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This work presents the development of a multi-spectral vision system that combines
different technologies detecting radiation in the visible spectrum (380-750 nm wavelengths),
in the near-infrared NIR (1550 nm wavelengths), in the thermal spectrum
band 1.4μm, and 77 GHz millimeter band. The main motivation of the this work
is to propose a new hyper...
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... half spaces on the convex hull, (d) the power diagram cells of the poles, labeled inner and outer, and (e) the power crust and the power shape of its interior solid [27] Experimental setup for evaluation of the NIR-SPI vision system:(a) NIR-SPI vision system with active illumination in the wavelength 1550 nm at configuration back modulation (see Fig. 1 Test-bench configuration used reproduce to the effect of an absorbing/scattering medium on imaging: (a) monostatic configuration of the light source and the co-located detector, and the object reflection is provided with contrast. In the side-illuminated configuration, the light source illuminates the scattering medium and the object ...
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... process allowed for restoring an image by using each separate color channel output, respectively, and obtaining a unified color image by combining these outputs.Other types of applications using the single-pixel imaging approach include the creation of 3D images [42], video streams, hyperspectral applications including a combination of infrared images and images obtained in the visible range, or including 3D images obtained by applying the TOF principle, or even adding radar systems to the mix. A timeline showing all these developments can be observed in Figure 1.1. ...
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... 1.1 and 1.2 show a timeline with different developments mentioned, used in single-pixel imaging systems, including modulation technologies, sampling, and processing schemes, respectively, developed between 1982 and 2020. Figure 1.3: Evolution of the RADAR technologies from fixed to antenna-on-chip devices. ...
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... pulsed radar, which radiated differentiated pulses generated using a spark. Hülsmeyer's ideas are based on Heinrich Hertz's experiments performed and published in 1888 when Hertz detected the polarization-dependent reflection of electromagnetic waves [54]. Since then, radar system technology and signal processing have significantly improved (see Fig. 1 [56,57], which offer bandwidth control advantage through the use of multiplecarriers and enhancements of the ambiguity function compared to LFM modulation methods by integrating a cyclic code ...
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... imaging is based on the principle of spatial modulation of light. It relies on the projection of a sequence of structured illumination patterns, generated using light modulation devices such as SLM, Digital Micromirror Devices (DMD), or other similar modulators (see Fig. 1.1), onto the object to be imaged. The detection of this modulated light reflected by the object, using a system of lens for focusing, is performed by a single photodiode that delivers an output voltage signal equivalent to the amount of light detected. The relation between the structured illumination pattern and the light signal ...
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... the reconstructed image is expressed as the inner product of the output voltage signal obtained in each measurement and the structured pattern applied to obtain it. The spatial light modulation in single-pixel imaging can be carried out following two different schemes [72]: (1) a structured illumination scheme named front modulation (depicted in Fig.1.4a, and (2) a structured detection scheme named back modulation (and depicted in Fig.1.4b). ...
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... small scattering particles (see Fig. 3.1a), the distribution of the scattered light is symmetric in the forward and backward directions. If the particle size increases, the scattered energy increases in the direction of the incident beam diminishing the amount of scattered light in the opposite direction [154] (see Fig. 3.1b -3.1c). The scattering cross-section Q d [155] is ...
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... small scattering particles (see Fig. 3.1a), the distribution of the scattered light is symmetric in the forward and backward directions. If the particle size increases, the scattered energy increases in the direction of the incident beam diminishing the amount of scattered light in the opposite direction [154] (see Fig. 3.1b -3.1c). The scattering cross-section Q d [155] is proportional to the radiation-particle interaction probability and it is defined through the so-called effective area of collision, for which the total scattering of the impinging light is proportional to the cross-section (Mie theory [156]) multiplied by the amount of the particles present in ...
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... Modeling of the scene: the third consideration defines the scene illumination as diffuse, and for the terrain surface reflectivity we consider the factor I o F k [178] -where I o is the radiance of the sky (in W m −1 sr −1 ) and F k is the local reflectance factor of the terrain (e.g. a wet or a dry surface)-, as defined through Eq. (3.19) defining the irradiation J t (k) at the object position, considering the local reflectance of the object in terms of the focal aperture (pinhole) k of the camera system. In Eq. (3.19), Ω k -defined through Eq. (3.20) [175]is a geometric constant associated with the optical parameters of the vision system, where A pixel is the photoactive area of the photodetector, f f ocalength is the focal length of the camera, and x k and y k define the 2D position of the single photodetector (pixel) referred to the optical center in the image plane. ...
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... this work, we propose a NIR-SPI vision system of the back modulation type (see Fig. 1.4b) based on active illumination provided through a NIR 8x8 LEDs matrix emitting with the 1550 nm wavelength, and a external InGaAs photodiode sensor. This configuration of active light illumination offers some advantages as it can operate under low-vision conditions (scenarios with dust, fog, rain, or smoke), and less sensitive to ...
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... x 45 cm 3 , the illumination of the scene was carried out using a semi-direct curve-type source light (see Fig. 5.28b) with a light beam view angle of 60 o . Figure 5.28: Experimental setup for evaluation of the NIR-SPI vision system:(a) NIR-SPI vision system with active illumination in the wavelength 1550 nm at configuration back modulation (see Fig. 1.4a) testing bench with controlled illumination background range of intensity between 0 to 50 KLux, (b) polar intensity diagram of the semi-direct light source used for the test bench. Figure 5.29: Scattering effect caused by a particle of water interacting with active illumination where the dispersion angle φ increases for droplet ...
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... already explained in detail, we propose using the structured illumination (see Fig. 1.4b) approach to be applied to the NIR-SPI system prototype, based on active illumination provided by an array of 8 x 8 NIR LEDs emitting radiation with a peak wavelength of 1550 nm. In this first evaluation, we made a 2D reconstruction of the different objects: a sphere with a 50 mm diameter, a torus shaped object with an external ...
