Photorealistic Images Research Articles

Detection of vehicle approach in the presence of additional motion and simulated observer motion at road junctions.

One of the key contributory factors for accident involvement is the misjudgment of vehicle approach. Past research has indicated that individuals can use the rate of visual "looming" in order to judge the time to arrival (TTA) of approaching vehicles. Although a large number of road traffic collisions occur at roadside junctions, very little research has focused on individuals' abilities to detect the onset of visual looming within a complex road scene at junction scenarios. In this research, computer generated scenes with photorealistic vehicle images, and a psychophysical staircase methodology, were used to explore drivers' ability to detect the approach of both motorcycles and cars within a contextually rich city scene. Across three experiments the effect of additional vehicular and observer motion on driver detection of vehicle approach was assessed. Results showed that individuals were significantly poorer at detecting the approach of the motorcycle stimulus compared with the car stimulus. Results also showed that additional vehicular motion within the scene had a negative effect on detection thresholds for the car stimulus. Finally, the results showed that introducing lateral global motion of the scene, such as might occur if the observer was moving steadily forward from a junction, negatively affected detection thresholds. The theoretical implications of the findings are discussed, including how vehicles traveling at high speed are often below the threshold for detecting visual looming. Practical implications for road design and layout are discussed that address the perceptual errors noted.

A Novel Face Hallucination with an Error Regression Model and MPCA in RGB Color Space

This paper proposes a novel face super-resolution reconstruction (hallucination) technique, color face images reconstruction of RGB space with an error regression model in multi-linear principal component analysis (MPCA). From hallucination framework, many color face images are explained in RGB space. Then, they can be naturally described as tensors or multi-linear arrays. In this way, the error regression analysis is used to find the error estimation which can be obtained from the existi ng LR in tensor space. The framework consists of learning and hallucinating process. In learning process is from the mistakes in reconstruct face images of the training dataset by MPCA, then finding the relationship between input and error by regression analysis. In hallucinating process uses normal method by back-projection of MPCA, after that the result is corrected with the error estimation. In this contribution we show that our hallucination technique can be suitable for color face images both in RGB space. By using the MPCA subspace with error regression model, we can generate photorealistic color face images. Our approach is demonstrated by extensive experiments with high-quality hallucinated color faces. In addition, our experiments on face images from FERET database validate our algorithm

Photorealistic ray tracing of free-space invisibility cloaks made of uniaxial dielectrics

The design rules of transformation optics generally lead to spatially inhomogeneous and anisotropic impedance-matched magneto-dielectric material distributions for, e.g., free-space invisibility cloaks. Recently, simplified anisotropic non-magnetic free-space cloaks made of a locally uniaxial dielectric material (calcite) have been realized experimentally. In a two-dimensional setting and for in-plane polarized light propagating in this plane, the cloaking performance can still be perfect for light rays. However, for general views in three dimensions, various imperfections are expected. In this paper, we study two different purely dielectric uniaxial cylindrical free-space cloaks. For one, the optic axis is along the radial direction, for the other one it is along the azimuthal direction. The azimuthal uniaxial cloak has not been suggested previously to the best of our knowledge. We visualize the cloaking performance of both by calculating photorealistic images rendered by ray tracing. Following and complementing our previous ray-tracing work, we use an equation of motion directly derived from Fermat's principle. The rendered images generally exhibit significant imperfections. This includes the obvious fact that cloaking does not work at all for horizontal or for ordinary linear polarization of light. Moreover, more subtle effects occur such as viewing-angle-dependent aberrations. However, we still find amazingly good cloaking performance for the purely dielectric azimuthal uniaxial cloak.

Quantifying the effects of harvest block design on aesthetic preferences

In visually sensitive areas, planners use a variety of techniques to mitigate the visible effects of harvesting, including creating designs that appear more natural and less blocky. However, little empirical evidence exists about the degree to which these shapes influence preferences. We aim to fill this gap by investigating the perceptual effects of three shape characteristics: geometric primitive (circle, square, triangle, and trapezoid), complexity, and aspect ratio. Fifty-two photo-realistic images were rendered of a forest scene with a single harvest on a hillside. Forty individuals rated each image. The results indicate that geometric primitive had the largest effect on preference for harvest design of the three variables tested followed very closely by complexity. Yet, the most intriguing finding was the interaction of these two variables. In general, an increase in complexity for square and circular shapes caused higher preference ratings, while for trapezoid and triangle, this was only true as complexity progressed from low to moderate levels. The relationship between preference rating and complexity was nonlinear; the largest improvement existed at the moderate level of complexity. Operationally, this demonstrates that rounded-edged circular shapes are the most preferable but that even with a moderate level of complexity, preferences increase dramatically.

