Volumetric Reconstruction Method Research Articles

Image response-assisted volumetric reconstruction for simultaneous multi-color light-field microscopy

Light-field microscopy enables real-time volumetric imaging, offering substantial advantages for real-time fluorescence imaging. However, when applied to multi-color imaging, positional cross-talk between different fluorescent signals in the object space reduces reconstruction accuracy. Additionally, imaging each color through sequential excitation of fluorophores significantly compromises imaging speed. In this paper, an image response-assisted volumetric reconstruction method that unmixes multi-color fluorescence light-field images using pixel support derived from the light-field imaging response is proposed. This approach enables simultaneous multi-color imaging with significantly improved volumetric reconstruction accuracy. The correctness and effectiveness of the proposed method are validated through both simulations and experiments. The root-mean-square-error of multi-color volumetric reconstruction is reduced by 37.87 % on average compared with the simultaneous multi-color reconstruction methods obtained by simply combining single-pixel spectrum conversion methods and linear unmixing method in rapid-moving micro-particle observation, showcasing high accuracy simultaneous multi-color imaging performance. Volumetric imaging of motor neurons and whole-body cells of live dual-color zebrafish larvae at 20 Hz demonstrates the ability to be applied to real biomedical imaging.

Towards Semantically-Consistent Deformable 2D-3D Registration for 3D Craniofacial Structure Estimation from A Single-View Lateral Cephalometric Radiograph.

The deep neural networks combined with the statistical shape model have enabled efficient deformable 2D-3D registration and recovery of 3D anatomical structures from a single radiograph. However, the recovered volumetric image tends to lack the volumetric fidelity of fine-grained anatomical structures and explicit consideration of cross-dimensional semantic correspondence. In this paper, we introduce a simple but effective solution for semantically-consistent deformable 2D-3D registration and detailed volumetric image recovery by inferring a voxel-wise registration field between the cone-beam computed tomography and a single lateral cephalometric radiograph (LC). The key idea is to refine the initial statistical model-based registration field with craniofacial structural details and semantic consistency from the LC. Specifically, our framework employs a self-supervised scheme to learn a voxel-level refiner of registration fields to provide fine-grained craniofacial structural details and volumetric fidelity. We also present a weakly supervised semantic consistency measure for semantic correspondence, relieving the requirements of volumetric image collections and annotations. Experiments showcase that our method achieves deformable 2D-3D registration with performance gains over state-of-the-art registration and radiograph-based volumetric reconstruction methods. The source code is available at https://github.com/Jyk-122/SC-DREG.

Establishing a new workflow in the study of core reduction intensity and distribution

New methodological approaches focused on studying the reduction and use-life of stone tools have emerged in recent years, enabling researchers to move beyond strict technical and technological characterizations and explore specific aspects of occupation dynamics and economic management of resources. Previous studies have shown the importance of reduction distributions of individual measurements rather than averaged values. In this sense, survival analysis, and more specifically Weibull distributions, are one of the main inferential tools used in reduction studies. However, the resolution of Weibull distribution obtained from different methods has not been tested experimentally. In this paper, we present an evaluation of some of the main methods used in the study of core reduction intensity, such as the Volumetric Reconstruction Method, the Scar Density Index, and the non-cortical surface percentage. Our results show 1) strong and positive correlations between these approaches and actual reduction intensity, 2) similar Weibull distributions for non-cortical surface percentage, Volumetric Reconstruction Method, and logarithmic transformation of Scar Density Index. In addition, 3) the results from each method show a similar intra-assemblage variation, with a high percentage of agreement between them. As a result, all the evaluated proposals are useful and reliable methods for estimating the degree of reduction. Finally, a workflow is proposed for approaching reduction in archaeological assemblages by integrating different methods in the same study.

Unravelling technological behaviors through core reduction intensity. The case of the early Protoaurignacian assemblage from Fumane Cave

