Showing papers on "Viewing angle published in 1982"
TL;DR: In this article, a model for spectral emissivity is combined with the Planck function to calculate brightness temperature of snow in thermal infrared wavelengths for a range of grain sizes and viewing angles.
Abstract: Remote sensing of snowpack temperatures from satellites requires knowledge of the spectral emissivity of snow. A model for spectral emissivity is combined with the Planck function to calculate brightness temperature of snow in thermal infrared wavelengths for a range of grain sizes and viewing angles. Emissivity variations caused by density, grain shape, liquid water, and grain size are apparently unimportant, but emissivity varies with viewing angle to produce differences between thermodynamic temperature and brightness temperature as large as 3 K at wavelengths 12 to 14 μm, within the major atmospheric infrared window. This difference is also verified by experimental measurements. An equation to convert brightness temperatures to thermodynamic temperatures is presented, and this is also combined with a dual-wavelength atmospheric correction method. The spectral emissivity model is also used to calculate an ‘all-wave’ emissivity of snow: 0.985–0.990 for all grain sizes.
254 citations
TL;DR: An experimental simulation of a single-channel, double-angle viewing technique for the determination of sea surface temperature from satellite is presented in this paper, which relies upon the fact that the same area can be viewed simultaneously at two different angles (different air masses) by the geostationary satellite METEOSAT and by the polar orbiting satellite TIROS-N.
Abstract: An experimental simulation of a single-channel, double-angle viewing technique for the determination of sea surface temperature from satellite is presented. This method relies upon the fact that the same area can be viewed simultaneously at two different angles (different air masses) by the geostationary satellite METEOSAT and by the polar orbiting satellite TIROS-N. Extrapolating the two air mass observations to zero air mass is shown to give a value of the temperature in good agreement with the true sea surface temperature. A discussion concerning the viewing angles is presented.
71 citations
1 Nov 1982
TL;DR: Fit and Iterative Reconstruction (FAIR) as mentioned in this paper incorporates a priori knowledge of the approximate functional form of the source, and the parameters of this functional model are determined from the available projection data by a weighted fitting procedure.
Abstract: Projection data that are limited in number and range of viewing angle cannot completely specify an arbitrary source function. In the space of all permissible functions there exists a null subspace about which the projection measurements provide no information. Deterministic reconstruction algorithms usually set the null space contributions to zero leading to severe reconstruction artifacts. A Fit And Iterative Reconstruction (FAIR) method is proposed that incorporates a priori knowledge of the approximate functional form of the source. In FAIR the parameters of this functional model are determined from the available projection data by a weighted fitting procedure. The resulting distribution is then iteratively revised to bring the final estimate into agreement with the measured projections using a standard algorithm such as ART.
17 citations
TL;DR: Distant visual acuity was determined for several viewing angles in two restrained White Carneaux pigeons, suggesting that foveal viewing is relatively less advantageous for acuity in pigeons than in humans.
17 citations
Patent•
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19 Apr 1982
TL;DR: In this paper, a track system is used to ensure that the top portion of each carpet sample is held at the desired viewing angle to allow a better view of the carpet sample.
Abstract: Carpet display rack which allows even spacing and easy removal of carpet samples which have the top portion thereof angled to allow a better viewing of the sample. The carpet display rack has a novel track system which ensures that the top of each carpet sample is held at the desired viewing angle.
6 citations
Patent•
25 Sep 1982
TL;DR: In this paper, an arithmetic circuit within a damping circuit 130 calculates positions (x and (y) of the working point O of a robot by means of the arm length l and angle psi of the robot.
Abstract: PURPOSE:To make adjustment to the focus and the viewing angle automatically, by calculating the working position of a robot and always turning an ITV camera to the working point. CONSTITUTION:An arithmetic circuit within a damping circuit 130 calculates positions (x) and (y) of the working point O of a robot by means of the arm length l and angle psi of the robot. Then the viewing direction alpha of a ITV camera consisting of left and right ITV cameras 110a and 110b is calculated along with the viewing angle theta of the left and right ITV cameras. Based on the results of these calculations, the ITV camera is turned to the point O and controlled. At the same time, the distance between the ITV camera and the point O is calculated to perform an automatic control of focus. Thus the ITV camera is always turned to the working point to make automatic adjustment to both the focus and the viewing angle.
4 citations
TL;DR: In this paper, a new standard pencil task is proposed, which is a penciled circle on a perfectly diffuse white background, which permits the construction of a visual CRF gauge which is inexpensive, stable, portable and direct reading, and which works equally for polarized and unpolarized light and for virtually any viewing angle.
Abstract: A new standard pencil task is proposed. This is a penciled circle on a perfectly diffuse white background. It permits the construction of a visual CRF gauge which is inexpensive, stable, portable and direct-reading, and which works equally for polarized and unpolarized light and for virtually any viewing angle. In addition, the proposed new standard task has advantages both for prediction and for lighting design.
2 citations
TL;DR: The results show that the proposed method can provide acceptable images from data collected at scanning speeds that would otherwise produce severely blurred images by conventional methods.
Abstract: A method is proposed to reduce the requirement on the scanning speed for dynamic computed tomography of relatively fast moving objects such as the heart. From the projections measured at different times, a set of optimal projections is computed for reconstructing the image at any specified time within a permissible interval. In the method, the corresponding characteristic features of the measured projections at the same viewing angle are matched optimally by a nonlinear transformation. The matched projections are then used in an interpolation procedure to compute the projections required at the specified time. The method has been tested with mathematical phantoms that undergo partial expansion, contraction, and translational motion. The results show that the proposed method can provide acceptable images from data collected at scanning speeds that would otherwise produce severely blurred images by conventional methods.
2 citations
Patent•
21 May 1982
TL;DR: In this paper, a display element 1 shows extremely strong display contrast in the direction of 3 and its display is invisible despite the observation from the directions other than this, while display elements 2 show extremely strong contrast in direction of 4, and their display is visible despite the observations from the direction other than 4, where 3 and 4 are respectively the direction where there is the right eye of an observer and his left eye.
Abstract: PURPOSE:To suppress the flickering of display images by forming display elements of strong viewing angle dependency having viewing angles in different directions into two layers. CONSTITUTION:A display element 1 shows extremely strong display contrast in the direction of 3 and its display is invisible despite the observation from the directions other than this. A display element 2 shows extremely strong contrast in the direction of 4, and its display is invisible despite the observation from the direction other than this. The directions of 3 and 4 are respectively the direction where there is the right eye of an observer and the direction where there is his left eye. This results in that the observer is viewing an actual object, thus he is able to observe a natural stereoscopic image free from longitudinal stripes and flickering.
2 citations