Precise Surface Research Articles

Deep Semi-calibrated Near-field Photometric Stereo

Light calibration plays a crucial role in near-field photometric stereo for accurate surface normal estimation. It comprises light position calibration and light intensity calibration. In industrial applications, the light position calibration is typically performed once, as the facility remains fixed. However, the light intensity calibration needs to be repeated for real industrial scenes with variations in light intensity and fails for autoexposure industrial scenes. This study introduces a deep semi-calibrated near-field photometric stereo technique that achieves precise surface normal estimation without light intensity calibration. The technique consists of two parts: the near-field light intensity calibration network (NFLICN) and the near-field normal estimation network (NFNEN). NFLICN utilizes a point light model to self-calibrate pixel-wise light intensity. NFNEN, on the other hand, takes the calibrated light intensity as input and effectively utilizes local image features to estimate the surface normal. Experimental results on both synthetic testing datasets and the benchmark LUCES dataset confirm the state-of-the-art accuracy of our proposed method in surface normal estimation, even without light intensity calibration.

Physical-Vapor-Deposited Metal Oxide Thin Films for pH Sensing Applications: Last Decade of Research Progress.

In the last several decades, metal oxide thin films have attracted significant attention for the development of various existing and emerging technological applications, including pH sensors. The mandate for consistent and precise pH sensing techniques has been increasing across various fields, including environmental monitoring, biotechnology, food and agricultural industries, and medical diagnostics. Metal oxide thin films grown using physical vapor deposition (PVD) with precise control over film thickness, composition, and morphology are beneficial for pH sensing applications such as enhancing pH sensitivity and stability, quicker response, repeatability, and compatibility with miniaturization. Various PVD techniques, including sputtering, evaporation, and ion beam deposition, used to fabricate thin films for tailoring materials' properties for the advanced design and development of high-performing pH sensors, have been explored worldwide by many research groups. In addition, various thin film materials have also been investigated, including metal oxides, nitrides, and nanostructured films, to make very robust pH sensing electrodes with higher pH sensing performance. The development of novel materials and structures has enabled higher sensitivity, improved selectivity, and enhanced durability in harsh pH environments. The last decade has witnessed significant advancements in PVD thin films for pH sensing applications. The combination of precise film deposition techniques, novel materials, and surface functionalization strategies has led to improved pH sensing performance, making PVD thin films a promising choice for future pH sensing technologies.

Intensity response model and measurement error compensation method for chromatic confocal probe considering the incident angle

Chromatic confocal measurement technology is extensively applied in precision surface profiling within the industrial domain. However, due to limited measurement space and the complex shape of surfaces, it becomes challenging to ensure that the optical axis is aligned with the normal direction of the surface, particularly in regions with steep slopes. Although the reflected light can be captured when the probe is tilted within the numerical aperture angle, it introduces measurement uncertainty. In this paper, we investigate the reflective characteristics of incident light and develop a chromatic confocal light intensity response model that accounts for the incident angle. This model is based on the Rayleigh-Sommerfeld diffraction and dispersion theory. Simulation results demonstrate that the tilt angle results in a shift in the peak wavelength of the reflected spectrum. To compensate for the measurement error caused by this wavelength shift, we establish a calibration curve representing the angle and wavelength variation for the chromatic confocal measurement system. Experimental findings reveal that after compensation, the measurement error attributable to the incident angle is reduced by approximately 72 %.

Modification of Diamond Surface by Femtosecond Laser Pulses

The basic mechanisms of laser interaction with synthetic diamond are reviewed. The characteristics of the main regimes of diamond surface etching are considered. In addition to the well-known graphitization and ablation processes, nanoablation and accumulative graphitization, which have attracted relatively recent attention, are described in detail. The focus is on femtosecond (fs) laser exposure, which allows for the formation of a dense cold electron–hole plasma in the focal zone and minimal overheating in the surrounding area. This potentially opens the way to the development of unique laser-based technologies that combine physical and chemical processes for precise surface treatment and functionalization. The physical limitations that determine how precisely the diamond surface can be treated by short-pulsed laser radiation and possible ways to overcome them with the ultimate goal of removing ultrathin layers of the material are discussed. Special attention is paid to the novel possibility of inducing the local formation of point active defects—nitrogen vacancy (NV) complexes in the laser-irradiated zone. Such defects have been at the forefront of solid-state physics for the past thirty years due to continuous attempts to exploit their unique properties in quantum optics, quantum computing, magnetometry, probing, and other fields. Both regimes of NV center formation with and without graphitization of the diamond lattice are considered. Thus, it is shown that intense pulsed laser irradiation is a perfect tool for the processing of synthetic diamonds at the micro-, nano-, and even at the atomic level, which can be well controlled and managed.