Reconstructing palaeo-volcanic geometries using a Geodynamic Regression Model (GRM): Application to Deception Island volcano (South Shetland Islands, Antarctica)

This article describes a reconstruction made of the palaeo-volcanic edifice on Deception Island (South Shetland Islands, Antarctica) prior to the formation of its present caldera. Deception Island is an active Quaternary volcano located in the Bransfield Strait, between the South Shetland Islands and the Antarctic Peninsula. The morphology of the island has been influenced mainly by the volcanic activity but geodynamics and volcanic deformation have also contributed. A volcanic reconstruction method, the Geodynamic Regression Model (GRM), which includes a terrain deformation factor, is proposed. In the case of Deception Island, the directions of this deformation are NW–SE and NE–SW, and match both the observed deformation of the Bransfield Strait and the volcanic deformation monitored over the last 20years in the island, using Global Navigation Satellite System (GNSS) techniques. Based on these data, possible volcanic deformation values of 5–15mm/yr in these directions have been derived. A possible coastline derived from a current bathymetry is transformed, according to values for the chosen date, to obtain the palaeo-coastline of Deception Island of 100kyears ago. Topographic, geomorphologic, volcanological and geological data in a GIS system have been considered, for computation of the outside caldera slope, palaeo-coastline, palaeo-summit height and palaeo digital elevation model (DEM). The result is a 3D palaeo-geomorphological surface model of a volcano, reaching 640m in height, with an increase of 4km3 in volume compared to the current edifice, covering 4km2 more surface area and the method reveals the previous existence of parasite volcanoes. Two photorealistic images of the island are obtained by superposition of textures extracted from a current Quick Bird satellite image also. This technique for reconstructing the terrain of an existing volcano could be useful for analysing the past and future geomorphology of this island and similar locations.

Reducing Render Time in Ray Tracing by Pixel Averaging

Many computer graphics rendering algorithms and techniques use ray tracing for generatingnatural and photo-realistic images. Ray tracing is a method to convert 3D-modeles into 2D-high quality images by complex computation. The millions of rays must be simulated and traced to create realistic image. A method for reducing render time is acceleration structures. The kd -tree is the most commonly used in accelerating ray tracing algorithms. This paper has focused on reducing render time. We propose tow methods that are combined with ray tracing method for obtaining some pixel colour of image plane . Our methods are linear algorithm and arefaster than ray tracing method. Our results show that our methods are at least 50% faster than spatial median approach for reasonably complex scenes with around 70k polygons and about 0.2% quality degradation. In this article, we show that these proposal methods canbe combined with other ray tracing methodssuch as SAH to reduce render time.

Sketch-based aesthetic product form exploration from existing images using piecewise clothoid curves

We present a new sketch-based product form exploration technique that works from images and sketches of existing products. At the heart of our approach, is a multi-stroke curve beautification method and a curve-based image deformation algorithm. The proposed approach converts groups of strokes into piecewise clothoid curves in order to produce visually pleasing shapes. The deformation diffusion algorithm then spatially distributes the user specified deformations through out the image to produce smooth transformations from the original image to the resulting image. We demonstrate the technique on a variety of images including photo-realistic images, real product images, and sketches.

K-clustered tensor approximation

With the increasing demands for photo-realistic image synthesis in real time, we propose a sparse multilinear model, which is named K-Clustered Tensor Approximation (K-CTA), to efficiently analyze and approximate large-scale multidimensional visual datasets, so that both storage space and rendering time are substantially reduced. K-CTA not only extends previous work on Clustered Tensor Approximation (CTA) to exploit inter-cluster coherence, but also allows a compact and sparse representation for high-dimensional datasets with just a few low-order factors and reduced multidimensional cluster core tensors. Thus, K-CTA can be regarded as a sparse extension of CTA and a multilinear generalization of sparse representation. Experimental results demonstrate that K-CTA can accurately approximate spatially varying visual datasets, such as bidirectional texture functions, view-dependent occlusion texture functions, and biscale radiance transfer functions for efficient rendering in real-time applications.

Visual “Literacy” in the Digital Age

This essay is a reflection on the ways in which visual media have evolved since the 1994 publication of the author's book Visual “Literacy”: Image, Mind, and Reality. The essay focuses on two major technological changes in visual media, and on the cultural transformations that have accompanied those changes. The first technological change is the development of increasingly powerful techniques for the digital manipulation of photographs and the creation of computer-generated photorealistic images. Reviewing this development, which has made the task of detecting visual fraud more challenging, the essay assesses the likelihood that it may also have brought about an enhancement in societal levels of visual “literacy.” Such an enhancement may also be a by-product of the second technological change discussed in this essay, namely, the increasing availability of digital networks for the dissemination of images and for public commentary about those images. The essay examines the use of such commentary for questioning the authenticity of visual advocacy and for exposing digital fraud.

