D reconstructions after canal preparation to measure the increase in canal volume. Student’s t test for paired data were used to determine statistically significant differences between the before and after canal volumes. Anova test was used to determine statistically significant differences in the percentage of canal volume increase between the groups and Tukey's post-hoc test were used to paired comparison.Results: Reciproc-Blue showed the higher increase in canal volume, followed by WaveOne-Gold and XP-EndoShaper (p = 0.003). XP-EndoShaper did not show a statistically significant increase in canal volume after root canal preparation (p = 0.06).Conclusion: With this model, Reciproc-Blue showed higher increase in root canal volume, followed by WaveOne-Gold, while XP-EndoShaper did not significantly increase root canal volume during preparation.


Author(s):  
L. Avanthey ◽  
L. Beaudoin ◽  
C. Villard ◽  
S. Mellouk ◽  
R. Treglia

Abstract. In this article, we study the interest of PiCam and its possibilities offered for the realization of a light payload (small and inexpensive) in order to perform the 3D reconstruction of dynamic scenes (underwater or aerial) in close-range remote sensing. We see that on these observation scales, movements of the scenes due to flora and fauna cannot be ignored if we want these objects to be part of the final model. We review the sensors used in the literature for 3D reconstruction and then present the arguments in favor of PiCam with regard to the constraints posed by the use of light and agile vectors. The main issue is the synchronization of these low cost sensors, which is not native: we explain the different steps to obtain a satisfactory synchronization rate with regard to the dynamism of the studied scenes and present the results obtained.


Author(s):  
A. Cardaci ◽  
A. Versaci ◽  
P. Azzola

Abstract. The creation of three-dimensional models for the cataloguing and documentation of cultural heritage is today an emerging need in the cultural sphere and, above all, for museums. The cultural heritage is still catalogued and documented based on descriptive files assorted of photographic images which, however, fail to outline its spatial richness, possible only through the use of 3D artefacts. The essay aims to propose a methodology of digitalization by low-cost and easy-to-use systems, to be employed even by non-expert survey and photogrammetry’s operators. The case study of the statue of San Nicola da Tolentino, preserved at the Sant’Agostino complex in Bergamo, offered the possibility of a comparison between 3D models acquired with different digitalization tools (professional/action/amateur cameras and smartphone) and processed by several image-based 3D Reconstruction software and methods.


Author(s):  
P. Hu ◽  
Z. Dong ◽  
P. Yuan ◽  
F. Liang ◽  
B. Yang

The three-dimensional (3D) reconstruction of urban buildings from point clouds has long been an active topic in applications related to human activities. However, due to the structures significantly differ in terms of complexity, the task of 3D reconstruction remains a challenging issue especially for the freeform surfaces. In this paper, we present a new reconstruction algorithm which allows the 3D-models of building as a combination of regular structures and irregular surfaces, where the regular structures are parameterized plane primitives and the irregular surfaces are expressed as meshes. The extraction of irregular surfaces starts with an over-segmented method for the unstructured point data, a region growing approach based the adjacent graph of super-voxels is then applied to collapse these super-voxels, and the freeform surfaces can be clustered from the voxels filtered by a thickness threshold. To achieve these regular planar primitives, the remaining voxels with a larger flatness will be further divided into multiscale super-voxels as basic units, and the final segmented planes are enriched and refined in a mutually reinforcing manner under the framework of a global energy optimization. We have implemented the proposed algorithms and mainly tested on two point clouds that differ in point density and urban characteristic, and experimental results on complex building structures illustrated the efficacy of the proposed framework.


Author(s):  
William D. A. Rickard ◽  
Jéssica Fernanda Ramos Coelho ◽  
Joshua Hollick ◽  
Susannah Soon ◽  
Andrew Woods

Photogrammetric three-dimensional (3D) reconstruction is an image processing technique used to develop digital 3D models from a series of two-dimensional images. This technique is commonly applied to optical photography though it can also be applied to microscopic imaging techniques such as scanning electron microscopy (SEM). The authors propose a method for the application of photogrammetry techniques to SEM micrographs in order to develop 3D models suitable for volumetric analysis. SEM operating parameters for image acquisition are explored and the relative effects discussed. This study considered a variety of microscopic samples, differing in size, geometry and composition, and found that optimal operating parameters vary with sample geometry. Evaluation of reconstructed 3D models suggests that the quality of the models strongly determines the accuracy of the volumetric measurements obtainable. In particular, they report on volumetric results achieved from a laser ablation pit and discuss considerations for data acquisition routines.


2013 ◽  
Vol 311 ◽  
pp. 153-157
Author(s):  
Xing Gao ◽  
Ning Yu ◽  
Ming Hong Liao

Online rapid three-dimensional reconstruction is widely applied in virtual reality, heritage preservation, bio-engineering and architectural fields. The error caused by image quality or manual import is the main reason for the low quality of model details when applying current reconstruction methods while meeting the time premise. To solve this problem, the paper proposes a fast and smooth carving algorithm for online 3d reconstruction by joining the filter. By applying the method, you can get a more realistic and smooth three-dimensional reconstruction results. First, we convert the input point cloud to meshes through Delaunay tetrahedralisation. Then we reconstruct the model with the space carving algorithm with the filter to obtain the result. The experiment result shows our method exceeds existing methods while meeting the time constraints under the premise at the same time.


2011 ◽  
Vol 96 (3) ◽  
pp. 274-280 ◽  
Author(s):  
Guang-Jiu Liu ◽  
Shao-Xiang Zhang ◽  
Ming-Guo Qiu ◽  
Li-Wen Tan ◽  
Qi-Yu Li ◽  
...  

Abstract Performing surgeries on the craniocervical junction presents a technical challenge for operating surgeons. Three-dimensional (3D) reconstruction and surgical simulation have improved the efficacy and success rate of surgeries. The aim of this study was to create a 3D, digitized visible model of the craniocervical junction region to help realize accurate simulation of craniocervical surgery on a graphic workstation. Transverse sectional anatomy data for the study were chosen from the first Chinese visible human. Manual axial segmentation of the skull base, cervical spine, cerebellum, vertebral artery, internal carotid artery, sigmoid sinus, internal jugular vein, brain stem, and spinal cord were carried out by using Photoshop software. The segmented structures were reconstructed in 3 dimensions with surface and volume rendering to accurately display 3D models spatially. In contrast to conventional 3D reconstruction techniques that are based on computed tomography and magnetic resonance imaging Digital Imaging and Communications in Medicine (DICOM) inputs and provide mostly osseous details, this technique can help to illustrate the surrounding soft tissue structure and provide a realistic surgical simulation. The reconstructed 3D model was successfully used in simulating complex procedures in the virtual environment, including the transoral approach, bone drillings, and clivus resection.


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