Riccardo Giannitrapani

Three-dimensional skeleton extraction by point set contraction

In this paper, a skeleton extraction method for unstructured three-dimensional data is presented. The algorithm is based on a point set contraction procedure and is proved to be robust to noise and coarse resolution of original data. Preliminary experiments performed on both synthetic and real data are provided, showing the goodness of the proposed method.

Segmentation of underwater 3D acoustical images for augmented and virtual reality applications

In this paper, an algorithm devoted to the segmentation of acoustic three-dimensional sparse images is presented. The goal is the discrimination and the reconstruction of the objects present in an underwater scene. The final aim is to obtain an augmented representation of such images providing a virtual representation of the recognized objects in order to support a human operator for the navigation and inspection of underwater environments.

Virtual environment modeling by integrated optical and acoustic sensing

In this paper, the problem of underwater scene understanding from multisensory data is addressed. Acoustic and optical devices onboard an underwater vehicle are used to sense the environment in order to produce an output which is readily understandable even by an inexperienced operator. The main idea is to integrate multiple sensory data by geometrically registering data to a model. In this way vehicle pose is derived, and the model objects can be superimposed on actual images, generating an augmented reality representation. Results on a real underwater scene are provided, showing the effectiveness of the proposed approach.

The Use of HepRep in GLAST

HepRep is a generic, hierarchical format for description of graphics representables that can be augmented by physics information and relational properties. It was developed for high energy physics event display applications and is especially suited to client/server or component frameworks. The GLAST experiment, an international effort led by NASA for a gamma-ray telescope to launch in 2006, chose HepRep to provide a flexible, extensible and maintainable framework for their event display without tying their users to any one graphics application. To support HepRep in their GUADI infrastructure, GLAST developed a HepRep filler and builder architecture. The architecture hides the details of XML and CORBA in a set of base and helper classes allowing physics experts to focus on what data they want to represent. GLAST has two GAUDI services: HepRepSvc, which registers HepRep fillers in a global registry and allows the HepRep to be exported to XML, and CorbaSvc, which allows the HepRep to be published through a CORBA interface and which allows the client application to feed commands back to GAUDI (such as start next event, or run some GAUDI algorithm). GLAST s HepRep solution gives users a choice of client applications, WIRED (written in Java) or FRED (written in C++ and Ruby), and leaves them free to move to any future HepRep-compliant event display. HepRep is a generic, hierarchical format for description of graphics representables that can be augmented by physics information and relational properties. It was developed for high energy physics event display applications and is especially suited to client/server or component frameworks. The GLAST experiment, an international effort led by NASA for a gamma-ray telescope to launch in 2006, chose HepRep to provide a flexible, extensible and maintainable framework for their event display without tying their users to any one graphics application. This paper describes why GLAST selected HepRep and how they went about implementing a HepRep-based event display in their GAUDI framework.

Augmented representation of underwater scenes by segmentation and reconstruction of 3D acoustic images

In this paper, a system aimed at the augmented representation of underwater scenes is presented. The system operates on three-dimensional acoustic images and is composed of several modules devoted to noise filtering, segmentation in pipe-shaped structures, recognition and reconstruction. Finally, identified objects are backprojected in the acoustic image in order to facilitate its interpretation. The final aim is to obtain an augmented (or virtual) representation of such images providing a useful tool to support a human operator for navigating in and inspecting underwater environments.

GLAST Large Area Telescope simulation tools

This paper presents the simulation of the GLAST high energy gamma-ray telescope. The simulation package, written in C++, is based on the Geant4 toolkit, and it is integrated into a general framework used to process events. A detailed simulation of the electronic signals inside silicon detectors has been provided and it is used for the particle tracking, which is handled by a dedicated software. A unique repository for the geometrical description of the detector has been realized using the XML language and a C++ library to access this information has been designed and implemented. A new event display based on the HepRep protocol is being implemented. The GLAST satellite parameters derived from the simulation are used in a fast simulator to obtain a snapshot of the gamma-ray sky. This paper outlines the contribution developed by the Italian GLAST software group.