Trueness and precision of combined healing abutment scan body system scans at different sites of maxilla after multiple repositioning of the scan body

ObjectivesTo evaluate the accuracy of the scans of the combined healing abutment-scan body (CHA-SB) system located at different sites of the maxilla when SBs are replaced in between each scan. MethodsThree SBs were seated into HAs located at the central incisor, first premolar, and first molar sites of a maxillary model inside a phantom head, and the model was scanned extraorally (CEREC Primescan SW 5.2). This procedure was repeated with new SBs until a total of 10 scans were performed. Standard tessellation language files of CHA-SBs at each implant location were isolated, transferred into analysis software (Geomagic Control X), and superimposed over the proprietary library files to analyze surface (root mean square), linear, and angular deviations. Trueness and precision were evaluated with one-way analysis of variance and Tukey tests. The correlation between surface and angular deviations was analyzed with Pearson's correlation (α=0.05). ResultsMolar implant scans had the highest surface and angular deviations (P≤.006), while central incisor implant scans had higher precision (surface deviations) than premolar implant scans (P=.041). Premolar implant scans had higher accuracy than central incisor implant scans on the y-axis (P≤.029). Central incisor implant scans had the highest accuracy on the z-axis (P≤.018). A strong positive correlation was observed between surface and angular deviations (r = 0.864, P<.001). ConclusionCentral incisor implant scans mostly had high accuracy and molar implant scans mostly had lower trueness. SBs were mostly positioned apically; however, the effect of SB replacement can be considered small as measured deviations were similar to those in previous studies and the precision of scans was high. Clinical SignificanceRepositioning of scan bodies into healing abutments would be expected to result in similar single crown positioning regardless of the location of the implant, considering high scan precision with the healing abutment-scan body system. The duration of the chairside adjustments of crowns in the posterior maxilla may be longer than those in the anterior region.

Trueness and precision of mandibular complete-arch implant scans when different data acquisition methods are used

ObjectivesTo evaluate the effect of different data acquisition methods on the trueness and precision of mandibular complete-arch implant scans. MethodsAn edentulous polyurethane master mandibular model with 6 implants was digitized by using an industrial-grade blue light scanner (ATOS Core 80 5MP) to obtain a master standard tessellation language (MSTL) file. The master model was also digitized by using either direct digital workflow with a stereoscopic camera (iCam 4D (IM)) or intraoral scanners (CEREC Primescan (PS) and Trios 4 (T4)) or indirect digital workflow with laboratory scanners (inEos X5 (X5) and CARES 7 (S7)) to obtain test-scan STLs (n = 10). All STL files were imported into a metrology-grade analysis software (Geomagic Control X 2020.1) and test-scan STLs were superimposed over MSTL. The root mean square method was used to calculate surface deviations, while angular deviations were also calculated. Kruskal–Wallis and Dunn's tests were used to evaluate measured deviations (surface and angular) for trueness and precision (α = 0.05). ResultsX5 and S7 had the lowest, and IM had the highest surface deviations (P ≤ .036). The angular deviations of PS were lower than those of X5, S7, and IM (P ≤ .008). When surface deviations were considered, T4 had the lowest precision among tested scanners (P ≤ .002), and the scans of IM had higher precision than those of PS (P = .003). Scanner type did not affect the precision of the scans when angular deviations were considered (P = .084). ConclusionsThe data acquisition method affected the trueness (surface and angular deviations) and precision (surface deviations) of mandibular complete-arch implant scans. Clinical significanceTested data acquisition methods may be feasible to digitize mandibular complete-arch implants considering the deviations of the scans, which were in the range of previously reported thresholds, and the high precision of scans. However, the frameworks fabricated with the direct digital workflow that involves the scans of the stereoscopic camera might require more adjustments than those fabricated by using the scans of other tested scanners.

