Concept: Single-lens reflex camera
Photometric stereo is a three dimensional (3D) imaging technique that uses multiple 2D images, obtained from a fixed camera perspective, with different illumination directions. Compared to other 3D imaging methods such as geometry modeling and 3D-scanning, it comes with a number of advantages, such as having a simple and efficient reconstruction routine. In this work, we describe a low-cost accessory to a commercial digital single-lens reflex (DSLR) camera system allowing fast reconstruction of 3D objects using photometric stereo. The accessory consists of four white LED lights fixed to the lens of a commercial DSLR camera and a USB programmable controller board to sequentially control the illumination. 3D images are derived for different objects with varying geometric complexity and results are presented, showing a typical height error of <3 mm for a 50 mm sized object.
The point of origin of an impact pattern is important in establishing the chain of events in a bloodletting incident. In this study, the accuracy and reproducibility of the point of origin estimation using the FARO Scene software with the FARO Focus(3D) laser scanner was determined. Five impact patterns were created for each of three combinations of distances from the floor (z) and the front wall (x). Fifteen spatters were created using a custom impact rig, scanned using the laser scanner, photographed using a DSLR camera, and processed using the Scene software. Overall results gave a SD = 3.49 cm (p < 0.0001) in the x-direction, SD = 1.14 cm (p = 0.9291) in the y-direction, and SD = 9.08 cm (p < 0.0115) in the z-direction. The technique performs within literature ranges of accepted accuracy and reproducibility and is comparable to results reported for other virtual stringing software.
Artificial skyglow is constantly growing on a global scale, with potential ecological consequences ranging up to affecting biodiversity. To understand these consequences, worldwide mapping of skyglow for all weather conditions is urgently required. In particular, the amplification of skyglow by clouds needs to be studied, as clouds can extend the reach of skyglow into remote areas not affected by light pollution on clear nights. Here we use commercial digital single lens reflex cameras with fisheye lenses for all-sky photometry. We track the reach of skyglow from a peri-urban into a remote area on a clear and a partly cloudy night by performing transects from the Spanish town of Balaguer towards Montsec Astronomical Park. From one single all-sky image, we extract zenith luminance, horizontal and scalar illuminance. While zenith luminance reaches near-natural levels at 5 km distance from the town on the clear night, similar levels are only reached at 27 km on the partly cloudy night. Our results show the dramatic increase of the reach of skyglow even for moderate cloud coverage at this site. The powerful and easy-to-use method promises to be widely applicable for studies of ecological light pollution on a global scale also by non-specialists in photometry.
Camera traps are valuable sampling tools commonly used to inventory and monitor wildlife communities but are challenged to reliably sample small animals. We introduce a novel active camera trap system enabling the reliable and efficient use of wildlife cameras for sampling small animals, particularly reptiles, amphibians, small mammals and large invertebrates. It surpasses the detection ability of commonly used passive infrared (PIR) cameras for this application and eliminates problems such as high rates of false triggers and high variability in detection rates among cameras and study locations. Our system, which employs a HALT trigger, is capable of coupling to digital PIR cameras and is designed for detecting small animals traversing small tunnels, narrow trails, small clearings and along walls or drift fencing.
Collections of biological specimens are fundamental to scientific understanding and characterization of natural diversity-past, present and future. This paper presents a system for liberating useful information from physical collections by bringing specimens into the digital domain so they can be more readily shared, analyzed, annotated and compared. It focuses on insects and is strongly motivated by the desire to accelerate and augment current practices in insect taxonomy which predominantly use text, 2D diagrams and images to describe and characterize species. While these traditional kinds of descriptions are informative and useful, they cannot cover insect specimens “from all angles” and precious specimens are still exchanged between researchers and collections for this reason. Furthermore, insects can be complex in structure and pose many challenges to computer vision systems. We present a new prototype for a practical, cost-effective system of off-the-shelf components to acquire natural-colour 3D models of insects from around 3 mm to 30 mm in length. (“Natural-colour” is used to contrast with “false-colour”, i.e., colour generated from, or applied to, gray-scale data post-acquisition.) Colour images are captured from different angles and focal depths using a digital single lens reflex (DSLR) camera rig and two-axis turntable. These 2D images are processed into 3D reconstructions using software based on a visual hull algorithm. The resulting models are compact (around 10 megabytes), afford excellent optical resolution, and can be readily embedded into documents and web pages, as well as viewed on mobile devices. The system is portable, safe, relatively affordable, and complements the sort of volumetric data that can be acquired by computed tomography. This system provides a new way to augment the description and documentation of insect species holotypes, reducing the need to handle or ship specimens. It opens up new opportunities to collect data for research, education, art, entertainment, biodiversity assessment and biosecurity control.
