Multi-line Detection Research Articles

Wood broken defect detection with laser profilometer based on Bi-LSTM network

Detecting wood broken defects through machine vision is challenging due to the similar appearance of defect and defect-free regions on images. Laser profilometer is a reasonable solution, nevertheless, imperfect point cloud representation, such as slope profile, incontinuity of tiny defects and similarity between broken defects and sound area, poses obstacles. To overcome these challenges, this study proposes a multi-line detection method based on bidirectional long- and short-term memory network (Bi-LSTM) for real-time wood broken defect detection. The feature that represents the extent of surface damage in line-level is designed by residual extraction and sorting operation. The Bi-LSTM combines adjacent information to exaggerate semantic information of detection line. Context information extracted by Bi-LSTM are concatenated for multi-line detection to reduce computation complexity. Finally, detection results are modified by considering the information of adjacent lines of point cloud. Experimental results show that the proposed method achieves real-time detection with high accuracy.

Differential synthetic illumination based on multi-line detection for resolution and contrast enhancement of line confocal microscopy.

Line confocal (LC) microscopy is a fast 3D imaging technique, but its asymmetric detection slit limits resolution and optical sectioning. To address this, we propose the differential synthetic illumination (DSI) method based on multi-line detection to enhance the spatial resolution and optical sectioning capability of the LC system. The DSI method allows the imaging process to simultaneously accomplish on a single camera, which ensures the rapidity and stability of the imaging process. DSI-LC improves X- and Z-axis resolution by 1.28 and 1.26 times, respectively, and optical sectioning by 2.6 times compared to LC. Furthermore, the spatially resolved power and contrast are also demonstrated by imaging pollen, microtubule, and the fiber of the GFP fluorescence-labeled mouse brain. Finally, Video-rate imaging of zebrafish larval heart beating in a 665.6 × 332.8 µm2 field-of-view is achieved. DSI-LC provides a promising approach for 3D large-scale and functional imaging in vivo with improved resolution, contrast, and robustness.

Hierarchical clustering for line detection with UAV images and an application for the estimation of the clearance volume of oyster stones

Mariculture can meet the increasing demand for seafood but may lead to significant environmental pollution in coastal zones. Remote sensing with UAVs is used in this paper to estimate the clearance volume as part of a coastal ecological restoration project in an oyster breeding area. First, a mathematical model for multiline detection is established based on the linear distribution of maricultures, and the minimum cosine distance sum is used as the judgment basis in the clustering algorithm. Second, an algorithm for hierarchical clustering line detection is proposed, and the centerline of marine breeding is determined. Then, the clearance volume is estimated using a three-point estimation scheme. The oyster breeding area in Xiamen between Dadeng Island and Xiaodeng Island is selected as the experimental area, it is determined that the clearance volume of oyster stones can be estimated with an accuracy of 93.4%. Finally, the factors associated with improvements in the accuracy of hierarchical clustering linear detection are analyzed and discussed.

Efficient multi-plane extraction from massive 3D points for modeling large-scale urban scenes

In modeling large-scale urban scenes, extracting reliable dominant planes from initial 3D points plays an important role for inferring the complete scene structures. However, traditional local and global methods are frequently prone to missing many real planes and also appear powerless when massive 3D points are present. To solve these problems, the paper presents an efficient multi-plane extraction method based on scene structure priors. The proposed method first explores the potential relations between the planes by detecting 2D line segments in the projection map produced from initial 3D points (i.e., simplify 3D model to 2D model), including: (1) multi-line detection in regions by the guidance of scene structure priors; (2) multi-line detection between regions under the Markov Random Field framework incorporating scene structure priors. Then, according to the resulting plane relations, a rapid multi-plane generation is carried out instead of the time-consuming plane fitting over 3D points. Experimental results confirm that the proposed method can efficiently produce sufficient and reliable dominant planes from a vast number of noisy 3D points (only about 8 s on 2000K 3D points) and can be applied for modeling large-scale urban scenes.