Precision measurement of 5-DOF rotational error motion using two multi-probe error separation methods

This study proposes a new method for the precision measurement of the 5-DOF error motion of rotating machines. The developed seven-probe error separation system uses two measurement units, consisting of an upper four-probe unit and a lower three-probe unit, for the separation of error signals. From the seven probe output signals, the profile signals of the measured surface and the 5-DOF error motion signals, including random components, can be precisely separated. An analysis was carried out to examine the effects of the intersection term by the 5-DOF error motion signals, which is an additional measurement error cause. Furthermore, an effective calculation process capable of calculating a precise surface profile and error motion signal by compensating for the effect was proposed. Numerical validation tests and measurement experiments were performed. This showed it was possible to make accurate measurements by separating the 5-DOF error motions and surface profile signals and using a compensation calculation process. In addition, the effect of the stability error of the probe, which can be a significant factor in increasing measurement uncertainty, on the measurement results was observed and analyzed. Based on the geometric relationship of the measurement system, a process for estimating the expected effect of the stability error of the probe on the measurement result was presented. By applying this process, it is possible to determine the scale of probe stability error to secure the measurement reliability required when selecting a probe used in the system.

Investigating the effects of solution viscosity on the stability and success rate of SECCM imaging

Due to the capability of simultaneously detecting the morphology and electrochemical information of samples and limiting the electrochemical reaction to a range approximately the size of the inner diameter of the pipette tip opening, scanning electrochemical cell microscopy (SECCM) enables higher precision local electrochemical measurement and surface material delivery and has been demonstrating unique advantages and broad application prospects. However, the meniscus droplet at the pipette tip of SECCM is equivalent to the opening radius of the pipette tip, which is usually tens of nanometers to hundreds of nanometers. The tiny meniscus droplet makes it susceptible to evaporation and crystallization, which increases the likelihood of the pipette colliding with the sample during the scanning process, resulting in the failure of scanning. In this paper, the influence of solution viscosity on the shape variation of the droplet at the tip during the movement of the pipette of SECCM was studied by finite element analysis. It is proved that the increase of solution viscosity is helpful in reducing the shape variation of the droplet at the tip during the movement of the pipette. Then scanning experiments were carried out using a flat Au substrate and Au substrates with rounded triangle and rounded rectangular convex structures as the samples. According to the experimental results, increasing solution viscosity improves scanning success rates and scanning quality and effectively lowers the MSE of the scanning results. The experimental results also show that SECCM can image at a higher speed when the solution's viscosity increases since the deformation of the droplet at the tip is less than with a typical solution.

Investigation on the performance of wire electrical discharge machining (WEDM) using aluminium matrix composites (AMCs) micro-channel

This study focuses on microchannel fabrication of Al-10% SiC composite using Wire-EDM process with the applications of single variable and multi variable, optimization. This work was targeted keeping in considerations the wider scope of microchannel applications in the fields such as medical, aerospace, automobile, etc. In this research work, the experiment was conducted to achieve high precision and quality surface finish in terms of minimum surface roughness (SR), high material removal rate (MRR), low tool wear rate (TWR) and optimum spark gap (SG). The used experiments were design on the basis of Taguchi design of experiment approach. Four input process parameters were considered namely, pulse on time (Ton), sparking voltage (SV), wire tension (WT), and wire feed rate (WFR). For the experimentation task, the workpeice (Aluminum and silicon carbide (10% Wt SiCmicro)) material, in a desired shape was fabricated through stir casting process. The tool electrode applied for the experiment purpose had specification as, 0.25 mm diameter brass alloy wire (copper 63 percent and zinc 37 percent). For single variable optimization ANOVA (analysis of variance) was applied while as, for multi variables optimization, grey relational analysis (GRA) was applied. The results of the study indicated that, on the basis of single variable optimization, the highest contribution of Ton resulted in case of the performance measures, MRR and SR while as, for TWR and SG, the highest contribution of sparking voltage, observed. Furthermore, the findings of the study indicated that, on the basis of multi variables optimization, the optimal combination of input process parameters is, pulse on time 125 μs, sparking voltage 10 volt, wire tension 12 kgf, and wire feed rate 4 m min−1. These results also get support from the previous research works. The findings of this study be useful for microchannel manufacturing and other related industrial applications.

Rail Corrugation Index Development by Sound-Field Excitation on the Carriage Floor of In-Service Train.

