Research

My current researches are focused on developing the software CityZoom.

CityZoom Analytics - COVID-19

CityZoom Analytics is a CityZoom module that offers analytical visualization applied to spatial-temporal data of city places where people, who tested positive for COVID-19, were during the infectious asymptomatic period. We assume that the territorial model of cities allows the identification of the urban areas most subject to the risk of COVID-19 dissemination. Such identification can assist in supporting decision-making in the management performed by city halls and the government, helping planning the restrictions imposed by the risk of the rapid spread of the disease, identifying and mapping the areas of the city (with an accuracy of land or building) where efforts should be concentrated on action prevention.

News:

Social Medias:

ADufrgs

TV:

- RDC TV - Portal RDC (NET channel 524 -- television program (at 3h13min)

CityZoom

CityZoom is a Decision Support System (DSS) for urban planning which allows users to reconstruct the 3D city model from 2D CAD files and evaluate/modify the city model according to different constraints such as illuminance, visibility, shadow analysis, terrain's previous conditions, etc..

By simulating specific urban regulations and addressing environmental comfort issues, CityZoom helps architects to simultaneously evaluate the different attributes of a particular design.

Coupled with GIS tools, CityZoom allows users to perform multiple analyses over the existing database and use the resultant feedback to optimize proposed solutions.

Simulação de visibilidade e oclusão em quarteirões históricos: análise comparativa dos softwares ArcGIS, CityEngine e CityZoom

Benamy Turkienicz, Guilherme Kruger Dalcin, Rodrigo Pereira Lersch, Renato Silveira

Gestão & Tecnologia de Projetos

2019

A equilibrada coexistência entre novas construções e conjuntos históricos costuma ajudar a preservar ambiências urbanas e a reforçar o protagonismo de edifícios de inegável valor plástico e cultural. Muitas vezes, restrições construtivas originadas em descrições subjetivas do espaço urbano geram excessos indesejáveis como a redução da atratividade de investimentos e a estagnação das relações sociais e econômicas existentes nestes lugares. Nos dias de hoje, ferramentas computacionais e tecnologias de visualização podem ser utilizadas para aumentar a percepção sobre limiares de interferência visual de novas construções sobre edificações históricas e, se criteriosamente utilizadas, podem contribuir para subsidiar a análise objetiva de impactos urbanísticos conferindo celeridade ao licenciamento das novas construções.

Modelos computacionais podem ser utilizados para descrever, numérica e graficamente, espaços oclusos de áreas históricas e “mapear” a interferência de novas edificações. Tecnologias utilizadas para edição de projetos de arquitetura hoje disponíveis não oferecem este mapeamento: este artigo compara o desempenho de ferramentas computacionais que utilizam conceitos elementares de oclusão e visibilidade na aferição de impactos visuais urbanos. A comparação tem por objetivo diferenciar características funcionais destas ferramentas para representar e mensurar espaços dentro e fora dos campos visuais de transeuntes.

O trabalho se divide em quatro partes. A primeira parte descreve os modelos conceituais de oclusão e visibilidade e suas aplicações computacionais em três softwares escolhidos para a análise comparativa: ArcGIS, CityEngine e Cityzoom. A segunda parte apresenta os métodos utilizados pelos três softwares para simulação e mensuração de “envelopes oclusos” em quarteirões históricos. Os métodos são testados, na terceira parte, em estudo de caso constituído por quadras do Centro Histórico da cidade de Pelotas - RS. Os resultados obtidos mostram diferenças entre modelos de dados: ArcGIS e CityEngine computam as partes visíveis dos volumes existentes, enquanto Cityzoom computa volumes virtuais em oclusão. Se os três softwares analisados contribuem para a aferição do impacto de novas edificações em ambiente urbano contendo edificações históricas, o software Cityzoom permite a modelagem e mensuração automática, conferindo maior rapidez de resposta em relação aos dois outros softwares.