We investigated probable functions of the interacting genitalic components of a male and a female of the flightless grasshopper species Melanoplus rotundipennis (Scudder, 1878) (frozen rapidly during copulation) via correlative microscopy; in this case, by synergizing micro-computed tomography (micro-CT) with digital single lens reflex camera photography with focal stacking, and scanning electron microscopy. To assign probable functions, we combined imaging results with observations of live and museum specimens, and function hypotheses from previous studies, the majority of which focused on museum specimens with few investigating hypotheses in a physical framework of copulation. For both sexes, detailed descriptions are given for each of the observed genitalic and other reproductive system components, the majority of which are involved in copulation, and we assigned probable functions to these latter components. The correlative microscopy approach is effective for examining functional morphology in grasshoppers, so we suggest its use for other animals as well, especially when investigating body regions or events that are difficult to access and understand otherwise, as shown here with genitalia and copulation. J. Morphol., 2017. © 2017 Wiley Periodicals, Inc.
Tumor necrosis factor-α (TNF-α) is a significant mediator of autoimmune diseases and an inflammatory protein biomarker. A novel method for the immunotargeting of TNF-α has been developed using three-dimensional (3D) enhanced dark-field super-resolution microscopy (3D EDF-SRM) based on ultra-sensitive dual-code plasmonic nanosensing. Dual-code EDF-based 3D SRM improved the localization precision and sensitivity with a least-cubic algorithm, which provides accurate position information for the immunotargeted site. A dual-view device and digital single lens reflex (DSLR) camera were used for simultaneous dual confirmable quantitative and qualitative immunoscreening based on enhanced dark-field scattering images. Two different sizes of silver nanoparticles (40- and 80-nm AgNPs) were compared to enhance the scattering signal of the immunotargeted plasmonic nanoprobe for the 3D EDF-SRM system. The standard TNF-α was immunotargeted at a single-molecule level and was quantitatively analyzed by measuring the scattering signals of 80-nm AgNPs on an array chip with gold-nanostages (GNSs) with 100-nm spot diameters. The localization precision in the 80-nm AgNP immunotag on the GNS narrowed to ~ 9.5 nm after applying the least-cubic algorithm. The developed nanosensor exhibited a detection limit of 65 zM (1.14 ag/mL; S/N = 3) with a wide dynamic detection range of 65 zM-2.08 pM (1.14 ag/mL-36.4 pg/mL; R = 0.9921). These values are 20-33,400,000 times lower than detection limits obtained using previous methods. In addition, a recovery greater than 98% was achieved by spiking standard TNF-α into human serum samples. This method should facilitate simultaneous improvements in immunotargeting precision and ultra-high sensitive detection of various disease-related target protein molecules at a single-molecule level.
The purpose of this study is to illustrate motion correction in Musculoskeletal (MSK) Magnetic Resonance Imaging (MRI) through utilization of information from an optical tracker to capture the extent and instant of motion. A Digital Single Lens Reflexive camera is employed as the optical tracker to capture the extent and instant of motion. A checkerboard is utilized as a marker that is placed on the coil. Shift of the checkerboard provides the extent of motion, which is captured by camera and is used for motion correction in (MSK)-MRI images. Experiments were first performed on an in vitro phantom to obtain calibration curves, which determine the relationship between object movement and pixel shifts. Six healthy volunteers were recruited for the study and experiments were repeated thrice on each subject. Reducing the gradient entropy of the image with reference to the calibration curve resulted in motion correction. Fusion of motion-free data with motion-corrupted data and motion free data with motion-corrected data was performed for qualitative analysis of data. Normalized Root Mean Squared Error of the motion-corrected data with respect motion-free was approximately 20% lesser compared to motion-corrupted data with respect to motion-free data with better delineation of edges and reduced ghosting. The work focuses on time of displacement through an external tracker on the RF coil and utilizes that information for motion correction. The method can be readily implemented on a clinical scanner, while it is not necessary for the subject to wear motion sensors.
Over the past decade, Structure from Motion (SfM) has increasingly been used as a means of digital preservation and for documenting archaeological excavations, architecture, and cultural material. However, few studies have tapped the potential of using SfM to document and analyze taphonomic processes affecting burials for forensic sciences purposes. This project utilizes SfM models to elucidate specific post-depositional events that affected a series of three human cadavers deposited at the South East Texas Applied Forensic Science Facility (STAFS). The aim of this research was to test the ability for untrained researchers to employ spatial software and photogrammetry for data collection purposes. For a series of three months a single lens reflex (SLR) camera was used to capture a series of overlapping images at periodic stages in the decomposition process of each cadaver. These images are processed through photogrammetric software that creates a 3D model that can be measured, manipulated, and viewed. This project used photogrammetric and geospatial software to map changes in decomposition and movement of the body from original deposition points. Project results indicate SfM and GIS as a useful tool for documenting decomposition and taphonomic processes. Results indicate photogrammetry is an efficient, relatively simple, and affordable tool for the documentation of decomposition.
The purpose of this study is to describe the use of commercial digital single light reflex (DSLR) for vitreoretinal surgery recording and compare it to standard 3-chip charged coupling device (CCD) camera.