Visibility Judgment Research Articles

Visibility analysis by light attenuation ratio recorded with portable camera at the full-scale hot smoke test site

Some countries have enacted the full-scale hot smoke test standards to verify the effectiveness of smoke extraction systems. Unfortunately, the judgment of most performed tests is based on vision and lacks scientific value. It is important to establish a scientific and quantifiable measurement system for visibility judgment in a large space. This paper analyzed the visibility values obtained through the light attenuation in a full-scale hot smoke test site. The quadratic regression relationships between the gray scale values and the attenuation ratios were derived. The visibility of the test site can be also obtained by grayscale analysis of recorded images. A qualified emergency direction light was used as a light source, and a closed-circuit television and a portable camera were adopted for image recording. These images were converted into grayscale pictures to obtain the gray scale values at the center of the bright spot. By comparing with the light attenuation ratio of the quantifiable measurement equipment in front of the light source, the results showed excellent relevance and demonstrated the applicability of the captured images.

Probing doors to visual awareness: Choice set, visibility, and confidence

ABSTRACT Visibility and confidence are two subtly (sensation-based and intuition-based) different ways to assess our visual experiences. We investigated how different choice sets affect the ability of confidence and visibility judgments to retrieve conscious information from perceptual decision-making processes. Six participants made introspective judgments on sinusoidal gratings at close to chance signal-to-noise values. We used signal detection theory and mixed regression models to analyze choices and pupilometric recordings. The results suggest that allowing null responses (e.g., “I saw nothing”) asymmetrically affects the signal distribution variances associated with null and non-null responses; confidence is more effective than visibility in accessing unconscious information; and bias-free methods hinder accurate introspective judgment by forbidding free decision criteria. Our findings underscore the importance of the context afforded by choice and stimulus sets, which determines the extent to which elicited introspective judgments are based on the actual information from the past events they are intended to measure.

Spontaneous alpha-band amplitude predicts subjective visibility but not discrimination accuracy during high-level perception

Near-threshold perception is a paradigm case of awareness diverging from reality – the perception of an unchanging stimulus can vacillate from undetected to clearly perceived. The amplitude of low-frequency brain oscillations - particularly in the alpha-band (8–13 Hz) - has emerged as a reliable predictor of trial-to-trial variability in perceptual decisions based on simple, low-level stimuli. Here, we addressed the question of how spontaneous oscillatory amplitude impacts subjective and objective aspects of perception using high-level visual stimuli. Human observers completed a near-threshold face/house discrimination task with subjective visibility ratings while electroencephalograms (EEG) were recorded. Using single-trial multiple regression analysis, we found that spontaneous fluctuations in prestimulus alpha-band amplitude were negatively related to visibility judgments but did not predict trial-by-trial accuracy. These results extend previous findings that indicate that strong prestimulus alpha diminishes subjective perception without affecting the accuracy or sensitivity (d’) of perceptual decisions into the domain of high-level perception.

Three-Dimensional Visualization Analysis of Distributed Virtual Reality Taking into Account Grid Scientific Computing Model

With the in-depth development of the application of virtual reality technology, people have higher and higher requirements for the complexity and realism of virtual scene, which far exceeds the real-time processing ability of computer graphics hardware. Back to this, there is an urgent need to solve the contradiction between the complexity of the scene and the real-time interaction. In this paper, the real-time visualization of real-time distributed virtual reality is studied in many aspects. Starting with the analysis of the characteristics of real-time visualization technology of distributed virtual reality, this paper studies the system structure of real-time distributed virtual reality, puts forward the idea of realizing real-time distributed virtual reality visualization, introduces grid scientific computing model, and constructs a three-dimensional vertical visualization platform of distributed virtual reality. The visual analysis of virtual reality is carried out for the corresponding slope and corresponding geological conditions; the comprehensive analysis of spatial distribution is carried out by using three-dimensional visualization, the relevant contents of real-time display, and the generation and real-time display of realistic graphics. In order to increase the realism of 3D image, visibility judgment, and blanking technology, the level of detail model and texture mapping is used. The simulation results show that the grid scientific computing model is effective and can support the three-dimensional visual analysis of distributed virtual reality.

