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Significance: Hyperspectral imaging (HSI) has emerged as a promising optical technique. Besides optical properties of a sample, other sample physical properties also affect the recorded images. They are significantly affected by the sample curvature and sample surface to camera distance. A correction method to reduce the artifacts is necessary to reliably extract sample properties. Aim: Our aim is to correct hyperspectral images using the three-dimensional (3D) surface data and assess how the correction affects the extracted sample properties. Approach: We propose the combination of HSI and 3D profilometry to correct the images using the Lambert cosine law. The feasibility of the correction method is presented first on hemispherical tissue phantoms and next on human hands before, during, and after the vascular occlusion test (VOT). Results: Seven different phantoms with known optical properties were created and imaged with a hyperspectral system. The correction method worked up to 60 deg inclination angle, whereas for uncorrected images the maximum angles were 20 deg. Imaging hands before, during, and after VOT shows good agreement between the expected and extracted skin physiological parameters. Conclusions: The correction method was successfully applied on the images of tissue phantoms of known optical properties and geometry and VOT. The proposed method could be applied to any reflectance optical imaging technique and should be used whenever the sample parameters need to be extracted from a curved surface sample.

A method for simultaneous laser profilometer and hand–eye calibration in relation to an industrial robot as well as its implementation is presented. In contrast to other methods, the new calibration procedure requires the measurement of only one reference geometry to calculate all the transformation parameters. The reference geometry is measured with a laser profilometer from 15 different poses. The intrinsic parameters of the profilometer, as well as the extrinsic (hand–eye) parameters, are then numerically optimized to achieve the minimum deviation between the reference and the measured geometry. The method was characterized with experiments that revealed a standard deviation of the displacements between the reference geometry after the calibration of less than 0.105 mm in the case of using the robot-arm actuator and 0.046 mm in case of using a 5-axis CNC milling machine. The entire procedure, including measurement and calculation, can be completely automated and lasts less than 10 min. This opens up possibilities for regular on-site recalibration of the entire system.

Optical imaging systems use a light source that illuminates a sample and a photodetector that detects light reflected from or transmitted through the sample. The sample surface curvature, surface-to-camera distance, and illumination-source-to-surface distance significantly affect the measured signal, resulting in image artifacts. To correct the images, a three-dimensional (3D) profilometry system was used to obtain 3D surface information. The 3D information enables image correction using Lambert cosine law and height correction. In this study, the feasibility of the correction method for push-broom hyperspectral imaging of three different objects is presented. Results show a significant reduction of image artifacts, making further image analysis more accurate and robust. The presented 3D profilometry method is applicable to all push-broom imaging systems and the described correction procedure can be applied to all spectral or monochromatic imaging systems.

Curvature and height corrections were made on hyperspectral images in order to reduce intensity dependence on distance and inclination. The corrections were made by Lambertian cosine law and measured 3D surface of the sample. Image of homogeneous phantom appeared significantly more homogeneous after correction.

Background Measuring wound dimensions is important for monitoring and predicting the healing process. In our paper we propose and validate a handheld measuring system with dedicated software for measuring wound dimensions. Methods The measuring system comprises a commercial DSLR camera and a light pattern projection system. It is based on triangulation and structured illumination principles which enable handheld measuring. An edge of the wound is detected from the colour information of the measurement. Across the area of the wound, virtual healthy skin is approximated which enables the calculation of the wound volume and area, in addition to the wound circumference, which is calculated from the detected edge. Results In vitro verification using virtual standards showed that the accuracy of the analysis software is over 95% and 93% for measuring the area and volume respectively. A significant part of the error can be attributed to the inability of approximation to replicate entirely missing features. The accuracy of measuring the volume reduced to about 89% when a 3D measuring step was included in the analysis. When measuring in vivo wounds, the unrepeatability of the system was under 8% for measuring the area, which is a bit lower than comparable systems, and 5% for measuring the volume, which is about 4 times lower. Conclusion Based on these results and the ease of use, we conclude that the system is suitable to be used in daily clinical practice for measuring wound dimensions.

This paper presents development of three-dimensional characterization of concrete abrasion using the ASTM C1138 test method, which simulates underwater abrasion. To this effect, a measuring system was designed based on laser triangulation with linear illumination of the surface measured. The system allows for contactless, quick and precise measuring of average wear and other topological characteristics dependent on the type of the tested concrete. Validation results show that the system’s precision is better as conventional weighting method (

International audience; Laser ranging is a measurement method, applied in a wide range of applications. In this study, laser ranging is used to measure the height of turbulent water flows. Measurements were performed in three cross sections of a confluence where a tributary flow meets the main flow. Both flows exhibited high Reynolds and Froude numbers where the free-water surface profiles were turbulent, non-stationary and non-homogeneous. Measurements were taken using a commercial LIDAR and a high-speed camera. The high-speed camera was operated on the principle of laser triangulation, using only the illumination from the LIDAR laser beam. Since, no other state-of-the-art method for measuring instantaneous water surface profiles exists, LIDAR and triangulation methods could only be compared with each other. The results show good agreement between both methods for the average turbulent water profile and fair agreement for instantaneous profiles. Presented herein is an explanation of these results.