This paper investigates core reduction intensity in the early Protoaurignacian lithic assemblage from Fumane Cave in northeastern Italy. Reduction intensity serves as a key tool to characterize blank selection strategies, raw material management, and the variability of knapping strategies throughout the reduction sequence by reconstructing the operatory field of core assemblages. Finally, it also aids in addressing the relationship between blades and bladelets, providing valuable insights into the behavioral and chrono-cultural significance of laminar productions within the Aurignacian technocomplex. To achieve these research goals, experimental work employing 3D scanning technology was conducted. This facilitated the comparison of different methods and variables for measuring reduction intensity, including the percentage of non-cortical surface, the Scar Density Index (SDI), and a novel adaptation of the Volumetric Reconstruction Method (VRM). Results demonstrate the effectiveness and potential of adapting the VRM for the study of reduction intensity in Upper Paleolithic laminar cores, and the provided R scripts and datasets will enable this method to be applied to other contexts with minimal need for modification to the workflow. Analysis of reduction intensity measures applied to the Protoaurignacian assemblage from Fumane Cave reveals slight variations based on factors such as the abundance and proximity of selected raw materials for blank production. Notably, the most prevalent raw material variety, the Maiolica, yields a higher number of less reduced cores, while reduction levels across all cores discarded at the site remain relatively high. The observed variability in the operatory field and the interrelation between blade and bladelet productions underscore the complexity and flexibility of Protoaurignacian behavior. This inherent complexity challenges any definitive separation between the operatory fields of blade and bladelet productions. These findings are particularly important to emphasize the importance of considering reduction intensity when examining technological variability and human behavior in Aurignacian studies. The proposed adaptation of the VRM and the effective combination with other measures of reduction, promises to allow future research to incorporate reduction intensity as a vital temporal component within studies on stone tool production. This integration offers a pathway to enhancing our understanding of the adaptive behaviors exhibited by Homo sapiens across diverse ecological settings and provides a clearer framework for better framing the development of the Upper Paleolithic.

Experimental Improvements to the Volume Ratio and Quantifying Movement Using Stone Artefact Analysis

Many conceptual frameworks of archaeological assemblages have assumed that stone artefact assemblages include all products of manufacture, use, and discard, although recent studies have indicated this is not always the case. The volume ratio is a method that examines the potential for the removal or addition of stone artefacts to an assemblage after manufacture. As humans transport material, and the movement of material effects the composition of assemblages, the alteration of an assemblage through the addition or removal of material can act as a proxy for mobility. This research uses three experimental assemblages to test the effect that different methods of volume quantification and reconstruction have on the calculation of the volume ratio. Results suggest observed assemblage volume is accurately and efficiently calculated using a standardised density of 2.46 g/cm³, while the modelled assemblage volume is relatively accurately calculated using either the Volumetric Reconstruction Method (VRM) or the Flake Volumetric Reconstruction Method (FVRM) with the potential for future research to further improve this methodology.

Dimensional X-Ray computed tomography: Apparent feature form error and its effect on measurement tasks

X-ray computed tomography (XCT) provides a unique set of dimensional measurement capabilities suitable for assessing complex geometry. However, due to the origins of XCT as a medical imaging method and qualitative non-destructive examination technique, only recently has XCT been rigorously investigated as a dimensional metrology tool. Although the data produced via XCT may be leveraged with conventional coordinate metrology techniques, the instrument physics and volumetric reconstruction methods which govern the accuracy and precision of the data are complex, workpiece-specific, and non-negligible. In particular, there is minimal prior work which has studied complex multi-step metrology tasks such as datum reference frame (DRF) construction and feature position measurement. In this work, a qualified artifact was used to evaluate the fitness of XCT for such a task. Multiple XCT systems were used, and multiple instrument magnification levels compared. The form error of planar and cylindrical features was evaluated. Further, the influence of individual feature reconstruction on the development of datums and upstream position measurements was studied. It was found that negative, i.e., bore-like, and positive, i.e., pin-like configurations of certain features were subject to distinct XCT artifact effects which caused upstream measurement errors when these features were used to construct a DRF. High magnification and X-ray scatter produced high spatial frequency noise in surface reconstruction while beam hardening and beam penetration distance variation produced gross apparent form error. The latter was associated with greater measurement errors in feature position measurement within an DRF.

The Technological Behaviours of Homo antecessor: Core Management and Reduction Intensity at Gran Dolina-TD6.2 (Atapuerca, Spain)

The ability of early hominins to overcome the constraints imposed by the characteristics of raw materials used for stone tool production is a key topic on the discussion about the evolution of hominin cognitive capabilities and technical behaviours. Thus, technological variability has been the centrepiece on this debate. However, the variability of lithic assemblages cannot be correctly interpreted without understanding site occupational models and function and considering that individual tools represent specific discard moments in a continuous reduction process. In Europe, the earliest technological record is represented by the scarce and scattered Mode 1 technologies, often deriving from occasional occupations or restricted activity areas yielding unrepresentative assemblages. In this paper, we approach the technological behaviours exhibited by Lower Palaeolithic hominins from the subunit TD6.2 of the Gran Dolina site (Atapuerca, Burgos) by including the perspective of reduction intensity studies on the analysis of technological variability. Gran Dolina TD6.2 is a unique and extremely significant archaeological context, as it represents the oldest multi-layered unit of domestic hominin occupations in the Early Pleistocene of Europe. We use the Volumetric Reconstruction Method (VRM) to estimate the original volume of the blanks and quantify the reduction intensity of each core individually to characterise the reduction distribution patterns using Weibull probability distribution functions. Our results suggest differential raw material management in terms of reduction intensity, according to the characteristics of each lithology. This could reflect a solid understanding of raw material qualities and a certain degree of planning. Altogether, the continuity between knapping strategies through reduction denotes constant adaptation to raw material constraints as well as particular knapping conditions, rather than specific compartmentalised mental schemes. In conclusion, Homo antecessor toolmakers would have been situational knappers whose technological behaviour would be highly adaptive. This research constitutes the first reduction approach for the European Early Pleistocene assemblages that will lead to a referential framework for other European Early Pleistocene sites.

