K1 of Exact Categories by Mirror Image Sequences

2012 ◽  
Vol 11 (1) ◽  
pp. 155-181 ◽  
Author(s):  
Clayton Sherman
Keyword(s):  
Image Sequence ◽  
Image Sequences ◽  
Mirror Image ◽  
Exact Category ◽  
Exact Sequences ◽  
Exact Categories

AbstractWe establish a presentation for K1 of any small exact category P, based on the notion of “mirror image sequence,” originally introduced by Grayson in 1979; as part of the proof, we show that every element of K1(P) arises from a mirror image sequence. This provides an alternative to Nenashev's presentation in terms of “double short exact sequences.”

Lattices Induced by Modular Pull-back Exact Categories

2012 ◽  
Vol 19 (04) ◽  
pp. 713-726
Author(s):  
Demei Li ◽  
Lin Xin
Keyword(s):  
Modular Lattices ◽  
Exact Category ◽  
Exact Sequences ◽  
Exact Categories

In this paper, we introduce the notion of a modular pull-back exact category, study modular lattices [Formula: see text] and [Formula: see text] on the skeletally small modular pull-back exact category (𝒞,ℰ) and show that there is an isomorphism between these two lattices. We also study short exact sequences of lattices induced by ℰ-exact sequences.

scholarly journals The determination of high-resolution spatio-temporal glacier motion fields from time-lapse sequences

2017 ◽  
Vol 5 (4) ◽  
pp. 861-879 ◽  
Author(s):  
Ellen Schwalbe ◽  
Hans-Gerd Maas
Keyword(s):  
High Resolution ◽  
Vector Fields ◽  
Motion Vector ◽  
Image Sequence ◽  
Image Sequences ◽  
Glacier Surface ◽  
Sequence Processing ◽  
Image Sequence Processing ◽  
Matching Techniques

Abstract. This paper presents a comprehensive method for the determination of glacier surface motion vector fields at high spatial and temporal resolution. These vector fields can be derived from monocular terrestrial camera image sequences and are a valuable data source for glaciological analysis of the motion behaviour of glaciers. The measurement concepts for the acquisition of image sequences are presented, and an automated monoscopic image sequence processing chain is developed. Motion vector fields can be derived with high precision by applying automatic subpixel-accuracy image matching techniques on grey value patterns in the image sequences. Well-established matching techniques have been adapted to the special characteristics of the glacier data in order to achieve high reliability in automatic image sequence processing, including the handling of moving shadows as well as motion effects induced by small instabilities in the camera set-up. Suitable geo-referencing techniques were developed to transform image measurements into a reference coordinate system.The result of monoscopic image sequence analysis is a dense raster of glacier surface point trajectories for each image sequence. Each translation vector component in these trajectories can be determined with an accuracy of a few centimetres for points at a distance of several kilometres from the camera. Extensive practical validation experiments have shown that motion vector and trajectory fields derived from monocular image sequences can be used for the determination of high-resolution velocity fields of glaciers, including the analysis of tidal effects on glacier movement, the investigation of a glacier's motion behaviour during calving events, the determination of the position and migration of the grounding line and the detection of subglacial channels during glacier lake outburst floods.

scholarly journals INTEGRATION OF A GENERALISED BUILDING MODEL INTO THE POSE ESTIMATION OF UAS IMAGES

2016 ◽  
Vol XLI-B1 ◽  
pp. 1057-1064 ◽  
Author(s):  
J. Unger ◽  
F. Rottensteiner ◽  
C. Heipke
Keyword(s):  
Pose Estimation ◽  
Image Sequence ◽  
Image Sequences ◽  
Bundle Adjustment ◽  
Unmanned Aerial System ◽  
Real Image ◽  
Building Model ◽  
Current State ◽  
Image Orientation

A hybrid bundle adjustment is presented that allows for the integration of a generalised building model into the pose estimation of image sequences. These images are captured by an Unmanned Aerial System (UAS) equipped with a camera flying in between the buildings. The relation between the building model and the images is described by distances between the object coordinates of the tie points and building model planes. Relations are found by a simple 3D distance criterion and are modelled as fictitious observations in a Gauss-Markov adjustment. The coordinates of model vertices are part of the adjustment as directly observed unknowns which allows for changes in the model. Results of first experiments using a synthetic and a real image sequence demonstrate improvements of the image orientation in comparison to an adjustment without the building model, but also reveal limitations of the current state of the method.

