3D object reconstruction using computer vision : reconstruction and characterization applications for external human anatomical structures

Tese de doutoramento. Engenharia Informática. Faculdade de Engenharia. Universidade do Porto. 201

LabelFusion: A Pipeline for Generating Ground Truth Labels for Real RGBD Data of Cluttered Scenes

Deep neural network (DNN) architectures have been shown to outperform traditional pipelines for object segmentation and pose estimation using RGBD data, but the performance of these DNN pipelines is directly tied to how representative the training data is of the true data. Hence a key requirement for employing these methods in practice is to have a large set of labeled data for your specific robotic manipulation task, a requirement that is not generally satisfied by existing datasets. In this paper we develop a pipeline to rapidly generate high quality RGBD data with pixelwise labels and object poses. We use an RGBD camera to collect video of a scene from multiple viewpoints and leverage existing reconstruction techniques to produce a 3D dense reconstruction. We label the 3D reconstruction using a human assisted ICP-fitting of object meshes. By reprojecting the results of labeling the 3D scene we can produce labels for each RGBD image of the scene. This pipeline enabled us to collect over 1,000,000 labeled object instances in just a few days. We use this dataset to answer questions related to how much training data is required, and of what quality the data must be, to achieve high performance from a DNN architecture

Improvement of Continuous Wave Radar Measurements in a Partially Controlled Environment

A continuous wave (CW) radar system within a partially controlled environment measures scale model aircraft for mono-static and fully polarimetric radar imaging. Due to a pseudo-far-field setup, wavefront curvature manifests primarily as geometric distortion. Recently proposed phase error models show induced geometric distortion to be independent of aperture size which are verified via measurement for Sensors and Signals Exploitation Laboratory (SSEL) collections. The partially controlled nature of the SSEL introduces stray infrastructural reflections into the measured data. Three methods to reduce stray signals are explored namely: true background subtraction (TBS), running average (RA), and spatial filtering (SF). Of the three methods, SF provides 15 dB improvement in dynamic range revealing underlying SSEL structure. Defocus due to quadratic phase error (QPE) is considered, but shown to be negligible for typical aperture sizes of 20 degrees

3-D surface modelling of the human body and 3-D surface anthropometry

This thesis investigates three-dimensional (3-D) surface modelling of the human body and 3-D surface anthropometry. These are two separate, but closely related, areas. 3-D surface modelling is an essential technology for representing and describing the surface shape of an object on a computer. 3-D surface modelling of the human body has wide applications in engineering design, work space simulation, the clothing industry, medicine, biomechanics and animation. These applications require increasingly realistic surface models of the human body. 3-D surface anthropometry is a new interdisciplinary subject. It is defined in this thesis as the art, science, and technology of acquiring, modelling and interrogating 3-D surface data of the human body. [Continues.

(SI10-124) Inverse Reconstruction Methodologies: A Review

The three-dimensional reconstruction problem is a longstanding ill-posed problem, which has made enormous progress in the field of computer vision. This field has attracted increasing interest and demonstrated an impressive performance. Due to a long era of increasing evolution, this paper presents an extensive review of the developments made in this field. For the three dimensional visualization, researchers have focused on the developments of three dimensional information and acquisition methodologies from two dimensional scenes or objects. These acquisition methodologies require a complex calibration procedure which is not practical in general. Hence, the requirement of flexibility was much needed in all these methods. Due to this emerging factors, many techniques were presented. The methodologies are organized on the basis of different aspects of the three dimensional reconstruction like active method, passive method, different geometrical shapes, etc. A brief analysis and comparison of the performance of these methodologies are also presented