Juan P. D'Amato

A CPU-GPU framework for optimizing the quality of large meshes

The automatic generation of 3D finite element meshes (FEM) is still a bottleneck for the simulation of large fluid dynamic problems. Although today there are several algorithms that can generate good meshes without user intervention, in cases where the geometry changes during the calculation and thousands of meshes must be constructed, the computational cost of this process can exceed the cost of the FEM. There has been a lot of work in FEM parallelization and the algorithms work well in different parallel architectures, but at present there has not been much success in the parallelization of mesh generation methods. This paper will present a massive parallelization scheme for re-meshing with tetrahedral elements using the local modification algorithm. This method is frequently used to improve the quality of elements once the mesh has been generated, but we will show it can also be applied as a regeneration process, starting with the distorted and invalid mesh of the previous step. The parallelization is carried out using OpenCL and OpenMP in order to test the method in a multiple CPU architecture and also in Graphics Processing Units (GPUs). Finally we present the speedup and quality results obtained in meshes with hundreds of thousands of elements and different parallel APIs.

Real-time aircraft radar simulator for a navy training system

A real‐time aircraft radar simulation applied in naval training is presented. The implemented algorithm works on a 3D synthesized environment, described by large sets of polygons—a typical scene can have a million of triangles—and the lobe is discretized with a cluster of rays. The radar display is recreated solving fast ray–polygon intersections (a variation of Ray‐Shooting), and mapping them on the screen. This work proposes a new polygonal simplification method and a geometric classification algorithm in order to solve the intersections efficiently. This methodology leads to high fidelity images and real‐time radar simulation, which operates at the specified 15 revolutions per minute rate. The results were tested with trained aircraft pilots.

Ray-casting method to assess the quality of segmented surfaces from 3D images

A novel algorithm to evaluate the quality of surface segmentations extracted from 3D images is presented. The procedure calculates the volume enclosed between the segmented object represented by a triangular mesh and a reference one. The indicator is computed by means of a robust and efficient ray-tracing algorithm. This algorithm is fully parallelizable, and it can run even on GPUs architectures. The method is validated against synthetic cases and segmentations of real medical images.

Efficient scatter model for simulation of ultrasound images from computed tomography data

Background and motivation: Real-time ultrasound simulation refers to the process of computationally creating fully synthetic ultrasound images instantly. Due to the high value of specialized low cost training for healthcare professionals, there is a growing interest in the use of this technology and the development of high fidelity systems that simulate the acquisitions of echographic images. The objective is to create an efficient and reproducible simulator that can run either on notebooks or desktops using low cost devices. Materials and methods: We present an interactive ultrasound simulator based on CT data. This simulator is based on ray-casting and provides real-time interaction capabilities. The simulation of scattering that is coherent with the transducer position in real time is also introduced. Such noise is produced using a simplified model of multiplicative noise and convolution with point spread functions (PSF) tailored for this purpose. Results: The computational efficiency of scattering maps generation was revised with an improved performance. This allowed a more efficient simulation of coherent scattering in the synthetic echographic images while providing highly realistic result. We describe some quality and performance metrics to validate these results, where a performance of up to 55fps was achieved. Conclusion: The proposed technique for real-time scattering modeling provides realistic yet computationally efficient scatter distributions. The error between the original image and the simulated scattering image was compared for the proposed method and the state-of-the-art, showing negligible differences in its distribution.

A tennis training application using 3d gesture recognition

This paper presents a sport training system which recognizes user movements from data of the Wiimote device with accelerometer technology. Recognizing a new gesture involves the normalization of the Wiimote data and searching in a gesture templates database. The Dynamic Time Warping (DTW) comparison algorithm is used as a correlation function to compare the new gesture with every template. Based on prior training, the system can successfully recognize different sport shots. Particularly the system is instantiated for tennis training. The user visualizes the trajectory of the ball in a three-dimensional environment and he can interact with virtual objects that follow Newton dynamics.