In medicine and cosmetics a need has arisen for an accurate, fast, simple and broadly applicable three-dimensional skin surface measuring system. A new development of such handheld optical device that uses white light Fourier transform profilometry for skin surface topography measurement is presented here. The device is based on a commercially available DSLR camera and a newly designed optical system which projects a Ronchi grating pattern on the measured surface and records its image. The 3D surface is reconstructed from a single image. The topography is described using four surface roughness parameters: mean absolute deviation Rsuba , root-mean-square deviation Rsubq skewness Rsubsk and kurtosis Rsubku . Experimental measurements were conducted on five facial skin areas, together belonging to three people, before and after the laser skin treatment therapy, to evaluate its effects on skin surface roughness. The results show the viability and usefulness of the developed optical system for skin topography measurement. V članku je predstavljena nova ročna optična naprava, ki uporablja Fourierjevo transformacijsko profilometrijo z belo svetlobo za merjenje topografije kože. V medicini in kozmetiki se pojavlja potreba po natančnem, hitrem, enostavnem in široko uporabnem sistemu za tridimenzionalno in-vivo merjenje površine kože. Taka optična naprava bi dajala natančne in konsistentne informacije o topografiji in barvi kože, pri čemer bi bilo brezdotično in neinvazivno merjenje globine njena najpomembnejša novost.

Background Knowing the orientation of the head is important in many fields, including medicine. Many methods and measuring systems exist, but usually they use different markers or sensors attached to the subject’s head for head orientation determination. In certain applications these attachments may represent a burden or a distraction to the subject under study which may have an unfavourable impact on the measurement. We propose a non-contact optical method for head-to-trunk orientation measurement that does not require any attachments to the subject under study. Methods An innovative handheld 3D apparatus has been developed for non-invasive and fast 3D shape measurements. It is based on the triangulation principle in combination with fringe projection. The shape of the subject’s upper trunk and head is reconstructed from a single image using the Fourier transform profilometry method. Two shape measurements are required to determine the head-to-trunk orientation angles: one in the reference (neutral) position and the other one in the position of interest. The algorithm for the head-to-trunk orientation angle extraction is based on the separate alignment of the shape of the subject’s upper trunk and head against the corresponding shape in the reference pose. Single factor analysis of variance (ANOVA) was used for statistical characterisation of the method precision. Results The method and the 3D apparatus were verified in-vitro using a mannequin and a reference orientation tracker. The uncertainty of the calculated orientation was 2°. During the in-vivo test with a human subject diagnosed with cervical dystonia (aged 60), the repeatability of the measurements was 3°. In-vitro and in-vivo comparison was done on the basis of an experiment with the mannequin and a healthy male (aged 29). These results show that only the difference between flexion/extension measured angles was statistically significant. The differences between means were less than 1° for all ranges. Conclusions The new non-contact method enables the compensation of the movement of the measuring instrument or the subject’s body as a whole, is non-invasive, requires little additional equipment and causes little stress for the subject and operator. We find that it is appropriate for measurements of the head orientation with respect to the trunk for the characterization of the cervical dystonia.

A system for adaptive robotic deburring with a correction of the errors in workpiece positioning is presented. The correction is based on 3D measurements of the workpiece's surface and its registration to the target surface, measured on a reference workpiece. The surface measurement is performed with a laser-triangulation profilometer. The reference tool path is determined using robot teaching on the reference, already deburred, workpiece. The positioning errors of the currently processed workpiece are compensated by tool path adaptation in accordance with the registration results by means of rotation and translation. The experiments showed that the average precision of localization is 0.06 mm and the average bias between the true and measured values is 0.23 mm. The developed adaptive system is also applicable in other similar applications where it is difficult to ensure repeatable clamping of the workpiece. Nastanek igle pri ulitkih predstavlja velik problem, saj lahko poškoduje delavca in zmanjšuje kakovost samega izdelka. Ročno razigljevanje je dolgotrajen, zahteven in drag proces odstranjevanja materiala igle, zato je potreba po avtomatizaciji procesa očitna. Večina sistemov za robotsko razigljevanje temelji na premikanju obdelovanca z robotsko roko pod orodjem za razigljevanje. Pot robotske roke je običajno določena s postopkom robotskega učenja, kjer operater na referenčnem obdelovancu določi množico točk, prek katerih nato robot premika obdelovanec. Pri tem se predpostavlja, da so vsi nadaljnji obdelovanci enake oblike in se nahajajo na isti lokaciji. Medtem ko je prvi prepostavki pri razigljevanju ulitkov lahko zadostiti, je točen položaj obdelovanca odvisen predvsem od njegovega vpetja v robotsko roko. Običajen pristop je zagotovitev ponovljivega vpenjanja obdelovanca v robotsko roko, kar je v primeru ulitkov zelo težko zagotoviti. Drug pristop, ki je predstavljen v tem prispevku, pa temelji na adaptaciji poti robotske roke glede na izmerjen položaj trenutno vpetega obdelovanca.