Paper Bibtex Video Slides Source

Configurable Flows

Renato Silveira

PhD Thesis - UFRGS

2015

In this work, we propose a new solution to agent navigation based upon boundary value problems (BVP), called Configurable Flows, to control steering behaviors of characters in dynamic environments. We use a potential field formalism that allows synthetic actors to move negotiating space, avoiding collisions, and attaining goals while producing very individual paths. The individuality of each character can be set by changing its inner field parameters leading to a broad range of possible behaviors without jeopardizing its performance.

BVP Path Planners generate potential fields through a differential equation whose gradient descent represents navigation routes from any point of the environment to a goal position. Resulting paths are smooth and free from local minima. In spite of these advantages, these kinds of planners consume a lot of time to produce a solution.

Our approach combines a BVP Path Planner with the Full Multigrid Method, which solves elliptic partial differential equations using a hierarchical strategy. The proposed planner enables real-time performance in large environments. Results show that our proposal spends less than 1% of the time needed to compute a solution using the original BVP planners in several environments. We refine our Path Planner by introducing a new form of the core equation that permits to easily cope with terrain inhomogeneities. This is accomplished by locally changing the concavity/ convexity of the potential, and then creating regions with higher or lower navigation preferences.

As the potential field requires several steps to converge, this approach can be expensive computationally. To overcome this problem, we integrate this novel core equation to the hierarchical planner, emerging a wide variety of applications. We believe our proposal can contribute to several areas of research including agent navigation, pathfinding for games, crowd simulation and robotics. Our publications reinforce the relevance of the proposed method.

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Hierarchical Configurable Flows: a path-planning method for real-time agents

Renato Silveira, Edson Prestes, Luciana Nedel

To appear

Path planning is the basis for autonomous agent navigation and has been a central research topic in different areas such as navigation in virtual worlds and games. While a robust technique is essential, the main concern has been about the huge challenge of unifying quality and efficiency. Attempting to unify these requirements, in this paper we present a new hierarchical algorithm that allows fast navigation of agents in interactive virtual worlds.

Our algorithm uses the solution of a Boundary Value Problem to generate potential fields through a differential equation whose gradient descent represents navigation routes from any point of the environment to a goal position. By configuring these flows, we generate smooth, natural and free from local minima paths. In spite of these advantages, the performance of the planners based on potential fields is significantly low. Here, we reduce the complexity of these planners using a hierarchical strategy based on the \emph{Full Multigrid} method.

Our hierarchical path-planner uses the same principle to handle different terrain traversal capabilities and to control the steering behavior of characters. Synthetic actors can move negotiating space, avoiding collisions, and attaining goals, while producing individual paths. Our strategy enables real-time performance on large environments. Results show that the time spent to compute a solution is comparable with the A* algorithm.

Paper Bibtex Video Slides Source

Planejamento de Movimento para Grupos utilizando Campos Potenciais

Renato Silveira

MSc Dissertation - UFRGS

2008

The simulation of pedestrians represented as virtual humans in a synthetic world is of great interest in areas as cinema, architecture, and games. This activity can be defined as navigation in virtual environments and involves mainly the specification of the environment, the definition of the agent’s initial position as well as its target position in the world (also called goal). By setting these parameters, a motion planning algorithm, or a path-planning algorithm, in particular, can be used to find a trajectory to be followed by it. However, in the real world, if we consider several persons (all in the same initial position) trying to reach the same target position, each individual path followed will be different. That is, for the same task, the strategy used by each person to reach their goal will depend on their physical constitution (body type), personality, mood, and reasoning.

Taking these questions into consideration, this work presents a study about motion planning for pedestrians. As a practical result, a planner which supplies smooth and varied trajectories was developed. The trajectories are also depending on the individual characteristics of each agent, which can be dynamically changed. The method adopted is based on the use of potential fields generated by numerical solutions of boundary value problems involving the equation of Laplace (harmonic functions) and the problem of Sturm- Liouville. Potential fields generated in this manner produce smooth and local minima free trajectories. The behavior of each agent is determined by the alteration of its individual potential field which is generated to each step of the simulation. Thus, it is possible to dynamically modify the standard of the trajectory and at the same time to prevent collisions with mobile obstacles (other agents in the simulation).

