28 research outputs found
Playing for Data: Ground Truth from Computer Games
Recent progress in computer vision has been driven by high-capacity models
trained on large datasets. Unfortunately, creating large datasets with
pixel-level labels has been extremely costly due to the amount of human effort
required. In this paper, we present an approach to rapidly creating
pixel-accurate semantic label maps for images extracted from modern computer
games. Although the source code and the internal operation of commercial games
are inaccessible, we show that associations between image patches can be
reconstructed from the communication between the game and the graphics
hardware. This enables rapid propagation of semantic labels within and across
images synthesized by the game, with no access to the source code or the
content. We validate the presented approach by producing dense pixel-level
semantic annotations for 25 thousand images synthesized by a photorealistic
open-world computer game. Experiments on semantic segmentation datasets show
that using the acquired data to supplement real-world images significantly
increases accuracy and that the acquired data enables reducing the amount of
hand-labeled real-world data: models trained with game data and just 1/3 of the
CamVid training set outperform models trained on the complete CamVid training
set.Comment: Accepted to the 14th European Conference on Computer Vision (ECCV
2016
Real-time architecture for robust motion estimation under varying illumination conditions
Motion estimation from image sequences is a complex problem which requires high computing resources and is highly affected by changes in the illumination conditions in most of the existing approaches. In this contribution we present a high performance system that deals with this limitation. Robustness to varying illumination conditions is achieved by a novel technique that combines a gradient-based optical flow method with a non-parametric image transformation based on the Rank transform. The paper describes this method and quantitatively evaluates its robustness to different illumination changing patterns. This technique has been successfully implemented in a real-time system using reconfigurable hardware. Our contribution presents the computing architecture, including the resources consumption and the obtained performance. The final system is a real-time device capable to computing motion sequences in real-time even in conditions with significant illumination changes. The robustness of the proposed system facilitates its use in multiple potential application fields.This work has been supported by the grants DEPROVI (DPI2004-07032), DRIVSCO (IST-016276-2) and TIC2007:âPlataforma Sw-Hw para sistemas de visiĂłn 3D en tiempo realâ
Virtual Reality to Simulate Visual Tasks for Robotic Systems
Virtual reality (VR) can be used as a tool to analyze the interactions between the visual system
of a robotic agent and the environment, with the aim of designing the algorithms to solve the
visual tasks necessary to properly behave into the 3D world. The novelty of our approach lies
in the use of the VR as a tool to simulate the behavior of vision systems. The visual system of
a robot (e.g., an autonomous vehicle, an active vision system, or a driving assistance system)
and its interplay with the environment can be modeled through the geometrical relationships
between the virtual stereo cameras and the virtual 3D world. Differently from conventional
applications, where VR is used for the perceptual rendering of the visual information to a
human observer, in the proposed approach, a virtual world is rendered to simulate the actual
projections on the cameras of a robotic system. In this way, machine vision algorithms can be
quantitatively validated by using the ground truth data provided by the knowledge of both
the structure of the environment and the vision system
Performance Characterization of Watson Ahumada Motion Detector Using Random Dot Rotary Motion Stimuli
The performance of Watson & Ahumada's model of human visual motion sensing is compared against human psychophysical performance. The stimulus consists of random dots undergoing rotary motion, displayed in a circular annulus. The model matches psychophysical observer performance with respect to most parameters. It is able to replicate some key psychophysical findings such as invariance of observer performance to dot density in the display, and decrease of observer performance with frame duration of the display
Assessment and application of wavelet-based optical flow velocimetry (wOFV) to wall-bounded turbulent flows
The performance of a wavelet-based optical flow velocimetry (wOFV) algorithm
to extract high accuracy and high resolution velocity fields from particle
images in wall-bounded turbulent flows is assessed. wOFV is first evaluated
using synthetic particle images generated from a channel flow DNS of a
turbulent boundary layer. The sensitivity of wOFV to the regularization
parameter (lambda) is quantified and results are compared to PIV. Results on
synthetic particle images indicated different sensitivity to
under-regularization or over-regularization depending on which region of the
boundary layer is analyzed. Synthetic data revealed that wOFV can modestly
outperform PIV in vector accuracy across a broad lambda range. wOFV showed
clear advantages over PIV in resolving the viscous sublayer and obtaining
highly accurate estimates of the wall shear stress. wOFV was also applied to
experimental data of a developing turbulent boundary layer. Overall, wOFV
revealed good agreement with both PIV and PIV + PTV. However, wOFV was able to
successfully resolve the wall shear stress and correctly normalize the boundary
layer streamwise velocity to wall units where PIV and PIV + PTV showed larger
deviations. Analysis of the turbulent velocity fluctuations revealed spurious
results for PIV in close proximity to the wall, leading to significantly
exaggerated and non-physical turbulence intensity. PIV + PTV showed a minor
improvement in this aspect. wOFV did not exhibit this same effect, revealing
that it is more accurate in capturing small-scale turbulent motion in the
vicinity of boundaries. The enhanced vector resolution of wOFV enabled improved
estimation of instantaneous derivative quantities and intricate flow structure
both closer to the wall. These aspects show that, within a reasonable lambda
range, wOFV can improve resolving the turbulent motion occurring in the
vicinity of physical boundaries