Skip to Main content Skip to Navigation

Estimation de l'échelle absolue par vision passive monofocale et application à la mesure 3D de néoplasies en imagerie coloscopique

Abstract : Vision-based metrology devices generally embed stereoscopic sensors or active measurement systems. Most of the passive 3D reconstruction techniques (Structure-from-Motion, Shape from-Shading) adapted to monocular vision suffer from scale ambiguity. Because the processing of image acquisition implies the loss of the depth information, there is an ambiguous relationship between the depth of a scene and the size of an imaged object. This study deals with the estimation of the absolute scale of a scene using passive monofocal vision. Monofocal vision describes monocular system for which optical parameters are fixed. Such optical systems are notably embedded within endoscopic systems used in colonoscopy. This minimally invasive technique allows endoscopists to explore the colon cavity and remove neoplasias (abnormal growths of tissue). Their size is an essential diagnostic criterion for estimating their rate of malignancy. However, it is difficult to estimate and erroneous visual estimations lead to neoplasias surveillance intervals being inappropriately assigned. The need to design a neoplasia measurement system is the core motivation for our study. In the first part of this manuscript, we review state-of-the-art vision-based metrology devices to provide context for our system. We then introduce monofocal optical systems and the specific image formation model used in our study. The second part deals with the main contribution of our work. We first review in detail state of the art DfD (Depth-from-Defocus) and DfF (Depth-from-Defocus) approaches. They are passive computer vision techniques that enable us to resolve scale ambiguity. Our core contribution is introduced in the following chapter. We define the Infocus-Breakpoint (IB) that allows us to resolve scale from a regular video. The IB is the lower limit of the optical system’s depth of field. Our system relies on two novel technical modules: Blur-Estimating Tracking (BET) and Blur-Model Fitting (BMF). BET allows us to simultaneously track an area of interest and estimate the optical blur information. BMF allows us to robustly extract the IB by fitting an optical blur model to the blur measurement estimated by the BET module. For the optical system is monofocal, the IB corresponds to a reference depth that can be calibrated. In the last chapter, we evaluate our method and propose a neoplasia measurement system adapted to the constraints in colonoscopy examination. The last part of this manuscript is dedicated to a prospect of extension of our method by a generative approach. We present, as a preliminary study, a new NRSfM (Non-Rigid Structure-from-Motion) method allowing the scaled Euclidean 3D reconstruction of deformable surfaces. This approach is based on the simultaneous estimation of dense depth maps corresponding to a set of deformations as well as the in-focus color map of the flattened surface. We first review state-of-the-art methods for 3D reconstruction of deformable surfaces. We then introduce our new generative model as well as an alternation method allowing us to infer it.
Document type :
Complete list of metadatas

Cited literature [174 references]  Display  Hide  Download
Contributor : Abes Star :  Contact
Submitted on : Tuesday, June 19, 2018 - 3:25:06 PM
Last modification on : Tuesday, September 8, 2020 - 3:48:41 AM
Long-term archiving on: : Tuesday, September 25, 2018 - 12:53:27 PM


Version validated by the jury (STAR)


  • HAL Id : tel-01818783, version 1


François Chadebecq. Estimation de l'échelle absolue par vision passive monofocale et application à la mesure 3D de néoplasies en imagerie coloscopique. Imagerie médicale. Université Blaise Pascal - Clermont-Ferrand II, 2015. Français. ⟨NNT : 2015CLF22612⟩. ⟨tel-01818783⟩



Record views


Files downloads