On the other hand, the produced behaviors can be used isolatedly or combined in complex moves. Therefore, it is possible to use a function that defines a trajectory. It is also possible to quantify a detour to the left or to the right when the agent sights an obstacle ahead. The implementation of the method, including speed control techniques and agent’s orientation, and situations like the simulation of behaviors in corridors or open regions, will be presented and argued.

Paper Bibtex Video Slides Source

Transporte eletrônico em sistemas nanoscópicos desordenados

Renato Silveira

Trabalho de Conclusão de Curso (TCC) - UFLA

2006

This work has as objective to analyze regimes of electronic transport of unidimensional conducting nanowires in the presence of two types of disorder, structural and compositional. We describe the nanowire using a simplified model for its electronic structure, where atoms of different materials are represented by different values of potential energy. The nanowire disordered part is represented, then, for a sequence of potential barriers.

The wire conductance is directly related to the transmission coefficient of an electron, which can be obtained from the solution of the system’s Schrödinger equation. The different transport regimes analysis is made through the calculation of the transmission coefficients distribution of ensembles of wires. The results show the transition between different regimes of transport due to a variation of system determined parameters, such as the disorder degree and the wire disordered section length.

Paper Bibtex Video Slides Source

Fast Path-Planning using Multi-Resolution Boundary Value Problem

Renato Silveira, Edson Prestes, Luciana Nedel

IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

2010

BVP Path Planners generate potential fields through a differential equation whose gradient descent represents navigation routes from any point of the environment to a goal position. Resulting paths are smooth and free from local minima. In spite of these advantages, this kind of planners consumes a lot of time to produce a solution.

In this paper, we present a new approach that combines our BVP Path Planner with the Full Multigrid Method, which solves elliptic partial differential equations using a hierarchical strategy. Our new approach, called Hierarchical BVP Path Planner, enables real-time performance on large environments.

Results show that our proposal spends less than 1% of the time needed to compute a solution using our original planner in several environments.

Paper Bibtex Video Slides Source

Path-Planning for RTS Games Based on Potential Fields

Renato Silveira, Leonardo Fischer, José Salini Ferreira, Edson Prestes, Luciana Nedel

Motion in Games

2010

Many games, in particular, RTS games, are populated by synthetic humanoid actors that act as autonomous agents. The navigation of these agents is yet a challenge if the problem involves finding a precise route in a virtual world (path-planning) and moving realistically according to its own personality, intentions, and mood (motion planning).

In this paper, we present several complementary approaches recently developed by our group to produce quality paths and to guide and interact with the navigation of autonomous agents. Our approach is based on a BVP Path Planner that generates potential fields through a differential equation whose gradient descent represents navigation routes.

Resulting paths can deal with moving obstacles, are smooth, and free from local minima. In order to evaluate the algorithms, we implemented our path planner in an RTS game engine.

Paper Bibtex Video Slides Source

GPU Accelerated Path Planning for Multi-agent in Virtual Environments

Leonardo G. Fischer, Renato Silveira, Luciana Nedel

VIII Brazillian Symposium on Games and Digital Entertainment (SBGames)

2009

Many games are populated by synthetic humanoid actors that act as autonomous agents. The animation of humanoids in real-time applications is yet a challenge if the problem involves attaining a precise location in a virtual world (path-planning) and moving realistically according to its own personality, intentions, and mood (motion planning).

In this paper, we present a strategy to implement - using CUDA on GPU - a path planner that produces natural steering behaviors for virtual humans using a numerical solution for boundary value problems. The planner is based on the potential field formalism that allows synthetic actors to move negotiating space, avoiding collisions, and attaining goals, while producing very individual paths. The individuality of each character can be set by changing its inner field parameters leading to a broad range of possible behaviors without jeopardizing its performance.

