Evidence for Good Recovery of Lengths of Real Objects Seen with Natural Stereo Viewing

Perception ◽  
1996 ◽  
Vol 25 (2) ◽  
pp. 129-154 ◽  
Author(s):  
John P Frisby ◽  
David Buckley ◽  
Philip A Duke
Keyword(s):  
Structure From Motion ◽  
Oscillatory Motion ◽  
Binocular Viewing ◽  
Good Recovery ◽  
Natural Objects ◽  
Scene Structure ◽  
Real Objects ◽  
Matching Performance

Six experiments are described in which good performance of the task of matching the lengths of two stationary real objects, gnarled wooden sticks, under a variety of binocular viewing conditions, including variations in viewing distances was demonstrated. Relatively poor matching performance was observed when the sticks were viewed monocularly in oscillatory motion, or monocularly and stationary. The results suggest that stereo can support good representations of metric scene structure when length judgments of natural objects are required under (quasi-)natural viewing. The implications of these results for theories of structure from stereo and structure from motion are discussed.

Evidence for Good Recovery of Lengths of Real Objects Seen with Natural Stereo Viewing

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 51-51
Author(s):  
J P Frisby ◽  
D Buckley ◽  
P A Duke
Keyword(s):  
Weber Fraction ◽  
Poor Performance ◽  
Absolute Error ◽  
Binocular Viewing ◽  
Human Vision ◽  
Size Constancy ◽  
Good Recovery ◽  
Scene Structure ◽  
Real Objects ◽  
Matching Performance

How good is human size constancy for real objects seen with natural stereo viewing, which minimises the opportunity for monocular size cues to play a role? This question has attracted renewed interest in recent years, arising mainly from the work of Todd and his colleagues. They have argued, initially from experiments in which stereograms were used, but more recently from studies based on real scenes, that poor performance on length judgment tasks suggests that human vision is weak at computing metric representations. At ECVP '95, we described several experiments demonstrating quite good performance on the task of matching the lengths of two stationary real objects, gnarled wooden sticks, under binocular viewing with head held fixed (1995 Perception24 Supplement, 129). We now report extensions to that work aimed at checking whether this good performance is maintained over three viewing distances (79, 158, and 355 cm), and when test and matching sticks are of different thicknesses. Matching performance was measured with a variety of indices: reliability, accuracy, Weber fraction, and absolute error. Relatively poor performance was observed when the sticks were viewed monocularly at the near and far distances but binocular viewing produced good performance at all distances. These results suggest that stereo can support good representations of metric scene structure when length judgments of natural objects are required under (quasi-)natural viewing. The implications of these results for theories of structure-from-stereo are discussed, and reasons are suggested why our results might differ from those of Todd and his colleagues.

Vision for mobile robots

1992 ◽  
Vol 337 (1281) ◽  
pp. 341-350 ◽  
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
Structure From Motion ◽  
Optic Flow ◽  
Image Sequences ◽  
Additional Constraint ◽  
Feature Points ◽  
Scene Structure ◽  
Corner Points ◽  
Edge Points

Localized feature points, particularly corners, can be computed rapidly and reliably in images, and they are stable over image sequences. Corner points provide more constraint than edge points, and this additional constraint can be propagated effectively from corners along edges. Implemented algorithms are described to compute optic flow and to determine scene structure for a mobile robot using stereo or structure from motion. It is argued that a mobile robot may not need to compute depth explicitly in order to navigate effectively.

scholarly journals HIERARCHICAL STRUCTURE FROM MOTION COMBINING GLOBAL IMAGE ORIENTATION AND STRUCTURELESS BUNDLE ADJUSTMENT

2017 ◽  
Vol XLII-1/W1 ◽  
pp. 535-542
Author(s):  
A. Cefalu ◽  
N. Haala ◽  
D. Fritsch
Keyword(s):  
Structure From Motion ◽  
Bundle Adjustment ◽  
Second Step ◽  
Arbitrary Size ◽  
Scene Structure ◽  
Consistency Constraint ◽  
Camera Parameters ◽  
Image Orientation ◽  
Insufficient Knowledge

Global image orientation techniques aim at estimating camera rotations and positions for a whole set of images simultaneously. One of the main arguments for these procedures is an improved robustness against drifting of camera stations in comparison to more classical sequential approaches. Usually, the process consists of computation of absolute rotations and, in a second step, absolute positions for the cameras. Either the first or both steps rely on the network of transformations arising from relative orientations between cameras. Therefore, the quality of the obtained absolute results is influenced by tensions in the network. These may e.g. be induced by insufficient knowledge of the intrinsic camera parameters. Another reason can be found in local weaknesses of image connectivity. We apply a hierarchical approach with intermediate bundle adjustment to reduce these effects. We adopt efficient global techniques which register image triplets based on fixed absolute camera rotations and scaled relative camera translations but do not involve scene structure elements in the fusion step. Our variant employs submodels of arbitrary size, orientation and scale, by computing relative rotations and scales between - and subsequently absolute rotations and scales for - submodels and is applied hierarchically. Furthermore we substitute classical bundle adjustment by a structureless approach based on epipolar geometry and augmented with a scale consistency constraint.

scholarly journals Non-Incremental Derivation of Scale and Pose from a Network of Relative Orientations

2014 ◽  
Vol XL-3 ◽  
pp. 53-59
Author(s):  
A. Cefalu ◽  
D. Fritsch
Keyword(s):  
Ant Colony Optimization ◽  
Structure From Motion ◽  
Camera Motion ◽  
Simple Method ◽  
Network Characteristics ◽  
Common Reference ◽  
Scene Structure ◽  
Simultaneous Registration ◽  
Levenberg Marquardt ◽  
Sequential Addition

The majority of approaches to Structure from Motion apply an incremental triangulate-and-resect strategy in order to reconstruct camera motion and scene structure in a common reference frame. The sequential addition of images may cause a drifting behaviour during the reconstruction, in some cases causing the process to fail. Over the last decade, more attention has come to non-incremental approaches, which exploit the network characteristics arising from the 2- or 3-view relations, given for a set of images through relative orientations. Most approaches employ rotation registration, followed by translation registration. The latter being carried out with or without simultaneous scene reconstruction. We suggest an approach which starts by estimation of relative scales, followed by simultaneous registration of rotation and translation. The latter is achieved by employing a path-finding algorithm based on Ant- Colony-Optimization. For scale estimation we propose a window-search adaption of Levenberg-Marquardt, which avoids unnecessary matrix inversions. We also suggest a simple method for detection of outlier orientations.

On the Problems of Normative Economics

2007 ◽  
pp. 59-72
Author(s):  
I. Lavrov
Keyword(s):  
Economic Theory ◽  
Political History ◽  
Normative Economics ◽  
Normative Approach ◽  
Normative Analysis ◽  
Positive Elements ◽  
Real Objects ◽  
Methodological Aspects

The author considers theoretical, philosophical and methodological aspects of normative approach in economic theory. The article discusses normative analysis and types of normative and positive elements in economic theory, basing upon difference between abstract and real objects of science. The specific traits of generations as subjects of economic and socio-political history are determined.

Rapid mapping accuracy assessment using low-cost UAV and open-source Structure from Motion

2020 ◽  
Vol 52 ◽  
pp. 55-61
Author(s):  
Ettore Potente ◽  
Cosimo Cagnazzo ◽  
Alessandro Deodati ◽  
Giuseppe Mastronuzzi
Keyword(s):  
Open Source ◽  
Structure From Motion ◽  
Accuracy Assessment ◽  
Low Cost ◽  
Mapping Accuracy ◽  
Rapid Mapping ◽  
Source Structure
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