Vision-based vanishing point detection of autonomous navigation of mobile robot for outdoor applications

The vision-based approach to mobile robot navigation is considered superior due to its affordability. This paper aims to design and construct an autonomous mobile robot with a vision-based system for outdoor navigation. This robot receives inputs from camera and ultrasonic sensor. The camera is used to detect vanishing points and obstacles from the road. The vanishing point is used to detect the heading of the road. Lines are extracted from the environment using a canny edge detector and Houghline Transforms from OpenCV to navigate the system. Then, removed lines are processed to locate the vanishing point and the road angle. A low pass filter is then applied to detect a vanishing point better. The robot is tested to run in several outdoor conditions such as asphalt roads and pedestrian roads to follow the detected vanishing point. By implementing a Simple Blob Detector from OpenCV and ultrasonic sensor module, the obstacle's position in front of the robot is detected. The test results show that the robot can avoid obstacles while following the heading of the road in outdoor environments. Vision-based vanishing point detection is successfully applied for outdoor applications of autonomous mobile robot navigation.

Perspective, the Visible and the Invisible in Chinese Paintings: A Response to Jean-Luc Marion

In the Chinese translation of The Crossing of the Visible, French phenomenologist Jean-Luc Marion, raised a question about the nature of Chinese paintings: does the relationship between the visible and the invisible commonly found in the Western painting play the same role in Chinese paintings? This essay aims to answer this question. Chinese paintings maintain the acceptance that the sense of perspective is the implementation of the invisible by the varieties of perspective, the invisible vanishing point and the poem. My response to Marion’s call opens a fresh dialogue between the French thought and the Chinese thought.

Existential Definition at the End of the American Road

This article discusses three films that helped landmark American cinema in the 1970s. Although differing in inception and reception, all three belong loosely to the genre of the road movie and are linked by protagonists whose stances of rebellion and alienation were characteristic of the counterculture of the 1970s and by the broader theme of existential self-definition that still influences moviemaking today. A critical and commercial failure on its release in 1970, Michelangelo Antonioni’s Zabriskie Point has been revalorized as an ambitious attempt to represent the political and cultural conflicts that seemed to be fracturing American society at the time. In contrast, Richard Sarafian’s Vanishing Point soon overcame the disadvantage of studio disinterest and established itself as a cult favorite. Arguably the definitive anti-hero of 1970s cinema, the amphetamine-fueled renegade driver played by Barry Newman achieves iconic stature through an act of defiant self-destruction that still leaves viewers of the film stunned. Finally, Clint Eastwood’s The Gauntlet, in which the actor-director breaks with his ‘Dirty Harry’ persona to depict a burned-out cop who redeems a ruined career, and enables himself a new start, not by making his own law but by enforcing the law on the books, and against all odds. In all three films, the still unspoiled landscape of the American Southwest, crisscrossed by its skein of highways, provides the tableau for escapist fantasies that may in fact be real, for high-speed chases and automotive acrobatics that defy the laws of physics, and for vignettes of an ‘outsider’ way of life that was already beginning to perish.

An Enhanced Pedestrian Visual-Inertial SLAM System Aided with Vanishing Point in Indoor Environments

The visual-inertial simultaneous localization and mapping (SLAM) is a feasible indoor positioning system that combines the visual SLAM with inertial navigation. There are accumulated drift errors in inertial navigation due to the state propagation and the bias of the inertial measurement unit (IMU) sensor. The visual-inertial SLAM can correct the drift errors via loop detection and local pose optimization. However, if the trajectory is not a closed loop, the drift error might not be significantly reduced. This paper presents a novel pedestrian dead reckoning (PDR)-aided visual-inertial SLAM, taking advantage of the enhanced vanishing point (VP) observation. The VP is integrated into the visual-inertial SLAM as an external observation without drift error to correct the system drift error. Additionally, the estimated trajectory’s scale is affected by the IMU measurement errors in visual-inertial SLAM. Pedestrian dead reckoning (PDR) velocity is employed to constrain the double integration result of acceleration measurement from the IMU. Furthermore, to enhance the proposed system’s robustness and the positioning accuracy, the local optimization based on the sliding window and the global optimization based on the segmentation window are proposed. A series of experiments are conducted using the public ADVIO dataset and a self-collected dataset to compare the proposed system with the visual-inertial SLAM. Finally, the results demonstrate that the proposed optimization method can effectively correct the accumulated drift error in the proposed visual-inertial SLAM system.

Geometric Constraints of Visual Space

Perspective space has been introduced as a computational model of visual space. The model is based on geometric features of visual space. The model has proven to describe a range of phenomena related to the visual perception of distance and size. Until now, the model lacks a mathematical description that holds for complete 3D space. Starting from a previously derived equation for perceived distance in the viewing direction, the suitability of various functions is analyzed. Functions must fulfill the requirement that straight lines, oriented in whatever direction in physical space, transfer to straight lines in visual space. A second requirement is that parallel lines oriented in depth in physical space, converge to a finite vanishing point in visual space. A rational function for perceived distance, compatible with the perspective-space model of visual space, satisfies the requirements. The function is unique. Analysis of alternative functions shows there is little tolerance for deviations. Conservation of the straightness of lines constrains visual space to having a single geometry. Visual space is described by an analytical function having one free parameter, that is, the distance of the vanishing point.

Viewing-patterns and perspectival painting: An eye-tracking study on the effect of the vanishing point

Linear perspective has long been used to create the illusion of three-dimensional space on the picture plane. One of its central axioms comes from Euclidean geometry and holds that all parallel lines converge in a single vanishing point. Although linear perspective provided the painter with a means to organize the painting, the question is whether the gaze of the beholder is also affected by the underlying structure of linear perspective: for instance, in such a way that the orthogonals leading to the vanishing point also automatically guides the beholder’s gaze. This was researched during a pilot study by means of an eye-tracking experiment at the Lab for Cognitive Research in Art History (CReA) of the University of Vienna. It appears that in some compositions the vanishing point attracts the view of the participant. This effect is more significant when the vanishing point coincides with the central vertical axis of the painting, but is even stronger when the vanishing point also coincides with a major visual feature such as an object or figure. The latter calls into question what exactly attracts the gaze of the viewer, i.e., what comes first: the geometrical construct of the vanishing point or the visual feature?