An Interactive Constraint-Based System for Selective Attention in Visual Search

. We face in this paper the problem of model-based object recognition in a scene. Computer vision techniques usually separate the extraction of visual information from the scene from the reasoning on the symbolic data. We propose to interactively intertwine the two parts: the reasoning task on visual information is based on constraint satisfaction techniques. Objects are modeled by means of constraints and constraint propagation recognizes an object in the scene. We extend the classical Constraint Satisfaction Problem (CSP) approach which is not suitable for coping with undefined information. We thus propose an Interactive CSP model for reasoning on partially defined data, generating new constraints which can be used to guide the search and to incrementally process newly acquired knowledge. 1 Introduction Visual search is a very popular paradigm of computer vision, relying the location and identification of a known target in a visual scene. Many studies of human and computer-based vi..

An image analysis approach for automatically re-orienteering CT images for dental implants

In the last decade, computerized tomography (CT) has become the most frequently used imaging modality to obtain a correct pre-operative implant planning. In this work, we present an image analysis and computer vision approach able to identify, from the reconstructed 3D data set, the optimal cutting plane specific to each implant to be planned, in order to obtain the best view of the implant site and to have correct measures. If the patient requires more implants, different cutting planes are automatically identified, and the axial and cross-sectional images can be re-oriented accordingly to each of them. In the paper, we describe the defined algorithms in order to recognize 3D markers (each one aligned with a missed tooth for which an implant has to be planned) in the 3D reconstructed space, and the results in processing red] exams, in terms of effectiveness and precision and reproducibility of the measure

An imaging analysis approach for automatically re-orienteering CT images for dental implants

In the last decade, computerized tomography (CT) has become the most frequently used imaging modality to obtain a correct pre-operative implant planning. In this work, we present an image analysis and computer vision approach able to identify, from the reconstructed 3D data set, the optimal cutting plane specific to each implant to be planned, in order to obtain the best view of the implant site and to have correct measures. If the patient requires more implants, different cutting planes are automatically identified, and the axial and cross-sectional images can be re-oriented accordingly to each of them. In the paper, we describe the defined algorithms in order to recognize 3D markers (each one aligned with a missed tooth for which an implant has to be planned) in the 3D reconstructed space, and the results in processing real exams, in terms of effectiveness and precision and reproducibility of the measure

An Interactive Constraint-Based System for Selective Attention in Visual Search

. We face in this paper the problem of model-based object recognition in a scene. Computer vision techniques usually separate the extraction of visual information from the scene from the reasoning on the symbolic data. We propose to interactively intertwine the two parts: the reasoning task on visual information is based on constraint satisfaction techniques. Objects are modeled by means of constraints and constraint propagation recognizes an object in the scene. We extend the classical Constraint Satisfaction Problem (CSP) approach which is not suitable for coping with undefined information. We thus propose an Interactive CSP model for reasoning on partially defined data, generating new constraints which can be used to guide the search and to incrementally process newly acquired knowledge. Keywords: Machine Vision, Constraint Satisfaction. 1 Introduction Visual search is a very popular paradigm of computer vision, relying the location and identification of a known target in a vis..

Interactive Constraint Satisfaction

. We present an Interactive Constraint Satisfaction model for problems where knowledge is not completely defined at the beginning of the computation, but can be interactively acquired during the computational process. In this case, domains can be partially defined when the constraint satisfaction process starts. Thus, domains are dynamically defined in contrast with classical CSPs where domains are statically defined at the beginning of the constraint satisfaction process. The interactive CSP model copes with incomplete domain definition by propagating constraints on already defined domain values and by adding new constraints on undefined parts of domains. These new constraints can be used to incrementally process new information without restarting a constraint propagation process from scratch each time new information is available. In addition, these constraints can be eventually used in order to guide the knowledge acquisition process. Examples are given in order to show the effectiv..

