Semi-automated methods for 3-D reconstruction of macromolecular complexes

1995 ◽  
Vol 53 ◽  
pp. 42-43
Author(s):  
B. Carragher ◽  
M. Whittaker
Keyword(s):  
Three Dimensional ◽  
Time Saving ◽  
Macromolecular Complexes ◽  
Symmetry Properties ◽  
Dimensional Reconstruction ◽  
Experienced Operator ◽  
Projection Images ◽  
The Individual ◽  
Natural Symmetry

Techniques for three-dimensional reconstruction of macromolecular complexes from electron micrographs have been successfully used for many years. These include methods which take advantage of the natural symmetry properties of the structure (for example helical or icosahedral) as well as those that use single axis or other tilting geometries to reconstruct from a set of projection images. These techniques have traditionally relied on a very experienced operator to manually perform the often numerous and time consuming steps required to obtain the final reconstruction. While the guidance and oversight of an experienced and critical operator will always be an essential component of these techniques, recent advances in computer technology, microprocessor controlled microscopes and the availability of high quality CCD cameras have provided the means to automate many of the individual steps.During the acquisition of data automation provides benefits not only in terms of convenience and time saving but also in circumstances where manual procedures limit the quality of the final reconstruction.

Imaging of platinum-shadowed macromolecular complexes in dark field

1984 ◽  
Vol 42 ◽  
pp. 146-147
Author(s):  
D.W. Andrews ◽  
F.P. Ottensmeyer
Keyword(s):  
Thin Film ◽  
Three Dimensional ◽  
Average Diameter ◽  
Dark Field ◽  
Bright Field ◽  
Field Mode ◽  
Macromolecular Complexes ◽  
Average Mass ◽  
Topological Features ◽  
Projection Images

Shadowing with heavy metals has been used for many years to enhance the topological features of biological macromolecular complexes. The three dimensional features present in directionaly shadowed specimens often simplifies interpretation of projection images provided by other techniques. One difficulty with the method is the relatively large amount of metal used to achieve sufficient contrast in bright field images. Thick shadow films are undesirable because they decrease resolution due to an increased tendency for microcrystalline aggregates to form, because decoration artefacts become more severe and increased cap thickness makes estimation of dimensions more uncertain.The large increase in contrast provided by the dark field mode of imaging allows the use of shadow replicas with a much lower average mass thickness. To form the images in Fig. 1, latex spheres of 0.087 μ average diameter were unidirectionally shadowed with platinum carbon (Pt-C) and a thin film of carbon was indirectly evaporated on the specimen as a support.

A modified discrete tomography for improving the reconstruction of unknown multi-gray-level material in the `missing wedge' situation

2018 ◽  
Vol 25 (6) ◽  
pp. 1847-1859 ◽  
Author(s):  
Jianhong Liu ◽  
Zhiting Liang ◽  
Yong Guan ◽  
Wenbin Wei ◽  
Haobo Bai ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Iteration Process ◽  
Reconstruction Technique ◽  
Morphological Operations ◽  
Algebraic Reconstruction Technique ◽  
Discrete Tomography ◽  
Boundary Extraction ◽  
X Ray ◽  
Dimensional Reconstruction

Full angular rotational projections cannot always be acquired in tomographic reconstructions because of the limited space in the experimental setup, leading to the `missing wedge' situation. In this paper, a recovering `missing wedge' discrete algebraic reconstruction technique algorithm (rmwDART) has been proposed to solve the `missing wedge' problem and improve the quality of the three-dimensional reconstruction without prior knowledge of the material component's number or the material's values. By using oversegmentation, boundary extraction and mathematical morphological operations, `missing wedge' artifact areas can be located. Then, in the iteration process, by updating the located areas and regions, high-quality reconstructions can be obtained from the simulations, and the reconstructed images based on the rmwDART algorithm can be obtained from soft X-ray nano-computed tomography experiments. The results showed that there is the potential for discrete tomography.

scholarly journals Prefabricated Patient-Matched Cranial Implants for Reconstruction of Large Skull Defects

2013 ◽  
Vol 5 ◽  
pp. JCNSD.S11106 ◽  
Author(s):  
Jarle Sundseth ◽  
Jon Berg-Johnsen
Keyword(s):  
Bone Cement ◽  
Three Dimensional ◽  
Deep Infection ◽  
Skull Defects ◽  
Cranial Defect ◽  
Custom Made ◽  
Dimensional Reconstruction ◽  
Cranial Implant ◽  
Cranial Implants ◽  
The Individual

Cranial defects can be caused by injury, infection, or tumor invasion. Large defects should be reconstructed to protect the brain and normalize the cerebral hemodynamics. The conventional method is to cover the defect with bone cement. Custom-made implants designed for the individual patient are now available. We report our experience with one such product in patients with large cranial defects (>7.6 cm in diameter). A CT scan with 2 mm slices and a three-dimensional reconstruction were obtained from the patient. This information was dispatched to the company and used as a template to form the implant. The cranial implant was received within four weeks. From 2005 to 2010, custom-made cranial implants were used in 13 patients with large cranial defects. In 10 of the 13 patients, secondary deep infection was the cause of the cranial defect. All the implants fitted well or very well to the defect. No infections were seen after implantation; however, one patient was reoperated on for an epidural hematoma. A custom-made cranial implant is considerably more expensive than an implant made of bone cement, but ensures that the defect is optimally covered. The use of custom-made implants is straightforward and timesaving, and they provide an excellent medical and cosmetic result.

scholarly journals RESEARCH ON THE FACTORS AFFECTING THE ACCURACY OF THREE-DIMENSIONAL RECONSTRUCTION MODEL OF ROTOR UAV ARCHAEOLOGICAL SITES