With our GPU-based strategy, we achieve a speed up to 56 times the previous implementation, allowing its use in situations with a large number of autonomous characters, which is commonly found in games.

Paper Bibtex Video Slides Source

Managing Coherent Groups

Renato Silveira, Edson Prestes, Luciana Nedel

Computer Animation and Virtual Worlds

2008

The animation of groups of characters involves the generation of some interesting steering behaviors like following a single path, moving toward a common objective, and moving while keeping a formation. This paper presents a new approach to manage the movement of groups in dynamic environments using a simple and robust algorithm that includes a strategy to keep formations during the displacement of the group.

Our method is based on a boundary value problem (BVP) involving Laplace’s equation and has two layers. In the ﬁrst one, a group map is built to allow for local control of each individual, while in the second one a path planning is performed for each group as a whole.

Results show that our technique is robust in several situations and can be implemented on GPU, which results in real-time performance for large groups.

Paper Bibtex Video Slides Source

High-Level Path Specification and Group Control for Virtual Characters in Interactive Virtual Environments

Renato Silveira, Edson Prestes, Luciana Nedel

Computer Graphics International Conference (CGI)

2008

Social rules such as following the same path, moving towards a common objective, and moving while keeping a formation are some desirable steering behaviors for the simulation of interactive groups. Moreover, interaction with groups in real-time applications is also a challenge, since hundreds of units should be controlled urgently and efﬁciently.

We propose a robust algorithm to control the movement of groups in interactive environments and a strategy to keep their formations while moving. Our method is based on potential ﬁelds and has two layers. In the ﬁrst one, a formation map is built to allow for local control of each individual, while in the second a path planning is performed for each group as a whole.

The technique proposed combines motion planning for groups with sketch-based navigation control. Results show that our technique is robust in several situations and can be implemented on GPU, which results in real-time performance for large groups.

Paper Bibtex Video Slides Source

Natural Steering Behaviors for Virtual Pedestrians

Renato Silveira, Fábio Dapper, Edson Prestes, Luciana P. Nedel

The Visual Computer

2010

The animation of humanoids in real-time applications is yet a challenge if the problem involves attaining a precise location in a virtual world (path-planning), moving realistically according to its own personality, intentions, and mood (motion planning).

In this paper, we propose a formally complete and low-cost solution based on boundary value problems (BVP) to control the steering behaviors of characters in dynamic environments. We use a potential field formalism that allows synthetic actors to move negotiating space, avoiding collisions, and attaining goals, while producing very individual paths. The individuality of each character can be set by changing its inner field parameters leading to a broad range of possible behaviors without jeopardizing its performance.

To illustrate the technique potentialities, some results exploring situations as steering behavior in corridors with collision avoidance and competition for a goal, and searching for objects in unknown environments are presented and discussed. A proposal to automatically change the size of the field of view of each agent, producing different behaviors is also a contribution of this paper. Some comments about performance are also made to help the reader to evaluate the potential of the method.

Paper Bibtex Video Slides Source

Low-cost Interactive Bicycle System

Renato Silveira, Daniela G. Trevisan, Luciana P. Nedel, Douglas Ramos

Symposium on Virtual and Augmented Reality (SVR)

2007

This paper provides a low-cost implementation of an indoor ergonomic bicycle system allowing the user to navigate in a virtual city. The low-cost approach is guaranteed by using the ARToolkit library as an alternative way to capture the bicycle speed and the use of mouse buttons to control movement direction in the virtual world.

Besides we intend to study the user reaction in relation to different stimuli while the user is exercising. The first scenario is based on a passive video clip stimulus and the second one is based on an interactive virtual stimulus. As a result, usability tests are performed with the goal to identify practical basis that explains how virtual reality interfaces might provide motivation for interactive fitness applications.