Effects of non-invasive brain stimulation on visual perspective taking: A meta-analytic study

Visual perspective taking (VPT) is a critical ability required by complex social interaction. Non-invasive brain stimulation (NIBS) has been increasingly used to examine the causal relationship between brain activity and VPT, yet with heterogeneous results. In the current study, we conducted two meta-analyses to examine the effects of NIBS of the right temporoparietal junction (rTPJ) or dorsomedial prefrontal cortex (dmPFC) on VPT, respectively. We performed a comprehensive literature search to identify qualified studies and computed the standardized effect size (ES) for each combination of VPT level (Level-1: visibility judgment; Level-2: mental rotation) and perspective (self and other). Thirteen studies (rTPJ: 12 studies, 23 ESs; dmPFC: 4 studies, 14 ESs) were included in the meta-analyses. Random-effects models were used to generate the overall effects. Subgroup analyses for distinct VPT conditions were also performed. We found that rTPJ stimulation significantly improved participants' visibility judgment from the allocentric perspective, whereas its effects on other VPT conditions are negligible. Stimulation of dmPFC appeared to influence Level-1 performance from the egocentric perspective, although this finding was only based on a small number of studies. Notably, contrary to some theoretical models, we did not find strong evidence that these regions are involved in Level-2 VPT with a higher requirement of mental rotation. These findings not only advance our understanding of the causal roles of the rTPJ and dmPFC in VPT, but also reveal that the efficacy of NIBS on VPT is relatively small. Additionally, researchers should also be cautious about the potential publication bias and selective reporting.

Modelling visibility judgments using models of decision confidence

How can we explain the regularities in subjective reports of human observers about their subjective visual experience of a stimulus? The present study tests whether a recent model of confidence in perceptual decisions, the weighted evidence and visibility model, can be generalized from confidence to subjective visibility. In a postmasked orientation identification task, observers reported the subjective visibility of the stimulus after each single identification response. Cognitive modelling revealed that the weighted evidence and visibility model provided a superior fit to the data compared with the standard signal detection model, the signal detection model with unsystematic noise superimposed on ratings, the postdecisional accumulation model, the two-channel model, the response-congruent evidence model, the two-dimensional Bayesian model, and the constant noise and decay model. A comparison between subjective visibility and decisional confidence revealed that visibility relied more on the strength of sensory evidence about features of the stimulus irrelevant to the identification judgment and less on evidence for the identification judgment. It is argued that at least two types of evidence are required to account for subjective visibility, one related to the identification judgment, and one related to the strength of stimulation.

New modeling method of millimeter-wave radar considering target radar echo intensity

Virtual test evaluation is an important development direction for automatic driving technology testing and evaluation. The millimeter-wave radar sensor model used in virtual test evaluation should meet the real-time and accuracy requirements of the system. The current millimeter-wave radar model can satisfy real-time requirements but cannot simulate the physical characteristics of millimeter-wave radar. This study proposes a millimeter-wave radar model, which introduces the radar cross-sectional (RCS) area judgment index based on geometric clipping extraction and target visibility judgment. Through simulation verification of target visibility, the millimeter-wave radar model integrated with RCS indicators has demonstrated consistent test results with real millimeter-wave radar. The millimeter-wave radar model can better simulate the physical characteristics and error conditions of real millimeter-wave radar as well as enhance the accuracy of virtual simulation tests and evaluation of automatic driving while ensuring the real-time requirements of the simulation.

In search of the optimal measure of awareness: Discrete or continuous?

Studies of perceptual awareness require sensitive measures reflecting subjective judgments of visibility. Two scales have been proposed for this purpose: the Continuous Scale (CS) and the Perceptual Awareness Scale (PAS). Here we compare the scales in the context of the Gabor patch orientation discrimination task and propose a Continuous Perceptual Awareness Scale (C-PAS) that aims to combine their advantages. The results of the study shown no differences in sensitivity between the scales. However, we observed differences between the scales in awareness ratings frequencies and accuracy associated with the lowest ratings. We concluded that visibility ratings are often biased, and thus, the scale sensitivity may not be optimal. Furthermore, based on the additional analyses, we argued that there is an advantage of using C-PAS over CS. The scale allows to use an additional variability of judgment within PAS categories and thus it may enable more fine-grained measurement of visibility at near-threshold conditions.

