Search results for "stereovision"
showing 10 items of 11 documents
High Speed Stereovision Setup for Position and Motion Estimation of Fertilizer Particles Leaving a Centrifugal Spreader
2014
EA SPE GEAPSI; International audience; A 3D imaging technique using a high speed binocular stereovision system was developed in combination with corresponding image processing algorithms for accurate determination of the parameters of particles leaving the spinning disks of centrifugal fertilizer spreaders. Validation of the stereo-matching algorithm using a virtual 3D stereovision simulator indicated an error of less than 2 pixels for 90% of the particles. The setup was validated using the cylindrical spread pattern of an experimental spreader. A 2D correlation coefficient of 90% and a Relative Error of 27% was found between the experimental results and the (simulated) spread pattern obtai…
AN APPROACH TO CORRECTING IMAGE DISTORTION BY SELF CALIBRATION STEREOSCOPIC SCENE FROM MULTIPLE VIEWS
2012
International audience; An important step in the analysis and interpretation of video scenes for recognizing scenario is the aberration corrections introduced during the image acquisition in order to provide and correct real image data. This paper presents an approach on distortion correction based on stereoscopic self calibration from images sequences by using a multi-camera system of vision (network cameras). This approach for correcting image distortion brings an elegant and robust technique with good accuracy. Without any knowledge of shooting conditions, the camera's parameters will be estimated. For this, the image key points of interest are extracted from different overlapping views …
A 3-D simulation with virtual stereo rig for centrifugal fertilizer spreading
2012
International audience; Stereovision can be used to characterize of the fertilizer centrifugal spreading process and to control the spreading fertilizer distribution pattern on the ground reference. Fertilizer grains, however, resemble each other and the grain images contain little information on texture. Therefore, the accuracy of stereo matching algorithms in literature cannot be used as a reference for stereo images of fertilizer grains. In order to evaluate stereo matching algorithms applied to images of grains a generator of synthetic stereo particle images is presented in this paper. The particle stereo image generator consists of two main parts: the particle 3D position generator and…
Krustotās un nekrustotās stereoredzes izmaiņas pēc LASIK operācijas
2021
Maģistra darbs uzrakstīts angļu valodā uz 37 lappusēm. Tas satur 10 attēlus, 9 tabulas un darbam ir 49 atsauces uz literatūras avotiem. Pētījuma mērķis bija novērtēt krustotās un nekrustotās disparitātes stereoredzes asumu pirms redzes refraktīvās operācijas, divus, četrus un sešus mēnešus pēc operācijas. Pētījumā piedalījās 102 acu klīnikas pacienti – 65 sievietes un 37 vīrieši vecumā no 19 līdz 45 gadiem. Visiem bija miopija vai miopija ar astigmatismu. Jaunais izveidotais izkliedēto punktu globālais stereoredzes datorizētais tests dod iespēju novērtēt abus disparitātes veidus. Rezultātu analīzē tika secināts, ka nav novērojamas statistiski būtiskas izmaiņas stereoredzes asumā pirms un pē…
Comparison of the strain field of abdominal aortic aneurysm measured by magnetic resonance imaging and stereovision: a feasibility study for predicti…
2015
International audience; The prediction of the risk of rupture of abdominal aortic aneurysm (AAA) is a complex problem. Currently the criteria to predict rupture of abdominal aortic aneurysms are aneurysm diameter and growth rates. It is generally believed that study of the wall strain distribution could be helpful to find a better decision criterion for surgery of aortic aneurysms before their rupture. The wall strain distribution depends on many biological and biomechanical factors such as elastic properties of the aorta, turbulent blood flow, anatomy of the aorta, presence of thrombus or not and so on. Recently, numerical simulations to estimate rupture-potential have received many attent…
Jauna stereoredzes testa izstrāde krustotās un nekrustotās disparitātes novērtēšanai
2017
Darbs uzrakstīts angļu valodā uz 49 lappusēm. Tas satur 47 attēlus, 3 tabulas un atsauces uz 27 literatūras avotiem. Darba mērķis bija izstrādāt jaunu datorizētu stereoredzes testu krustotās un nekrustotās disparitātes novērtēšanai. Lokālās un globālās stereoredzes sliekšņi tika novērtēti pielietojot psihofizikālo trepju metodi. Pētījuma dalībnieku uzdevums bija atpazīt telpiskus attēlus. Stimuliem tika izvēlēti dažādi ekspozīcijas laiki – 5 sekundes (ilgais laiks), 550 ms un 250 ms (īsie laiki). Stereoredzes novērtēšanai papildus tika pielietoti tradicionālie stereotesti – TNO, Titmus tests. Pētījumā piedalījās 37 dalībnieki vecumā no 16 līdz 42 gadiem. Rezultāti tika salīdzināti ņemot vēr…
Korelācija starp fuzionālām rezervēm un maksimālo stereoredzes leņķi
2021
Maģistra darbs ir uzrakstīts angļu valodā uz 43 lappusēm. Tas satur 20 attēlus, 3 tabulas un 63 atsauces uz literatūras avotiem. Pētījuma mērķis bija novērtēt, kāda korelācija pastāv starp fuzionālo verģenču rezervēm un maksimālo stereoredzes leņķi. Pētījumā piedalījās 22 dalībnieki, kuriem tika veikta redzes pārbaude Nove Mesto nad Vahom, Slovākijas klīnikā. Pētījumā tika paveikts, pirmkārt, tika analizētas pozitīvās un negatīvās fuzionālās verģences rezerves un salīdzinātās ar normām. Otrkārt, tika analizēti maksimālie stereoredzes krustotās un nekrustotās disparitātes leņķi. Treškārt, tika analizēta korelācija starp visām iespējamām kombinācijām (starp fuzionālām verģences rezervēm un st…
A New Method to Measure 3D Textile Defects by Using Dual-lens Camera
2013
International audience; Industrial textile fabric with functionalization always has a high standard requirement. Take polytetrafluoroethylene (PTFE) conveyor belt as an example, the base fabrics must be of first-rate quality, with no weaving faults or broken fibers on coated surface [1]. In a previous work, we have proposed an original method to measure the height of the fiber based on variable homography. This measurement is based on a single camera acquiring two successive frames. This scheme is working well, but measurement depends on conveyor speed used for scrolling fabric. In this paper, we propose an improvement by using a new acquisition device based on two mini-lenses assembled as …
Design and modelling a of bimodal camera system
2021
In computer vision, researchers face a challenging concern due to the limited field of view (FoV) when using standard cameras in capturing scenes. This problem of narrow FoV often encountered within applications that involve tasks which are related to the robot vision. Many authors have attempted, in different approaches, to solve this issue by fusing two cameras. However, they failed to improve the registration and fusing errors, where the obtained results still limited and not accurate enough. To deal with this limitation and decrease these errors, we propose a new method of camera calibration based on Interior-Point Optimisation (IPO) algorithm using transformation matrix estimation. Thi…
Real time UAV altitude, attitude and motion estimation from hybrid stereovision
2012
International audience; Knowledge of altitude, attitude and motion is essential for an Unmanned Aerial Vehicle during crit- ical maneuvers such as landing and take-off. In this paper we present a hybrid stereoscopic rig composed of a fisheye and a perspective camera for vision-based navigation. In contrast to classical stereoscopic systems based on feature matching, we propose methods which avoid matching between hybrid views. A plane-sweeping approach is proposed for estimating altitude and de- tecting the ground plane. Rotation and translation are then estimated by decoupling: the fisheye camera con- tributes to evaluating attitude, while the perspective camera contributes to estimating t…