Surface Of Target Object Research Articles

An alternative approach for detecting cavities in reinforced concrete structures using GPR A-scan data

This paper introduces an alternative approach for detecting cavities in reinforced concrete walls using Ground Penetrating Radar (GPR) A-scan data. GPR, leveraging electromagnetic waves, is extensively applied for cavity detection within structures. The nature of electromagnetic waves, significantly influenced by reflective media and attenuating through them, requires specialized analysis methods for data interpretation. Traditional methods often involve identifying and eliminating overlapping reflection patterns or adjusting signal magnitude at specific depths to isolate peak signals from the target object's surface, which can be subjective and complex. To overcome these challenges, this study proposes quantitatively assessing the presence of cavities by analyzing the integral area of A-scan data within suspected ranges. Observations indicate a substantial difference in reflection patterns between areas with and without cavities, showcasing the potential of this approach for quantitative cavity detection. This approach offers a more objective and quantitative basis for identifying cavities in reinforced concrete structures.

BimodalPS: Causes and Corrections for Bimodal Multi-Path in Phase-Shifting Structured Light Scanners.

Structured light illumination is an active 3D scanning technique based on projecting and capturing a set of striped patterns and measuring the warping of the patterns as they reflect off a target object's surface. As designed, each pixel in the camera sees exactly one pixel from the projector; however, there are multi-path situations where a camera pixel sees light from multiple projector positions. In the case of bimodal multi-path, the camera pixel receives light from exactly two positions, which occurs along a step edge where the edge slices through a pixel which, therefore, sees both a foreground and background surface. In this paper, we present a general mathematical model to address this bimodal multi-path issue in a phase-shifting or so-called phase-measuring-profilometry scanner to measure the constructive and destructive interference between the two light paths, and by taking advantage of this interference, separate the paths and make two decoupled depth measurements. We validate our algorithm with both simulations and a number of challenging real-world scenarios, significantly outperforming the state-of-the-art methods.

Fourier Expression of the Quantum Radar Cross Section of a Dihedral Corner Reflector

In this paper, a Fourier expression of the quantum radar cross section (QRCS) of a dihedral corner reflector is proposed, which avoids the problems caused by atomic sampling on the target-object surface and is a powerful tool for analyzing the scattering characteristics of the reflector. We compare the result of the proposed expression with that of numerical calculations, and have preliminarily verified its correctness. On this basis, we discuss the influence of the wavelength of single photon pulses and the panel size of a dihedral corner reflector on QRCS in detail. Simulation results demonstrate that from a single factor of wavelength, a quantum radar using a small-wavelength quantum signal has better visibility to the reflector, and the quantum scattering intensity is proportional to the panel size. Compared with classical radar, quantum radar has an enhanced detection performance that is more stable within a wide angle range, which is insensitive to the wavelength of the quantum signal and panel size of the reflector and is helpful for the detection of stealth targets.

DEVELOPING A 3D WAVEFORM LIDAR SIMULATOR FOR FOREST

Abstract. Waveform LiDAR systems is widely used in several fields such as terrain survey, disaster monitoring and forest monitoring. Especially, in forest research, using an echo signal is expected for understanding structural characteristics of the forest. However, an echo signal highly depends on the sensor configuration, the footprint size, the canopy structure, and terrain condition. Therefore, it is not easy to understand the forest attributes from the echo signal. In this paper, we describe the development and application of model which to simulate laser intersections within ideal forest environments and to visualize intersections. The developed model has three components. The first component was a creation of the forest environment as full polygon in 3DCG software. Characteristics of the forest was decided by individual trees which were generated by the plant growth model using species and planting years as the initial parameter. The second component was a simulation using a ray tracing to calculate intersections between the forest object and the modelled laser beam. In this study, a laser beam with a specific footprint and a pulse width was defined by spatiotemporal features. In point of view of spatial feature, numerous sub laser beams were generated within a specific footprint to make the laser beam hit the target uniformly. Each sub laser beam had the intensity which was calculated by both the distance from the center of laser beam and the TEM00. On the other hand, in point of view of time feature, each sub laser beam was defined as several particles based on the sampling rate. Each particle had the intensity which was calculated by the pulse width and the sampling rate. The third component was a creation of an echo signal of a specific footprint using the calculated intersections and its intensity, reflectance of target at intersections and sampling rate. Moreover, the developed model had a view function that was able to show the calculated intersections on the surface of target object. As results of simulation of ideal forest environment scenarios, the developed model demonstrated that the model generated the echo signal of different environments well and the viewer function helped to understand the interactions between sub laser beams and target objects.