Oldowan Technology Amid Shifting Environments ∼2.03–1.83 Million Years Ago

The Oldowan represents the earliest recurrent evidence of human material culture and one of the longest-lasting forms of technology. Its appearance across the African continent amid the Plio-Pleistocene profound ecological transformations, and posterior dispersal throughout the Old World is at the foundation of hominin technological dependence. However, uncertainties exist concerning the degree to which the Oldowan constitutes an environment-driven behavioral adaptation. Moreover, it is necessary to understand how Oldowan technology varied through time in response to hominin ecological demands. In this study, we present the stone tool assemblage from Ewass Oldupa, a recently discovered archeological site that signals the earliest hominin occupation of Oldupai Gorge (formerly Olduvai) ∼2.03 Ma. At Ewass Oldupa, hominins underwent marked environmental shifts over the course of a ∼200 kyr period. In this article, we deployed an analysis that combines technological and typological descriptions with an innovative quantitative approach, the Volumetric Reconstruction Method. Our results indicate that hominins overcame major ecological challenges while relying on technological strategies that remained essentially unchanged. This highlights the Oldowan efficiency, as its basic set of technological traits was able to sustain hominins throughout multiple environments.

A Comparison of Volumetric Reconstruction Methods of Archaeological Deposits Using Point-Cloud Data from Ahuahu, Aotearoa New Zealand

Collection of 3D data in archaeology is a long-standing practice. Traditionally, the focus of these data has been visualization as opposed to analysis. Three-dimensional data are often recorded during archaeological excavations, with the provenience of deposits, features, and artefacts documented by a variety of methods. Simple analysis of 3D data includes calculating the volumes of bound entities, such as deposits and features, and determining the spatial relationships of artifacts within these. The construction of these volumes presents challenges that originate in computer-aided design (CAD) but have implications for how data are used in archaeological analysis. We evaluate 3D construction processes using data from Waitetoke, Ahuahu Great Mercury Island, Aotearoa, New Zealand. Point clouds created with data collected by total station, photogrammetry, and terrestrial LiDAR using simultaneous localization and mapping (SLAM) are compared, as well as different methods for generating surface area and volumes with triangulated meshes and convex hulls. The differences between methods are evaluated and assessed in relation to analyzing artifact densities within deposits. While each method of 3D data acquisition and modeling has advantages in terms of accuracy and precision, other factors such as data collection and processing times must be considered when deciding on the most suitable.

Three-dimensional damage quantification of low velocity impact damage in thin composite plates using phased-array ultrasound

The evaluation of internal damage in multilayered composite materials is of great importance for high reliability-demanding applications, and remains a challenge due to the complex failure modes and mechanism of composite materials. This study presents a volumetric method of three-dimensional size quantification and prediction for low velocity impact damage in thin composite plates using phased-array ultrasound. A set of low velocity impact damages are induced in thin carbon fiber/epoxy resin matrix composite plates using quasi-static indentation tests. A volumetric reconstruction method is proposed to reconstruct a three-dimensional volume from the raw data, allowing for direct damage identification, localization, and quantification. Using the echo amplitude feature of the reconstructed volume, the 6 dB-drop method is employed to characterize the damage size in terms of volumes and areas. An impact size prediction model is established to correlate the impact energy and the damage volume/area. Comparisons are made between the microscopy measurement of the damage cross-section and results obtained using the developed method.