2019 ◽  
Vol XLII-4/W20 ◽  
pp. 111-118
Author(s):  
X. Zheng ◽  
Y. G. Hu
Keyword(s):  
New Technologies ◽  
Three Dimensional ◽  
Archaeological Sites ◽  
Three Dimensional Reconstruction ◽  
Factors Affecting ◽  
Dimensional Reconstruction ◽  
Archaeological Work ◽  
Heritage Protection ◽  
Cultural Relics

Abstract. The work of cultural heritage protection has risen to the national strategic level in China in recent years. More and more high and new technologies are applied in the fields of cultural relics and archaeology, heritage protection, etc., including the drone photography technology. Because the cultural protection industry has high requirements for the accuracy of reconstruction results, it puts forward higher requirements for the three-dimensional reconstruction of drones. In this paper, the factors affecting the reconstruction accuracy of the rotor unmanned opportunity are analyzed and summarized in the archaeological protection of cultural relics, and the technical integration of the oblique photography technology in archaeological work is carried out to improve the quality of modeling results.

scholarly journals Simulation of Multi-Camera Indoor and Outdoor 3D Scanner

2018 ◽  
Vol 2 (3) ◽  
pp. 33-41
Author(s):  
Keyword(s):  
Three Dimensional ◽  
System Structure ◽  
3D Scanner ◽  
Background Removal ◽  
Dimensional Reconstruction ◽  
Characteristic Points ◽  
Graphic Engine ◽  
The Impact ◽  
Indoor And Outdoor

Photogrammetry allows a three-dimensional reconstruction of the object based on its multiple photography’s. The quality of the reconstruction result depends mostly on the gloss, the diversity of the texture, the lighting conditions, the quality of the camera calibration and the shape of the object. The article presents the results of a simulation of a multi-camera reconstruction system, for the needs of designing indoor and outdoor 3D scanner. The 3D reconstruction system works by simultaneously taking photographs of cameras located around the object. The simulation was created to investigate the optimal distribution of cameras and projectors casting a pattern that increases the number of characteristic points on the surface of the object. The impact of background removal in images on the reconstruction result as well as the texture quality of the object depending on the resolution and distance of the cameras from the object were also investigated. The graphic engine used to create the simulation also allows testing of impact of various conditions. The presented results prove that the parameters of the system structure, such as the placement of cameras, projectors, the selection of patterns projected by the projectors are important and their values can be determined at the stage of system simulation. The acquired results are promising and will be further investigated.

scholarly journals Three-Dimensional Reconstruction of Mechanical Parts Based on Digital Holography

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yaohui Dai ◽  
Haiyu Wu ◽  
Gang Zhu ◽  
Yan Yang
Keyword(s):  
Digital Holography ◽  
Optimization Problems ◽  
Three Dimensional ◽  
3D Display ◽  
Mechanical Parts ◽  
First Order ◽  
Reconstruction Image ◽  
Dimensional Reconstruction ◽  
Order Image

In reconstruction of the off-axis digital hologram of diffuse reflection objects, the position of the positive first-order image cannot be accurately obtained because of the low quality of the reconstruction image. This paper focuses on the above problem and proposes a method for marking the first-order image of the 1-FFT surface based on the fast Fourier transform (1-FFT). The parameters of angle of illumination light were investigated, and the maximum relative measurement error is 5.6% by standard objects. The multiaperture stitching technique in cylindrical coordinates is applied to digital holography technology, and the particle swarm optimization algorithm is used to transform the nonlinear equations into optimization problems to solve the splicing parameters. Finally, the 3D display of a typical rotary three-dimensional mechanical part is successfully realized with holography stitching using the above method.

A Fast and Smooth Carving Algorithm for Online 3D Reconstruction

2013 ◽  
Vol 311 ◽  
pp. 153-157
Author(s):  
Xing Gao ◽  
Ning Yu ◽  
Ming Hong Liao
Keyword(s):  
3D Reconstruction ◽  
Three Dimensional ◽  
Three Dimensional Reconstruction ◽  
Heritage Preservation ◽  
Reconstruction Methods ◽  
Space Carving ◽  
Dimensional Reconstruction ◽  
Bio Engineering ◽  
Current Reconstruction

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.

scholarly journals Evaluation of the effect of filters on reconstructed image quality from cone beam CT system

2021 ◽  
Vol 11 (1) ◽  
pp. 35-47
Author(s):  
Ngoc Ha Bui ◽  
Tien Hung Bui ◽  
Thuy Duong Tran ◽  
Kim Tuan Tran ◽  
Ngoc Toan Tran
Keyword(s):  
Image Quality ◽  
Cone Beam Ct ◽  
Three Dimensional ◽  
Reconstruction Algorithm ◽  
Reconstructed Image ◽  
Cone Beam ◽  
Spatial Filters ◽  
Dimensional Reconstruction ◽  
Ct System

: 3D Filtered Back Projection (FBP) is a three-dimensional reconstruction algorithm usually used in Cone Beam Computed Tomography (CBCT) system. FBP is one of the most popular algorithms due to its reconstruction is fast while quality of the result is acceptable. It can also handle a more considerable amount of data with same computer performance with other algorithms. However, the quality of a reconstructed image by the FBP algorithm strongly depends on spatial filters and denoising filters applied to projections. In this paper an evaluation of the reconstructed image quality of the CBCT system by using different denoising filters and spatial filters to find out the best filters for the CBCT system is performed. The result shows that, there is a significantly decrease of the noise of projection with the combination of Median and Gaussian filters. The reconstructed image has high resolution with Cosine filter and becomes more sharpen with Hanning filter.

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