The steel rail and wheel in the railway system offer a high precision and smooth-running surface. Nevertheless, the point of contact between the rail and wheel presents a critical area that can give rise to rail corrugation. This phenomenon can potentially elevate sound and vibration levels in the vicinity considerably, necessitating advanced monitoring and assessment measures. Recently, many efforts have been directed towards utilizing in-service trains for evaluating rail corrugation, and the evaluation has primarily relied on axle-box acceleration (ABA). However, the ABA measurements require a higher threshold for vibration detection. This study introduces a novel approach to rail corrugation detection by carriage floor acceleration (CFA), aimed at lowering the detection threshold. The method capitalizes on the acceleration data sensed on the carriage floor, which is induced by the sound pressure (e.g., sound-field excitation) generated at the wheel-rail contact point. An exploration of the correlation between these datasets is undertaken by simultaneously measuring both ABA and CFA. Moreover, a pivotal aspect of this research is the development of the eigenfrequency rail corrugation index (E-RCI), a mechanism that culminates energy around specific eigenfrequencies by CFA. Through this index, a focused analysis of rail corrugation patterns is facilitated. The study further delves into the stability, repeatability, and sensitivity of the E-RCI via varied measurement scenarios. Ultimately, the CFA-based rail corrugation identification is verified, establishing its practical applicability and offering a distinct approach to detecting and characterizing rail corrugation phenomena. This study has introduced an innovative methodology for rail corrugation detection using CFA, with the principal objective of lowering the detection threshold. This approach offers an efficient measurement technique for identifying rail corrugation areas, thereby potentially reducing maintenance costs and enhancing efficiency within the railway industry.

Emerging Atomic Layer Deposition Technology toward High‐k Gate Dielectrics, Energy, and Photocatalysis Applications

The precise design and efficient development of nanoscale materials at the atomic level has enabled high‐end renewable energy storage, conversion devices, and large‐scale environmental governance equipment. Atomic layer deposition (ALD) is a new vapor‐phase technology for precise surface thin‐film preparation, and is outstanding with self‐limiting reactions, large deposition area, adjustable film composition, film uniformity, angstrom thickness control, and low temperature. With these characteristics, ALD plays an important role in many industry and research fields. This review briefly introduces the principle, main technical advantages, and applications of ALD, including high‐k gate dielectrics, solar cells, fuel cells, and photocatalysis. The progress of the ALD technology in preparation and application of photocatalyst is emphatically reviewed, and the large‐scale application of ALD in photocatalytic thin‐film materials is prospected.

Surface Electric Potential Measurement with a Static Probe

Surface electric potential measurements are widely used in non-destructive inspection and testing of precision surfaces, for example, in the production of semiconductor devices and integrated circuits. Features of the construction and application of devices for measuring the surface electric potential using an immovable reference electrode are considered. Despite the need to increase the area of the probe compared to devices with a vibrating probe, measurement techniques with an immovable probe have a number of advantages and could expand the scope of surface electric potential measurements in the inspection of samples with precise surfaces. Models of the formation of a measuring signal in the presence of a spatial inhomogeneity of surface electric potential are presented and discussed.

Influence of silane interfacial chemistry on the curing process of anionic Polyamide 6 in glass reinforced composites

The manufacturing of composites based on reactive thermoplastic polyamide 6 (PA6), reinforced with glass particles or fibers for structural applications, is quite sensitive to the state of the interface. Surface hydroxyls present at the glass surface can completely inhibit both the PA6 polymerization and crystallization processes. Care must then be exerted when tuning the interfacial chemistry in this system. This work demonstrates how an adequate choice of silane coupling agent, combined with a precise surface grafting methodology and tight control of hydroxyl groups density on glass particulates, yields kinetics and degrees of polymerization and crystallization comparable to the pure PA6 resin. Various silanes were grafted onto the microparticles and their surfaces were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, confocal laser scanning microscopy and contact angle measurements. The activator was also grafted onto the glass surface to initiate polymerization directly from the surface. The results showed that all treated glass particles surfaces allowed obtaining a high degree of conversion but with varying polymerization and crystallization kinetics. The results provide fundamental information on the role of the surface chemistry of glass reinforcements on the polymerization and crystallization of PA6, which are essential for the proper control of composite manufacturing.

Rapid Fabrication of High-Performance Flexible Pressure Sensors Using Laser Pyrolysis Direct Writing.

The fabrication of flexible pressure sensors with low cost, high scalability, and easy fabrication is an essential driving force in developing flexible electronics, especially for high-performance sensors that require precise surface microstructures. However, optimizing complex fabrication processes and expensive microfabrication methods remains a significant challenge. In this study, we introduce a laser pyrolysis direct writing technology that enables rapid and efficient fabrication of high-performance flexible pressure sensors with a micro-truncated pyramid array. The pressure sensor demonstrates exceptional sensitivities, with the values of 3132.0, 322.5, and 27.8 kPa-1 in the pressure ranges of 0-0.5, 0.5-3.5, and 3.5-10 kPa, respectively. Furthermore, the sensor exhibits rapid response times (loading: 22 ms, unloading: 18 ms) and exceptional reliability, enduring over 3000 pressure loading and unloading cycles. Moreover, the pressure sensor can be easily integrated into a sensor array for spatial pressure distribution detection. The laser pyrolysis direct writing technology introduced in this study presents a highly efficient and promising approach to designing and fabricating high-performance flexible pressure sensors utilizing micro-structured polymer substrates.