Error-related cardiac response as information for visibility judgements

Interoception provides information about the saliency of external or internal sensory events and thus may inform perceptual decision-making. Error in performance is an example of a motivationally significant internal event that evokes autonomic nervous system response resembling the orienting response: heart rate deceleration, increased skin conductance response, and pupil dilation. Here, we investigate whether error-related cardiac activity may serve as a source of information when making metacognitive judgments in an orientation discrimination backward masking task. In the first experiment, we found that the heart accelerates less after an incorrect stimuli discrimination than after a correct one. Moreover, this difference becomes more pronounced with increasing subjective visibility of the stimuli. In the second experiment, this accuracy-dependent pattern of cardiac activity was found only when participants listened to their own heartbeats, but not someone else’s. We propose that decision accuracy coded in cardiac activity may be fed as a cue to subjective visibility judgments.

Accelerating geospatial analysis on GPUs using CUDA

Inverse distance weighting (IDW) interpolation and viewshed are two popular algorithms for geospatial analysis. IDW interpolation assigns geographical values to unknown spatial points using values from a usually scattered set of known points, and viewshed identifies the cells in a spatial raster that can be seen by observers. Although the implementations of both algorithms are available for different scales of input data, the computation for a large-scale domain requires a mass amount of cycles, which limits their usage. Due to the growing popularity of the graphics processing unit (GPU) for general purpose applications, we aim to accelerate geospatial analysis via a GPU based parallel computing approach. In this paper, we propose a generic methodological framework for geospatial analysis based on GPU and its programming model Compute Unified Device Architecture (CUDA), and explore how to map the inherent parallelism degrees of IDW interpolation and viewshed to the framework, which gives rise to a high computational throughput. The CUDA-based implementations of IDW interpolation and viewshed indicate that the architecture of GPU is suitable for parallelizing the algorithms of geospatial analysis. Experimental results show that the CUDA-based implementations running on GPU can lead to dataset dependent speedups in the range of 13–33-fold for IDW interpolation and 28–925-fold for viewshed analysis. Their computation time can be reduced by an order of magnitude compared to classical sequential versions, without losing the accuracy of interpolation and visibility judgment.

A fast and effective approach to generate true orthophoto in built‐up area

PurposeOrthophoto suffers from the relief displacement effects magnified by high resolution imaging sensors especially when mapping urban areas. True orthophotos eliminating relief displacement with digital surface model (DSM) are presented to assure reliable interpretability and maintain the high quality of the available data. Previous efforts did not provide accurate and fast ways for generating true othorphoto. The purpose of this paper is to try to solve the problem by analyzing the complexity of algorithm processes and finding the optimum manner to allocate them.Design/methodology/approachIn this paper, an optimum segmentation number for radial sweep is presented to achieve minimum complexity. First, the scan area, number of azimuth lines and visibility judgment area of radial sweep and spiral sweep method have been discussed with rigorous geometric theory, and then algorithm complexities of both methods are estimated with mathematical computation theory. Finally, minimum complexity of the methods is obtained with extreme point theory of differential calculus.FindingsExperiments have demonstrated that the proposed method has the best efficiency, and is efficient to avoid “M‐potion” problem, and false occlusions and false visibilities caused by the rolling area, the incompatibility between the DSM and ground image resolution.Originality/valueThe deduction and experiments indicate that the proposed method is a robust, accurate, fast, and effective approach to generate high quality, true orthophoto at a large‐scale.

Two kinds of visual perspective taking

Visual perspective taking can be used to determine where objects are located relative toanother agent, or whether the agent can see a particular object. Four experiments indicated that different processes provide these different kinds of information. When participants were asked to report whether an object was to the left or to the right of another agent, response times (RTs) increased with increasing angular distance between the participant and the agent, suggesting that participants mentally transformed their perspective to align it with that of the agent. For visibility judgments, RTs were independent of the angle between the participant and the agent but increased with the distance between the agent and the object, suggesting that participants traced the agent's line of sight. Together, these data suggest that perspective taking encompasses at least two qualitatively different computational processes: one that updates the viewer's imagined perspective, and one that traces a line of sight.

The Relationship between Judged Visibility and Judged Air Quality: Results of a Survey

Visibility and air quality are usually treated as separate issues since they are governed by somewhat different sets of processes. When people judge air however, they must be influenced by visibility. Despite this, visibility and general air quality have not been studied together in surveys or experiments with human observers. The recent work on visibility has concentrated on visual air quality, neglecting more general air quality The work on judgments of general air quality has neglected separate judgments of visiThe study reported here was performed, in part, to determine the extent to which peoples' judgments of air quality are related to their judgments of visibility. The study was also performed, in part, to determine the extent to which people's judgments of visibility and overall air quality are related to their expectations, to the importance they attach to air and to their experience with various degrees of air quality.