A new approach to measure reduction intensity on cores and tools on cobbles: the Volumetric Reconstruction Method

Knowing to what extent lithic cores have been reduced through knapping is an important step toward understanding the technological variability of lithic assemblages and disentangling the formation processes of archaeological sites. In addition, it is a good complement to more developed studies of reduction intensity in retouched tools and provides information on raw material management or site occupation dynamics. This paper presents a new methodology for estimating the intensity of reduction in cores and tools on cobbles, the Volumetric Reconstruction Method (VRM). It is based on a correction of the dimensions (length, width, and thickness) of each core from an assemblage. The median values of thickness and platform thickness of the assemblage’s flakes are used as corrections for the cores’ original dimensions, after its diacritic analysis. Then, based on these new dimensions, the volume or mass of the original blank are reconstructed using the ellipsoid volume formula. The accuracy of this method was experimentally tested, reproducing a variety of possible archaeological scenarios. The experimental results demonstrate a high inferential potential of the VRM, both in estimating the original volume or mass of the original blanks and in inferring the individual percentage of reduction for each core. The results of random resampling demonstrate the applicability of VRM to not size-biased archaeological contexts.

FusionMLS: Highly dynamic 3D reconstruction with consumer-grade RGB-D cameras

Multi-view dynamic three-dimensional reconstruction has typically required the use of custom shutter-synchronized camera rigs in order to capture scenes containing rapid movements or complex topology changes. In this paper, we demonstrate that multiple unsynchronized low-cost RGB-D cameras can be used for the same purpose. To alleviate issues caused by unsynchronized shutters, we propose a novel depth frame interpolation technique that allows synchronized data capture from highly dynamic 3D scenes. To manage the resulting huge number of input depth images, we also introduce an efficient moving least squares-based volumetric reconstruction method that generates triangle meshes of the scene. Our approach does not store the reconstruction volume in memory, making it memory-efficient and scalable to large scenes. Our implementation is completely GPU based and works in real time. The results shown herein, obtained with real data, demonstrate the effectiveness of our proposed method and its advantages compared to state-of-the-art approaches.

Volumetric 3D reconstruction of real objects using voxel mapping approach in a multiple-camera environment

Extracting 3D information from 2D images is an inverse estimation problem and a challenging task in itself. The aim of 2D to 3D reconstruction is to generate either a volume or a surface representing the object from multiple views. This paper presents a simple and accurate multiple-view volumetric 3D reconstruction method using an integrated approach based on homography estimation and voxel mapping. The homography-based approaches give accurate estimates but do not provide system dynamics. The voxel-based volumetric reconstruction methods provide system dynamics that are essential for system modeling. However, they face challenges while modeling the concavities. This paper presents a proposed 3D reconstruction method that combines homography estimation and the voxel mapping approach for improving the accuracy of 3D reconstruction. Experimental results show that the method efficiently reconstructs objects of known and unknown shape, fragile objects, and complex scenes with multiple objects. The use of homography along with voxel mapping in a multiple-camera environment brings out more details of the object for improving the quality of reconstruction.

Reconstruction of 3D lung models from 2D planning data sets for Hodgkin's lymphoma patients using combined deformable image registration and navigator channels

Late complications (cardiac toxicities, secondary lung, and breast cancer) remain a significant concern in the radiation treatment of Hodgkin's lymphoma (HL). To address this issue, predictive dose-risk models could potentially be used to estimate radiotherapy-related late toxicities. This study investigates the use of deformable image registration (DIR) and navigator channels (NCs) to reconstruct 3D lung models from 2D radiographic planning images, in order to retrospectively calculate the treatment dose exposure to HL patients treated with 2D planning, which are now experiencing late effects. Three-dimensional planning CT images of 52 current HL patients were acquired. 12 image sets were used to construct a male and a female population lung model. 23 "Reference" images were used to generate lung deformation adaptation templates, constructed by deforming the population model into each patient-specific lung geometry using a biomechanical-based DIR algorithm, MORFEUS. 17 "Test" patients were used to test the accuracy of the reconstruction technique by adapting existing templates using 2D digitally reconstructed radiographs. The adaptation process included three steps. First, a Reference patient was matched to a Test patient by thorax measurements. Second, four NCs (small regions of interest) were placed on the lung boundary to calculate 1D differences in lung edges. Third, the Reference lung model was adapted to the Test patient's lung using the 1D edge differences. The Reference-adapted Test model was then compared to the 3D lung contours of the actual Test patient by computing their percentage volume overlap (POL) and Dice coefficient. The average percentage overlapping volumes and Dice coefficient expressed as a percentage between the adapted and actual Test models were found to be 89.2 +/- 3.9% (Right lung = 88.8%; Left lung = 89.6%) and 89.3 +/- 2.7% (Right = 88.5%; Left = 90.2%), respectively. Paired T-tests demonstrated that the volumetric reconstruction method made a statistically significant improvement to the population lung model shape (p < 0.05). The error in the results were also comparable to the volume overlap difference observed between inhale and exhale lung volumes during free-breathing respiratory motion (POL: p = 0.43; Dice: p = 0.20), which implies that the accuracies of the reconstruction method are within breathing constraints and would not be the confining factor in estimating normal tissue dose exposure. The result findings show that the DIR-NC technique can achieve a high degree of reconstruction accuracy, and could be useful in approximating 3D dosimetric representations of historical 2D treatment. In turn, this could provide a better understanding of the biophysical relationship between dose-volume exposure and late term radiotherapy effects.