An electrochemical biosensor based on graphene oxide for determination of sertraline hydrochloride as an antidepressant drug

This research was done to develop an electrochemical sensor for the determination of the antidepressant drug sertraline hydrochloride (SH) using carboxylated graphene oxide-modified glassy carbon electrodes and silver vanadate nanoparticles (AgVO3/c-GO/GCE). The modified electrode, made of AgVO3/c-GO nanocomposite, was prepared using a hydrothermal technique. Studying the morphology and structure of changed electrodes revealed that AgVO3 nanowires and c-GO nanosheets formed a 3D hybrid matrix with a significant precise surface area and increased porosity. The prepared AgVO3/c-GO/GCE can be anticipated to be an appropriate platform for selective and sensitive SH sensing, according to studies of the electrochemical properties using CV and DPV techniques. With a detection limit and sensitivity of 25 ± 0.5 nM and 0.01901 μA/μM, respectively, the suggested sensor demonstrated a broad linear response range from concentrations of 0 to 1600 μM. Finally, the design sensor's suitability for accurately and precisely determining the SH in pharmaceutical tablets was assessed.

A Review on Residual Stress in Metal Additive Manufacturing.

A new method for producing parts in the expanding sector is additive manufacturing. The appropriate name for three-dimensional (3D) printing is additive manufacturing because it produces the part layer by layer. Plastics and metals can be 3D printed in large quantities with the precise surface finish and feature quality needed in additive manufacturing. More specifically, direct metal sintering, direct energy deposition, and metal binder jetting are used in 3D printing. The computer-aided design model is completed when the powder bed has been successively scanned and lowered. The metal sintering process uses a powder bed with powder metal, and laser selectively melts a flattened bed of powder, which is done with roller with successive rolling of new layer on previous into desired shape before a new layer is pushed on top of the previous layer. As a result, the new layer has solidified on top of the earlier layer, causing the prior layer to melt back again. Because of the unique thermal cycle, this results in residual stress (RS). The unique thermal cycle of metal additive manufacturing is characterized by (1) rapid heating rate caused by high energy intensity and steep temperature gradients; (2) rapid solidification with high cooling rates because of the small volume of melt pool; and (3) melt back, which involves simultaneous melting of the top powder layer and re-melting of underlying previously solidified layers. The presence of RS in metal additive manufacturing (AM) creates difficulties that restrict the process's ability to produce parts at an industrial scale. During and after manufacturing, these forces may cause parts to distort and crack. This can be solved by heating the powder bed, which will lessen this type of issue. The causes, traits, and reduction of RS are the main topics of this review article. A number of conceptual approaches to reducing RS are addressed to provide some useful inspiration for creating a methodical RS balancing procedure for AM. These approaches are based on the state and future of the relevant techniques.

Markedly Improved Catalytic Dehydration of Sorbitol to Isosorbide by Sol-Gel Sulfated Zirconia: A Quantitative Structure-Reactivity Study.

Isosorbide, a bicyclic C6 diol, has considerable value as a precursor for the production of bio-derived polymers. Current production of isosorbide from sorbitol utilizes homogeneous acid, commonly H2SO4, creating harmful waste and complicating separation. Thus, a heterogeneous acid catalyst capable of producing isosorbide from sorbitol in high yield under mild conditions would be desirable. Reported here is a quantitative investigation of the liquid-phase dehydration of neat sorbitol over sulfated zirconia (SZ) solid acid catalysts produced via sol-gel synthesis. The catalyst preparation allows for precise surface area control (morphology) and tunable catalytic activity. The S/Zr ratio (0.1-2.0) and calcination temperature (425-625 °C) were varied to evaluate their effects on morphology, acidity, and reaction kinetics and, as a result, to optimize the catalytic system for this transformation. With the optimal SZ catalyst, complete conversion of sorbitol occurred in <2 h under mild conditions to give isosorbide in 76% yield. Overall, the quantitative kinetics and structure-reactivity studies provided valuable insights into the parameters that govern product yields and SZ catalyst activity, central among these being the relative proportion of acid site types and Brønsted surface density.