Keynote Speaker: Taking the "Virtual" Out of Virtual Reality

Summary form only given. Today's graphics programs cannot only produce stunning photo-realistic images or convincingly real scene displays for interactive exploration, they can also produce physi cal output - thanks to the emergence of several different layered manufacturing technologies. For many design activities creating tangible models through some rapid prototyping prcess is a new and crucial feedback loop for debugging the functionality or customer-appeal of a new product. Dr. Sequin has two decades of experience with creating mathematical visualization models and designs ranging from university buildings to abstract geometrical sculptures. Turning these virtual creations into physical realities, however, raises a whole new set of issues that are often overlooked in the initial virtual design phase.

Goal-Side Selection in Soccer Penalty Kicking When Viewing Natural Scenes

The present study investigates the influence of goalkeeper displacement on goal-side selection in soccer penalty kicking. Facing a penalty situation, participants viewed photo-realistic images of a goalkeeper and a soccer goal. In the action selection task, they were asked to kick to the greater goal-side, and in the perception task, they indicated the position of the goalkeeper on the goal line. To this end, the goalkeeper was depicted in a regular goalkeeping posture, standing either in the exact middle of the goal or being displaced at different distances to the left or right of the goal’s center. Results showed that the goalkeeper’s position on the goal line systematically affected goal-side selection, even when participants were not aware of the displacement. These findings provide further support for the notion that the implicit processing of the stimulus layout in natural scenes can effect action selection in complex environments, such in soccer penalty shooting.

Development of Visualization Tools for Large-scale Geoscience Simulations

In this paper, the developments of visualization tools for large-scale geoscience simulations (e.g. Earth quakes, Tsunami and Typhoon simulations) using such as K-computer are presented. We first describe the development of the middleware to deal with the expensive rendering cost for the huge simulation data on a PC-cluster system. Our method combined with ray-tracing calculations provides a quality of photorealistic image to scientific visualization with a reasonable rendering time. We also implement a co-processing mode that can mimic an in-situ visualization process which may be the most effective method to reduce the time and storage space required for the visualization process. Then we discuss the new approach of the in-situ visualization method with petascale data. We propose to use bullet-time technique in the in-suite visualizations process, which generates many images/movies with arbitrary selected visualization parameters for a snapshot/sequential data. In order to deal with the visualization results brought by this method, we develop application software to play animation movies which can change the files on screen interactively in a real time. Finally we introduce the development of the application software “EXTRAWING” which visualize simulation result on Google Earth, as a powerful presentation tool of the simulation result.

A Geometry-Bias-Based Reconstruction of Global Photon Maps

Photon mapping can efficiently render high-quality photorealistic images with full global illumination. It stores many photons in photon map for improving reconstruction qualities of complex illumination, which leads to high memory overhead and long reconstruction time. This paper presents a geometry-biasbased reconstruction of global photon maps. We divide the bounding box of photons into a number of grids. Based on the number of photons and the curvature variation of surface in every non-empty grid, we take a fraction of photons in grid to reconstruct global photon map, and ensure conservation of total energy of photons in grid before and after reconstruction. Our method has low computation cost and keeps view-independence of photon map. The experiments show that the differences of reconstructed illumination effects between two photon maps are very small even if the photon number of photon map before reconstruction is 20 times the one after reconstruction. Compared with the non-reconstructed photon map with the same number of photons, the reconstructed photon map has far better reconstructed illumination effect, and can effectively reduce illumination error due to all kinds of geometry biases.

Raytraced images for testing the reconstruction of fibre orientation distributions

The orientation distribution of fibres is relevant to the properties of a number of different kinds of fibrous materials from many fields like biology and engineering, including short fibre reinforced composites. The Persistence of Vision Raytracer (PoV-Ray) is a program for creating photorealistic images using raytracing. We discuss a sort of creative misuse of this program in science, because it was originally developed as an artistic software. However, the ability to create virtual images of virtual parts, test the image recognition software that is used to measure the fibre orientation distribution, and compare the results with the known distibution is a huge step forward. In this article the focus is on slicing/photometry, but computed-tomography-like images or microscope images could be produced as well and used to test segmentation and skeletonization algorithms.