CONSTRAINING THE ABUNDANCES OF COMPLEX ORGANICS IN THE INNER REGIONS OF SOLAR-TYPE PROTOSTARS

The high abundances of Complex Organic Molecules (COMs) with respect to methanol, the most abundant COM, detected towards low-mass protostars, tend to be underpredicted by astrochemical models. This discrepancy might come from the large beam of the single-dish telescopes, encompassing several components of the studied protostar, commonly used to detect COMs. To address this issue, we have carried out multi-line observations of methanol and several COMs towards the two low-mass protostars NGC1333-IRAS2A and -IRAS4A with the Plateau de Bure interferometer at an angular resolution of 2 arcsec, resulting in the first multi-line detection of the O-bearing species glycolaldehyde and ethanol and of the N-bearing species ethyl cyanide towards low-mass protostars other than IRAS 16293. The high number of detected transitions from COMs (more than 40 methanol transitions for instance) allowed us to accurately derive the source size of their emission and the COMs column densities. The COMs abundances with respect to methanol derived towards IRAS2A and IRAS4A are slightly, but not substantitally, lower than those derived from previous single-dish observations. The COMs abundance ratios do not vary significantly with the protostellar luminosity, over five orders of magnitude, implying that low-mass hot corinos are quite chemically rich as high-mass hot cores. Astrochemical models still underpredict the abundances of key COMs, such as methyl formate or di-methyl ether, suggesting that our understanding of their formation remains incomplete.

Multi-line detection of O2towardρOphiuchi A

Models of pure gas-phase chemistry in well-shielded regions of molecular clouds predict relatively high levels of molecular oxygen, O2, and water, H2O. Contrary to expectation, the space missions SWAS and Odin found only very small amounts of water vapour and essentially no O2 in the dense star-forming interstellar medium. Only toward rho Oph A did Odin detect a weak line of O2 at 119 GHz in a beam size of 10 arcmin. A larger telescope aperture such as that of the Herschel Space Observatory is required to resolve the O2 emission and to pinpoint its origin. We use the Heterodyne Instrument for the Far Infrared aboard Herschel to obtain high resolution O2 spectra toward selected positions in rho Oph A. These data are analysed using standard techniques for O2 excitation and compared to recent PDR-like chemical cloud models. The 487.2GHz line was clearly detected toward all three observed positions in rho Oph A. In addition, an oversampled map of the 773.8GHz transition revealed the detection of the line in only half of the observed area. Based on their ratios, the temperature of the O2 emitting gas appears to vary quite substantially, with warm gas (> 50 K) adjacent to a much colder region, where temperatures are below 30 K. The exploited models predict O2 column densities to be sensitive to the prevailing dust temperatures, but rather insensitive to the temperatures of the gas. In agreement with these model, the observationally determined O2 column densities seem not to depend strongly on the derived gas temperatures, but fall into the range N(O2) = (3 to >6)e15/cm^2. Beam averaged O2 abundances are about 5e-8 relative to H2. Combining the HIFI data with earlier Odin observations yields a source size at 119 GHz of about 4 - 5 arcmin, encompassing the entire rho Oph A core.

Isotope selective analysis of CO(2) with tunable diode laser (TDL) spectroscopy in the NIR.

The performance of a home-built tunable diode laser (TDL) spectrometer, aimed at multi-line detection of carbon dioxide, has been evaluated and optimized. In the regime of the (30(0)1)(III) <-- (000) band of (12)CO(2) around 1.6 microm, the dominating isotope species (12)CO(2), (13)CO(2), and (12)C(18)O(16)O were detected simultaneously without interference by water vapor. Detection limits in the range of few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in a long-path absorption cell set-up. High sensitivity in conjunction with high precision -- typically +/-1 (per thousand) and +/-6 (per thousand) for 3% and 0.7% of CO(2), respectively -- renders this experimental approach a promising analytical concept for isotope-ratio determination of carbon dioxide in soil and breath gas. For a moderate (12)CO(2) line, the pressure dependence of the line profile was characterized in detail, to account for pressure effects on sensitive measurements.

Automatic matrix dependent wavelength selection in inductively coupled plasma atomic emission spectrometry with multi-line detection

The best wavelengths for the determination of desired components in a set of binary and ternary mixtures may be selected without prior knowledge of the nature of any interfering components. Automatic line selection allows the matrix dependent tailoring of the lines chosen to the element or elements of interest. Factor analysis facilitates the selection process by identifying those wavelengths where an unidentified interferent contributes to the measured intensity. A multivariate analysis based on selected wavelengths gives the concentrations of all desired components while avoiding error in these concentrations due to interferents.