Improvement of electrical insulating properties for defective metal/epoxy resin interface in power modules by micro-plasma jet

High-voltage power modules inevitably face the critical problem of electric field distortion at triple-junction point (Cu/insulation substrate/potting material) and accidental introduction of unexpected micro-metal defects on insulation substrate, which damages electrical insulating properties and induces breakdown. In this study, a novel precise surface treatment method based on atmospheric pressure micro-plasma jet (μ-APPJ) is proposed for rejuvenating and improving electrical insulating properties of defective Cu/epoxy resin (EP) substrate in power modules. Results show that a typical μ-APPJ with a diameter of about 200 μm is developed to precisely treat the micro-level metal defect in Cu/EP interface, and a spherical-clustered Si-containing functional film (∼Si-O4) can be fabricated on EP substrate by optimized Ar/Hexamethyldisiloxane (HMDSO)/μ-APPJ, which significantly enhances the hydrophobicity of EP surface. Moreover, the plasma-assisted film deposition around μm-defect improves interface electrical properties of defective Cu/EP samples, evidenced by higher flashover voltages and suppressed partial discharge. Further analysis based on simulations reveals that the deposited typical film not only promotes charge mobility and creepage distance on EP, but also introduces additional trap levels that capture electrons and inhibit electric field around metal defects, thereby suppressing partial discharge failure and improving electrical insulating properties.

The relationship of diabetic retinopathy severity scales with frequency and surface area of diabetic retinopathy lesions

PurposeTo assess the relationship between qualitative diabetic retinopathy (DR) scales with the precise numbers and surface area of DR lesions within the Early Treatment Diabetic Retinopathy Study (ETDRS) standard seven field (S7F) region on ultrawide-field (UWF) color fundus images.MethodsIn this study, we collected UWF images from adult patients with diabetes. Poor-quality images and eyes with any pathology precluding assessment of DR severity were excluded. The DR lesions were manually segmented. DR severity was graded according to the International Clinical Diabetic Retinopathy (ICDR) and AA protocol by two masked graders within the ETDRS S7F. These lesions’ numbers and surface area were computed and correlated against the DR scores using the Kruskal–Wallis H test. Cohen’s Kappa was performed to determine the agreement between two graders.ResultsOne thousand five hundred and twenty eyes of 869 patients (294 females, 756 right eyes) with a mean age of 58.7 years were included. 47.4% were graded as no DR, 2.2% as mild non-proliferative DR (NPDR), 24.0% as moderate NPDR, 6.3% as severe NPDR, and 20.1% as proliferative DR (PDR). The area and number of DR lesions generally increased as the ICDR level increased up to severe NPDR, but decreased from severe NPDR to PDR. There was perfect intergrader agreement on the DR severity.ConclusionA quantitative approach reveals that DR lesions’ number and area generally correlate with ICDR-based categorical DR severity levels with an increasing trend in the number and area of DR lesions from mild to severe NPDR and a decrease from severe NPDR to PDR.

Soft tissue monitoring of the surgical field: detection and tracking of breast surface deformations.

Deformable object tracking is common in the computer vision field, with applications typically focusing on nonrigid shape detection and usually not requiring specific 3D point localization.In surgical guidance however, accurate navigation is intrinsically linked to precise correspondence of tissue structure. This work presents a contactless, automated fiducial acquisition method using stereo video of the operating field to provide reliable fiducial localization for an image guidance framework in breast conserving surgery. On n=8 breasts from healthy volunteers, the breast surface was measured throughout the full range of arm motion in a supine mock-surgical position. Using hand-drawn inked fiducials, adaptive thresholding, and KAZE feature matching, precise three-dimensional fiducial locations were detected and tracked through tool interference, partial and complete marker occlusions, significant displacements and nonrigid shape distortions. Compared to digitization with a conventional optically tracked stylus, fiducials were automatically localized with 1.6 ± 0.5 mm accuracy and the two measurement methods did not significantly differ. The algorithm provided an average false discovery rate <0.1% with all cases' rates below 0.2%. On average, 85.6 ± 5.9% of visible fiducials were automatically detected and tracked, and 99.1 ± 1.1% of frames provided only true positive fiducial measurements, which indicates the algorithm achieves a data stream that can be used for reliable on-line registration. Tracking is robust to occlusions, displacements, and most shape distortions. This work-flow friendly data collection method provides highly accurate and precise three-dimensional surface data to drive an image guidance system for breast conserving surgery.