Automatic Registration of Mobile Mapping System Lidar Points and Panoramic-Image Sequences by Relative Orientation Model

2021 ◽  
Vol 87 (12) ◽  
pp. 913-922
Author(s):  
Ningning Zhu ◽  
Bisheng Yang ◽  
Zhen Dong ◽  
Chi Chen ◽  
Xia Huang ◽  
...  
Keyword(s):  
Image Sequence ◽  
Image Sequences ◽  
Relative Orientation ◽  
Panoramic Image ◽  
Feature Points ◽  
Mobile Mapping ◽  
Orientation Model ◽  
Mapping System ◽  
Panoramic Images ◽  
Mobile Mapping System

To register mobile mapping system (MMS) lidar points and panoramic-image sequences, a relative orientation model of panoramic images (PROM) is proposed. The PROM is suitable for cases in which attitude or orientation parameters are unknown in the panoramic-image sequence. First, feature points are extracted and matched from panoramic-image pairs using the SURF algorithm. Second, these matched feature points are used to solve the relative attitude parameters in the PROM. Then, combining the PROM with the absolute position and attitude parameters of the initial panoramic image, the MMS lidar points and panoramic-image sequence are registered. Finally, the registration accuracy of the PROM method is assessed using corresponding points manually selected from the MMSlidar points and panoramic-image sequence. The results show that three types of MMSdata sources are registered accurately based on the proposed registration method. Our method transforms the registration of panoramic images and lidar points into image feature-point matching, which is suitable for diverse road scenes compared with existing methods.

HIGHER -THEORY OF FORMS I. FROM RINGS TO EXACT CATEGORIES

2019 ◽  
pp. 1-69 ◽  
Author(s):  
Marco Schlichting
Keyword(s):  
Form Parameter ◽  
Hermitian Forms ◽  
Group Completion ◽  
Theory Of Forms ◽  
Exact Sequences ◽  
Exact Categories

We prove the analog for the $K$ -theory of forms of the $Q=+$ theorem in algebraic $K$ -theory. That is, we show that the $K$ -theory of forms defined in terms of an $S_{\bullet }$ -construction is a group completion of the category of quadratic spaces for form categories in which all admissible exact sequences split. This applies for instance to quadratic and hermitian forms defined with respect to a form parameter.

scholarly journals Determination of high resolution spatio-temporal glacier motion fields from time-lapse sequences

2017 ◽  
Author(s):  
Ellen Schwalbe ◽  
Hans-Gerd Maas
Keyword(s):  
High Resolution ◽  
Vector Fields ◽  
High Reliability ◽  
Motion Vector ◽  
Image Sequence ◽  
Image Sequences ◽  
Sequence Processing ◽  
Image Sequence Processing ◽  
Matching Techniques

Abstract. This paper presents a comprehensive method for the determination of motion vector fields of glaciers at high spatial and temporal resolution. These vector fields can be derived from monocular terrestrial camera image sequences and are a valuable data source for glaciological analysis of the motion behaviour of glaciers. The measurement concepts for the acquisition of image sequences are presented, and an automated monoscopic image sequence processing chain is developed. Motion vector fields can be derived with high precision by applying automatic sub-pixel-accuracy image matching techniques on grey value patterns in the image sequences. Well-established matching techniques have been adapted to the special characteristics of the glacier data in order to achieve high reliability in automatic image sequence processing, including the handling of moving shadows as well as motion effects induced by small instabilities in the camera setup. Suitable geo-referencing techniques were developed to transform image measurements into a reference coordinate system. The result of the monoscopic image sequence analysis is a dense raster of glacier surface point trajectories for each image sequence. Each translation vector component in these trajectories can be determined with an accuracy of some centimetres for points at a distance of several kilometres from the camera. Extensive practical validation experiments show that motion vector and trajectory fields derived from monocular image sequences can be used for the determination of high resolution velocity fields of glaciers, for the analysis of the effects of tides on glacier movement, for the investigation of a glacier's motion behaviour during calving events, for the determination of the position and migration of the grounding line and for the detection of sub glacial channels during glacier lake outburst floods.

Object Shift and remnant VP-topicalisation: Danish and Swedish verb particles and ‘let’-causatives

2013 ◽  
Vol 36 (2) ◽  
pp. 219-244 ◽  
Author(s):  
Eva Engels ◽  
Sten Vikner
Keyword(s):  
Image Sequences ◽  
Mirror Image ◽  
Verb Second ◽  
Object Shift ◽  
Order Preservation ◽  
Causative Constructions ◽  
Verb Constructions ◽  
Internal Object ◽  
Particle Verb ◽  
Empirical Database

On the basis of an examination of remnant VP-topicalisation constructions, this paper argues for an order preservation analysis of Scandinavian Object Shift. Extending the empirical database, we account for the phenomena in an Optimality Theoretic framework. The paper focusses on two particular constructions in Danish and Swedish, namely particle verb constructions and causative constructions with Danish lade and Swedish låta ‘let’. It is shown how differences in the VP-internal object position give rise to mirror image sequences concerning Object Shift in connection with verb second (V°-to-I°-to-C° movement) and with remnant VP-topicalisation.