Enhancing Implant Surgery Planning via Computerized Image Processing

Computerized tomography (CT) and magnetic resolution imaging (MRI) are the medical imaging modalities to deliver cross-sectional images of the human body. In the last decade, CT has become the most frequently used imaging modality for the evaluation of the jaw for dental implants (see [Rot98]). Furthermore, image reformatting software has been developed in order to obtain a correct pre-operative diagnosis and treatment planning regarding osseointegrated implants (see, for instance, [CSIa] and [CSIb]). Previous work (see [Cla90]) has shown that CT images are affected by a distortion ratio from 0 to 6 percent. This might be due to the alignment of the patient during the scanning, to his/her movements and eventually to the saturation of pixels composing the image. To solve the first cause, intraoral stents can be used for centering the patient’s head perpendicularly to the axis of the implant to be installed. However, when more than one implant have to be installed, eventually with very different axes, it is better to not expose the patient to multiple CT scanning, which would be necessary to have different CT acquisitions each one perpendicular to the axis of one of the planned teeth.In this work, we present a software approach for enhancing implant surgical planning in order to get exact morphological measurements of the bone and planned teeth by a single CT acquisition. This is achieved by applying image-processing techniques to the original CT images, in order to produce new CT images lying on different planes, and eventually perpendicular to a different tooth. The resulting software system (named DentalVox) has been implemented in C++ and runs on Intel-based personal computers under the Windows operating system. DentalVox ensures better mechanical results in the design and planning of a dental implant with respect to other similar software tools, being able to reconstruct axial (and panorex and cross-sectional) images once any direction is chosen. This allows to get a better mechanical and aestethic prothesis implantata in the underlying jaw bone morphology

Enhancing implant surgery planning via computerized image processing

Computerized tomography (CT) and magnetic resolution imaging (MRI) are the medical imaging modalities to deliver cross-sectional images of the human body. In the last decade, CT has become the most frequently used imaging modality for the evaluation of the jaw for dental implants. Furthermore, image reformatting software has been developed in order to obtain a correct preoperative diagnosis and treatment planning regarding osseointegrated implants. Previous work has shown that CT images are affected by a distortion ration from 0% to 6%. This might be due to the alignment of the patient during scanning, to his/her movements, or possibly to the saturation of pixels composing the image. In order to solve the former problem, intraoral stents can be used to center the patient's head perpendicular to the axis of the implant to be inserted. However, if more than one implant must be placed - possibly with very different axes - it would be necessary to acquire the corresponding number of tomograms, each perpendicular to the axis of one planned tooth. Obviously, it would be better not to expose the patient to multiple CT scanning. In this work, we present a software approach for enhancing implants surgery planning in order to obtain exact morphological measurements of the bone and planned teeth with a single CT acquisition. This is achieved by applying image-processing techniques to the original CT images, in order to produce new Ct images lying on different planes, and possibly perpendicular to a different tooth. The resulting software system (Dental/Vox) has been implemented in C+ + and runs on Intel-based personal computers under the Windows operating systems. DentalVox ensures better mechanical results in the design and planning of a dental implant compared to other, similar software tools; it can reconstruct axial (and panorex and cross-sectional) images once any direction is chosen. This makes it possible to implant a mechanically and esthetically superior prothesis in the underlying gnathic morphology

From eager to lazy constrained data acquisition: A general framework

Constraint Satisfaction Problems (CSPs) are an effective framework for modeling a variety of real life applications and many techniques have been proposed for solving them efficiently. CSPs are based on the assumption that all constrained data (values in variable domains) are available at the beginning of the computation. However, many non-toy problems derive their parameters from an external environment. Data retrieval can be a hard task, because data can come from a third-party system that has to convert information encoded with signals (derived from sensors) into symbolic information (exploitable by a CSP solver). Also, data can be provided by the user or have to be queried to a database. For this purpose, we introduce an extension of the widely used CSP model, called Interactive Constraint Satisfaction Problem (ICSP) model. The variable domain values can be acquired when needed during the resolution process by means of Interactive Constraints, which retrieve (possibly consistent) information. A general framework for constraint propagation algorithms is proposed which is parametric in the number of acquisitions performed at each step. Experimental results show the effectiveness of the proposed approach. Some applications which can benefit from the proposed solution are also discussed