Developmental trends in detection threshold for looming objects

Detection and sensitivity to optical expansion is critical for collision avoidance and survival. Adult sensitivity to looming and motion in depth has been well documented under strict psychophysical conditions (e.g., Regan & Beverley, 1979). Much less is known about perceptual thresholds for looming in complex scenes, and there has been no investigation of developmental decrements in perceptual ability, which may explain in part children's overrepresentation in road traffic casualties. Looming thresholds for children (n = 111) and adults (n = 27) were measured using adaptive (best-PEST) psychophysical procedures to determine sensitivity to looming in foveal or extra-foveal vision (4.25° eccentricity). A photo-realistic image of a car was viewed monocularly against a static road scene background for 200 ms. Observers were required to determine whether the car expanded or not. The car image changed in size and virtual distance to simulate approach at different speeds, with time-to-passage fixed at 5s (sufficient time to cross the road). Images were automatically rescaled according to viewing distance so that visual angles were equivalent to those experienced at the roadside. Results show clear developmental trends in looming thresholds. Younger children (6–9 yrs) were less sensitive to optical expansion than older children (10–11 yrs) and adults when the image expanded isotropically in foveal or extra-foveal vision, and as well as when it expanded with additional lateral image translation (1° scene displacement scaled with distance) in foveal vision, but not extra-foveal vision. Conversion of looming thresholds into vehicle speeds revealed that children are unable to reliably detect cars approaching 5 s away at speeds in excess of 25 mph if they do not fixate directly on the car, or are in motion when looking down the road. Our study is the first to provide evidence that the neural mechanisms for detection of looming are not fully developed until adulthood.

Perceptual discrimination of computer generated and photographic faces

Modern day computer graphics are capable of generating highly photorealistic images resulting in challenging legal situations. For example, as a result of a 2002 U.S. Supreme Court ruling, computer generated child pornography is protected speech, while pornographic photographs depicting an actual child remains illegal. The ability to distinguish between protected and illegal material assumes that law enforcement agents, attorneys, jurors, and judges can reliably distinguish between computer generated and photographic imagery. We describe a series of psychophysical experiments that used images of varying resolution, JPEG compression, and color to explore the ability of observers to distinguish computer generated from photographic images of people. The results allow us to assign a probability that an image that is judged to be a photograph is, in fact, a photograph.

Adaptation and the perception of facial age

We examined how the perceived age of adult faces is affected by adaptation to younger or older adult faces. Observers viewed images of a synthetic male face simulating ageing over a modelled range from 15 to 65 years. Age was varied by changing shape cues or textural cues. Age level was varied in a staircase to find the observer's subjective category boundary between “old” and “young”. These boundaries were strongly biased by adaptation to the young or old face, with significant aftereffects induced by either shape or textural cues. A further experiment demonstrated comparable aftereffects for photorealistic images of average older or younger adult faces, and found that aftereffects showed some selectivity for a change in gender but also strongly transferred across gender. This transfer shows that adaptation can adjust to the attribute of age somewhat independently of other facial attributes. These findings suggest that perceived age, like many other natural facial dimensions, is highly susceptible to adaptation, and that this adaptation can be carried by both the structural and textural changes that normally accompany facial ageing.

Efficient Depth‐of‐Field Rendering with Adaptive Sampling and Multiscale Reconstruction

AbstractDepth‐of‐field is one of the most crucial rendering effects for synthesizing photorealistic images. Unfortunately, this effect is also extremely costly. It can take hundreds to thousands of samples to achieve noise‐free results using Monte Carlo integration. This paper introduces an efficient adaptive depth‐of‐field rendering algorithm that achieves noise‐free results using significantly fewer samples. Our algorithm consists of two main phases: adaptive sampling and image reconstruction. In the adaptive sampling phase, the adaptive sample density is determined by a ‘blur‐size’ map and ‘pixel‐variance’ map computed in the initialization. In the image reconstruction phase, based on the blur‐size map, we use a novel multiscale reconstruction filter to dramatically reduce the noise in the defocused areas where the sampled radiance has high variance. Because of the efficiency of this new filter, only a few samples are required. With the combination of the adaptive sampler and the multiscale filter, our algorithm renders near‐reference quality depth‐of‐field images with significantly fewer samples than previous techniques.

Brain-bending art: Virtual reality, the old way

Trompe l'oeil painting has been around since ancient Greek and Roman times, but there's a lot more to it than just photorealistic images

Photorealism aftereffect

This study reports a novel visual aftereffect for photorealism judgments. Participants observed image sequences where a photograph was gradually transformed into an artificial image (a painting or a sketch). Their task was to choose the image that was the category boundary between the photograph and the artificial image among the frames of each image sequence. This task was performed before and after observing photographs or artificial images for 1min. The chosen images were less photorealistic after the observation of artificial images, suggesting an aftereffect for photorealism judgments. However, observation of photographs did not induce an aftereffect. It is known that the observation of the norms for perceptual judgments (e.g., the prototypical face for facial judgments) does not induce aftereffects. Thus, these results suggest that photorealistic images serve as the norm for the perceptual judgment of photorealism. The human visual system may represent the photorealism of artificial images as a deviation from photorealistic images.