scholarly journals Seeing Global Motion in a Random Dot Image Sequence

i-Perception ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 204166952096110
Author(s):  
Chien-Chung Chen ◽  
Hiroshi Ashida ◽  
Xirui Yang ◽  
Pei-Yin Chen
Keyword(s):  
Random Walk ◽  
Image Sequence ◽  
Image Sequences ◽  
Spatial Context ◽  
Coherent Motion ◽  
Global Motion ◽  
Motion Direction ◽  
Motion Energy ◽  
Random Image ◽  
Perceived Motion

In a stimulus with multiple moving elements, an observer may perceive that the whole stimulus moves in unison if (a) one can associate an element in one frame with one in the next (correspondence) and (b) a sufficient proportion of correspondences signal a similar motion direction (coherence). We tested the necessity of these two conditions by asking the participants to rate the perceived intensity of linear, concentric, and radial motions for three types of stimuli: (a) random walk motion, in which the direction of each dot was randomly determined for each frame, (b) random image sequence, which was a set of uncorrelated random dot images presented in sequence, and (c) global motion, in which 35% of dots moved coherently. The participants perceived global motion not only in the global motion conditions but also in the random image sequences, though not in random walk motion. The type of perceived motion in the random image sequences depends on the spatial context of the stimuli. Thus, although there is neither a fixed correspondence across different frames nor a coherent motion direction, observers can still perceive global motion in the random image sequence. This result cannot be explained by motion energy or local aperture border effects.

Recovery of 3D Non-Rigid Structure from Images Based on Trajectories

2014 ◽  
Vol 651-653 ◽  
pp. 2081-2085
Author(s):  
Ya Ming Wang ◽  
Z. Zhang ◽  
Jun Bao Zheng ◽  
L.L. Tong
Keyword(s):  
Linear Combination ◽  
3D Structure ◽  
Image Sequence ◽  
Human Motion ◽  
Image Sequences ◽  
Experimental Results ◽  
Rigid Object ◽  
Rigid Structure ◽  
Object Based ◽  
Basis Size

In this paper, we address the problem of recovering the 3D structure of a non-rigid object based on trajectories throughout an image sequence. We formulate the 3D non-rigid shape as a linear combination of basis trajectories and compute the rectification matrix using generic algorithm with orthogonal constrains. In order to improve the reconstruction ability, trajectory filters are introduced to eliminate the need for choosing basis size. Experimental results from a human motion image sequences show that the proposed approach is more efficient for recovery of 3D non-rigid structure. Furthermore, the adjustment of basis size is avoided through the success use of trajectory filters.

scholarly journals Comparison of Videostroboscopy to Stroboscopy Derived From High-Speed Videoendoscopy for Evaluating Patients With Vocal Fold Mass Lesions

2016 ◽  
Vol 25 (4) ◽  
pp. 576-589 ◽  
Author(s):  
Maria E. Powell ◽  
Dimitar D. Deliyski ◽  
Robert E. Hillman ◽  
Steven M. Zeitels ◽  
James A. Burns ◽  
...  
Keyword(s):  
Interrater Reliability ◽  
Vocal Fold ◽  
High Speed ◽  
Imaging Techniques ◽  
Image Sequence ◽  
Image Sequences ◽  
Physiological Signal ◽  
Before And After ◽  
Mass Lesions ◽  
Internal Level

Purpose Videostroboscopy (VS) uses an indirect physiological signal to predict the phase of the vocal fold vibratory cycle for sampling. Simulated stroboscopy (SS) extracts the phase of the glottal cycle directly from the changing glottal area in the high-speed videoendoscopy (HSV) image sequence. The purpose of this study is to determine the reliability of SS relative to VS for clinical assessment of vocal fold vibratory function in patients with mass lesions. Methods VS and SS recordings were obtained from 28 patients with vocal fold mass lesions before and after phonomicrosurgery and 17 controls who were vocally healthy. Two clinicians rated clinically relevant vocal fold vibratory features using both imaging techniques, indicated their internal level of confidence in the accuracy of their ratings, and provided reasons for low or no confidence. Results SS had fewer asynchronous image sequences than VS. Vibratory outcomes were able to be computed for more patients using SS. In addition, raters demonstrated better interrater reliability and reported equal or higher levels of confidence using SS than VS. Conclusion Stroboscopic techniques on the basis of extracting the phase directly from the HSV image sequence are more reliable than acoustic-based VS. Findings suggest that SS derived from high-speed videoendoscopy is a promising improvement over current VS systems.

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