High‐Quality Volumetric Reconstruction on Optimal Lattices for Computed Tomography

AbstractWithin the context of emission tomography, we study volumetric reconstruction methods based on the Expectation Maximization (EM) algorithm. We show, for the first time, the equivalence of the standard implementation of the EM‐based reconstruction with an implementation based on hardware‐accelerated volume rendering for nearest‐neighbor (NN) interpolation. This equivalence suggests that higher‐order kernels should be used with caution and do not necessarily lead to better performance. We also show that the EM algorithm can easily be adapted for different lattices, the body‐centered cubic (BCC) one in particular. For validation purposes, we use the 3D version of the Shepp‐Logan synthetic phantom, for which we derive closed‐form analytical expressions of the projection data. The experimental results show the theoretically‐predicted optimality of NN interpolation in combination with the EM algorithm, for both the noiseless and the noisy case. Moreover, reconstruction on the BCC lattice leads to superior accuracy, more compact data representation, and better noise reduction compared to the Cartesian one. Finally, we show the usefulness of the proposed method for optical projection tomography of a mouse embryo.

Quantifying Uncertainties for Prostate Image-Guided Radiotherapy: A 3D Organ Reconstruction and Registration Method

The purpose of this paper is to present a method for volumetric reconstruction, registration and margin assigna- tion applicable to both conventional CT scans and on board CT imaging. This method does not depend on the shape of the organs, the bony anatomy or the use of markers, and we apply it to prostate and bladder. 3D reconstructions are performed by means of spline surfaces and the 3D reconstructed surfaces are registered to a planning surface, using a multidimen- sional alignment from the Euclidean distance transform and the Levenberg-Marquardt optimization algorithm. Once the reconstructed surfaces are registered, we define a mean surface and obtain the corresponding variances from this mean surface. The method works properly and demonstrates that once translations are insulated by registration, residual uncer- tainties can be handled with the margin assigned for delineation variation and organ deformation.

Percutaneous Vertebroplasty: Preliminary Experiences with Rotational Acquisitions and 3D Reconstructions for Therapy Control

Percutaneous vertebroplasty (PVP) is carried out under fluoroscopic control in most centers. The exclusion of implant leakage and the assessment of implant distribution might be difficult to assess based on two-dimensional radiographic projection images only. We evaluated the feasibility of performing a follow-up examination after PVP with rotational acquisitions and volumetric reconstructions in the angio suite. Twenty consecutive patients underwent standard PVP procedures under fluoroscopic control. Immediate postprocedure evaluation of the implant distribution in the angio suite (BV 3000; Philips, The Netherlands) was performed using rotational acquisitions (typical parameters for the image acquisition included a 17-cm field-of-view, 200 acquired images for a total angular range of 180 degrees ). Postprocessing of acquired volumetric datasets included multiplanar reconstruction (MPR), maximum intensity projection (MIP), and volume rendering technique (VRT) images that were displayed as two-dimensional slabs or as entire three-dimensional volumes. Image evaluation included lesion and implant assessment with special attention given to implant leakage. Findings from rotational acquisitions were compared to findings from postinterventional CT. The time to perform and to postprocess the rotational acquisitions was in all cases less then 10 min. Assessment of implant distribution after PVP using rotational image acquisition methods and volumetric reconstructions was possible in all patients. Cement distribution and potential leakage sites were visualized best on MIP images presented as slabs. From a total of 33 detected leakages with CT, 30 could be correctly detected by rotational image acquisition. Rotational image acquisitions and volumetric reconstruction methods provided a fast method to control radiographically the result of PVP in our cases.

Methods for Volumetric Reconstruction of Visual Scenes

In this paper, we present methods for 3D volumetric reconstruction of visual scenes photographed by multiple calibrated cameras placed at arbitrary viewpoints. Our goal is to generate a 3D model that can be rendered to synthesize new photo-realistic views of the scene. We improve upon existing voxel coloring/space carving approaches by introducing new ways to compute visibility and photo-consistency, as well as model infinitely large scenes. In particular, we describe a visibility approach that uses all possible color information from the photographs during reconstruction, photo-consistency measures that are more robust and/or require less manual intervention, and a volumetric warping method for application of these reconstruction methods to large-scale scenes.