Browsing by Author "Fujisawa, Makoto"

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    3D Computer Graphics-Based Grass Pixel Simulation System for Color Scale Mapping Method
    (The Eurographics Association, 2023) Mizuno, Akito; Tanaka, Kojiro; Mikawa, Masahiko; Fujisawa, Makoto; Jean-Marie Normand; Maki Sugimoto; Veronica Sundstedt
    Recently, a wide range of media devices have been developed, with increasing emphasis on activities related to media art using natural elements. Although numerous studies have been conducted to harmonize media devices with natural landscapes, there is research on a display device using grass, termed artificial grass display, and its foundational element, artificial grass pixel. The artificial grass pixel employs the mechanism of pin displays and two types of grass to dynamically control the color of the grass. Moreover, studies are being conducted on the method of color scale mapping for the artificial grass pixel. However, there is a problem in experiments in the real space conditions due to the experimental overhead of acquiring a lot of data for color scale mapping. In order to solve this problem, this study aims to replicate and evaluate the artificial grass pixel in a virtual space using Computer Graphics (CG) technology. In this paper, we propose a novel method to estimate characteristic parameters of CG models based on a genetic algorithm to minimize the color difference from a real model. As a result, by performing calibration using multiple sets of real data, it was confirmed that the simulated grass pixel demonstrated color and color scale evaluation results aligned based on the color difference with the grass pixel in the real space.
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    Visual Simulation of Soil-Structure Destruction with Seepage Flows
    (ACM, 2021) Wang, Xu; Fujisawa, Makoto; Mikawa, Masahiko; Narain, Rahul and Neff, Michael and Zordan, Victor
    This paper introduces a method for simulating soil-structure coupling with water, which involves a series of visual effects, including wet granular materials, seepage flows, capillary action between grains, and dam breaking simulation.We develop a seepage flow based SPH-DEM framework to handle soil and water particles interactions through a momentum exchange term. In this framework, water is seen as a seepage flow through porous media by Darcy's law; the seepage rate and the soil permeability are manipulated according to drag coefficient and soil porosity. A water saturation-based capillary model is used to capture various soil behaviors such as sandy soil and clay soil. Furthermore, the capillary model can dynamically adjust liquid bridge forces induced by surface tension between soil particles. The adhesion model describes the attraction ability between soil surfaces and water particles to achieve various visual effects for soil and water. Lastly, this framework can capture the complicated dam-breaking scenarios caused by overtopping flow or internal seepage erosion that are challenging to simulate.