A COMPARISON OF LASER AND STRUCTURED LIGHT SCANNING TECHNOLOGIES FOR ARCHAEOLOGICAL APPLICATIONS

Reverse engineering and in particular three-dimensional digitization have become an essential part of the documentation of archaeological findings. 3D scanning produces a high-precision digital reference document. The factors that influence the quality of the 3D scanned data are the scanned object’s surface colour, its glossiness and geometry, and the ambient light during the scanning process. However, the actual equipment and scanning technologies are of primary importance. The current paper presents a qualitative and quantitative comparison between two 3D scanning devices of different technologies; structured light 3D scanning and laser 3D scanning. The benchmark for this comparison is an ancient Roman vase from the city of Thessaloniki, Greece. The object was scanned with every possible setting on each scanner, but only one configuration of settings on each device was selected for the final comparison. The main criterion for the final selection of the two 3D models acquired with the use of the two technologies was the proximity in the number of points and polygons produced for digitally restoring the ancient vase in the best possible way. The results indicate important differences regarding the accuracy of the final digital model. The laser technology produced better accuracy but with a significant cost in scanning time and model data size. On the other hand, the structured light technology achieved the optimal combination of scanning quality and accuracy, along with reduced acquisition time of scan data.

The Use of Smartphone Photogrammetry to Digitise Transtibial Sockets: Optimisation of Method and Quantitative Evaluation of Suitability

The fit of a lower limb prosthetic socket is critical for user comfort and the quality of life of lower limb amputees. Sockets are conventionally produced using hand-crafted patient-based casting techniques. Modern digital techniques offer a host of advantages to the process and ultimately lead to improving the lives of amputees. However, commercially available scanning equipment required is often expensive and proprietary. Smartphone photogrammetry could offer a low cost alternative, but there is no widely accepted imaging technique for prosthetic socket digitisation. Therefore, this paper aims to determine an optimal imaging technique for whole socket photogrammetry and evaluate the resultant scan measurement accuracy. A 3D printed transtibial socket was produced to create digital and physical twins, as reference models. The printed socket was photographed from 360 positions and simplified genetic algorithms were used to design a series of experiments, whereby a collection of photos were processed using Autodesk ReCap. The most fit technique was used to assess accuracy. The accuracy of the socket wall volume, surface area and height were 61.63%, 99.61% and 99.90%, respectively, when compared to the digital reference model. The scanned model had a wall thickness ranging from 2.075 mm at the top to 7.758 mm towards the base of the socket, compared to a consistent thickness of 2.025 mm in the control model. The technique selected did not show sufficient accuracy for clinical application due to the degradation of accuracy nearer to the base of the socket interior. However, using an internal wall thickness estimation, scans may be of sufficient accuracy for clinical use; assuming a uniform wall thickness.

Impact of digital reference on the delivery of reference in New Zealand public libraries

<p>This study looks at digital reference services in New Zealand public libraries to find out what types of services are being provided and what impact they are having on traditional reference services. A survey was sent to twenty-seven selected public libraries with a further sixteen selected libraries added after a low response rate from the first group, to collect information on their digital reference services. The libraries included large, medium and small and were selected from all areas of New Zealand. A questionnaire was used to collect the information and the data was statistically analysed. All large and the majority of medium selected libraries are providing a digital reference service in the form of email or web form. Four of the large libraries are participating in AnyQuestions - a virtual reference service for New Zealand school children, and one large library has their own virtual service. The low response rate and deficiencies in the survey design have resulted in inconclusive results for this study. We know libraries are providing digital reference services and we know something about how the services are provided, but it is still unclear whether these services are having an impact on traditional reference services.</p>

Impact of digital reference on the delivery of reference in New Zealand public libraries

<p>This study looks at digital reference services in New Zealand public libraries to find out what types of services are being provided and what impact they are having on traditional reference services. A survey was sent to twenty-seven selected public libraries with a further sixteen selected libraries added after a low response rate from the first group, to collect information on their digital reference services. The libraries included large, medium and small and were selected from all areas of New Zealand. A questionnaire was used to collect the information and the data was statistically analysed. All large and the majority of medium selected libraries are providing a digital reference service in the form of email or web form. Four of the large libraries are participating in AnyQuestions - a virtual reference service for New Zealand school children, and one large library has their own virtual service. The low response rate and deficiencies in the survey design have resulted in inconclusive results for this study. We know libraries are providing digital reference services and we know something about how the services are provided, but it is still unclear whether these services are having an impact on traditional reference services.</p>

SPACE CALIBRATION OF THE ROBOT SYSTEM IN PUNCTURE SURGERY

Traditional manual puncture surgery has low positioning accuracy and poor stability. Moreover, the computed tomography method can cause strong radiation damage. Therefore, this study intends to establish a robotic system in puncture surgery, which is based on optical registration to improve safety, accuracy, and efficiency. As the accuracy of surgical space calibration influences the accuracy of the surgical system, this study proposes an improved automatic calibration algorithm for linear rotation. The algorithm can reduce error caused by manual calibration and system noise. Recalibration is not required provided that the pose of the digital reference frame is unchanged, thereby improving accuracy and efficiency. The proposed algorithm is experimentally verified to prove its effectiveness. Results show that the average errors of position and posture are 0.25[Formula: see text]mm and 0.2∘, respectively. The accuracy of calibration fully meets the needs of surgery.

A novel multidimensional strategy to evaluate Belamcanda chinensis (L) DC and Iris tectorum Maxim based on plant metabolomics, digital reference standard analyzer and biological activities evaluation

Background Belamcanda chinensis (L.) DC. (BC) belongs to the family of Iridaceae and is widely cultivated and used in many Chinese patent medicine and Chinese medicinal formulae. However, due to the high similarities in appearance such as color and shape to Iris tectorum Maxim (ITM), another plant from the same family, BC is often confused or even misused with ITM. Methods Therefore, in order to distinguish the chemical constituents, qualities and biological activities of BC and ITM, multiple technologies including plant metabolomics, digital reference standard (DRS) analyzer and biological activities assay were employed to provide a sufficient basis for their practical applications. Results In plant metabolomics, the PCA and OPLS-DA score plot indicated the obvious differences in chemical profiling between BC and ITM and 6 compounds were successfully identified to contribute to the differences. In DRS study, the fingerprints of 10 and 8 compounds in BC and ITM were developed based on DRS analyzer, respectively, involving relative retention time (RRT) method and linear calibration using two reference substances (LCTRS) technique. The DRS analyzer also accurately identified 10 and 8 compounds from BC and ITM, respectively, by using only two reference standards. In biological activities assay, BC had a better anticancer effect than ITM due to the high abundance of irigenin, while ITM showed stronger hepatoprotective activity than BC because of the high abundance of tectoridin. Conclusions Therefore, due to the significant differences of B. chinensis and I. dichotoma in chemical composition and biological activities, the current studies strongly proved that these two medicinal plants could not be mixed in industrial production and clinical medication.

Digital reference images when evaluating the quality of castings from aluminum and magnesium alloys

Reference X-ray images of defects in castings and welded joints have been used for many years in X-ray radiation inspection. With the transition to digital technologies, and the use of flat-panel detectors instead of radiographic film, the problem arose of creating reference digital images. Comparison of the digital image of the reference sample with the digital image of the test object can be carried out using software, which completely or partially excludes the subjective assessment of the operator, makes it possible to view doubtful areas of the image with magnification and without loss of contrast, automatically show the size of the defect, its intensity distribution by volume of the casting. All this makes the control more objective and productive. The reference images in the detector’s memory do not undergo the aging and degradation typical of X-ray images, and there is no need to replicate them.