Interaction with constraints in 3D modeling

Journal ArticleInteractive geometric modeling is an important part of the industrial product design process. This paper describes how constraints can be used to facilitate the interactive definition of geometric objects and assemblies. We have implemented a geometric modeling system that combines the definition of objects by interactive construction operations and specification of geometric constraints. The modeling operations automatically generate constraints to maintain the properties intended by their invocation, and constraints, in turn, determine the degrees of freedom for further interactive mouse-controlled modeling operations. A symbolic geometry constraint solver is employed for solving systems of constraints

3D computational steering with parametrized geometric objects

Computational Steering is the ultimate goal of interactive simulation: researchers change parameters of their simulation and immediately receive feedback on the effect. We present a general and flexible graphics tool that is part of an environment for Computational Steering developed at CWI. It enables the researcher to interactively develop his own interface with the simulation. This interface is constructed with 3D Parametrized Geometric Objects. The properties of the objects are parametrized to output data and input parameters of the simulation. The objects visualize the output of the simulation while the researcher can steer the simulation by direct manipulation of the objects. Several applications of 3D Computational Steering are presented

Outdoor Augmented Reality: State of the Art and Issues

International audienceThe goal of an outdoor augmented reality system is to allow the human operator to move freely without restraint in its environment, to view and interact in real time with geo-referenced data via mobile wireless devices. This requires proposing new techniques for 3D localization, visualization and 3D interaction, adapted to working conditions in outdoor environment (brightness variation, features of displays used, etc.). This paper surveys recent advances in outdoor augmented reality. It resumes a large retrospective of the work carried out in this field, especially on methodological aspects (localization methods, generation of 3D models, visualization and interaction approaches), technological aspects (sensors, visualization devices and architecture software) and industrial aspects

Interaction with constraints in 3D modeling

Journal ArticleInteractive geometric modeling is an important part of the industrial product design process. This paper describes how constraints can be used to facilitate the interactive definition of geometric objects and assemblies. We have implemented a geometric modeling system that combines the definition of objects by interactive construction operations and specification of geometric constraints. The modeling operations automatically generate constraints to maintain the properties intended by their invocation, and constraints, in turn, determine the degrees of freedom for further interactive mouse-controlled modeling operations. A symbolic geometry constraint solver is employed for solving systems of constraints

A Comparison of Interactive Shadows and Multi-View Layouts for Mouse-based 3D Modelling

3D user interfaces allow users to view and interact with objects in a 3D scene and form a key component in many modelling applications used in engineering, medicine and design. Most mouse-based interfaces follow the same multi-view layout (three orthogonal, one perspective). This interface is difficult to understand, as it requires users to integrate all four views and build a 3D mental model. An alternative, Interactive Shadows, has been previously proposed that could improve on the multi-view's shortcomings but has never been formally tested. This paper presents the first quantitative user evaluation (n = 36) of both the multi-view and interactive shadows interfaces to compare their relative effectiveness and usability. Participants completed three types of tasks designed to be representative of object manipulation in current 3D modelling software. Interactive shadows were significantly better (p < 0,05) for tasks requiring participants to estimate distance. This suggests interactive shadows interface might better help users approximate relative object positioning

Using direct manipulation for real-time structural design exploration

Before a new structure can be built, it must be designed. This design phase is a very important step in the building process. The total cost of the structure and its structural performance are largely dependent on the structural design process. The impact of decisions on the design process is initially high and declines as the design matures. However, few computational tools are available for the conceptual design phase; thus, an opportunity exists to create such tools. In the conventional workflow, the architect uses geometric modeling tools and the engineer uses structural analysis tools in sequential steps. Parametric modeling tools represent an improvement to this workflow, as structural analysis plug-ins are available. This allows the architect or engineer to receive structural feedback at an earlier stage, but still as a sequential step to the geometric modeling. The present work aims to improve this workflow by integrating structural feedback with geometric modeling.The user interfaces of conceptual design tools should be interactive and agile enough to follow the designer’s iterative workflow. Direct manipulation involves human-computer interaction, which enables an interactive user interface. In this user interface style, users can directly manipulate on-screen objects using real-world metaphors, which engages the users with their task and encourages further explorations. This is achieved by reducing the perceptual and cognitive resources required to understand and use the interface. New technologies have opened up the possibility of creating new design tools that make use of very direct manipulation. This possibility is further explored in this thesis through the development of two such applications. The first application makes use of multi-touch tablets. The multi-touch interface has literally closed the gap between humans and computers, enabling very direct manipulation interactions with two-dimensional user interfaces. The developed application is an interactive conceptual design tool with real-time structural feedback that allows the user to quickly input and modify structural models through the use of gestures. The second application extends these concepts and ideas into a three-dimensional user interface using an input device named the Leap Motion Controller

An incremental constraint-based approach to support engineering design.

Constraint-based systems are increasingly being used to support the design of products. Several commercial design systems based on constraints allow the geometry of a product to be specified and modified in a more natural and efficient way. However, it is now widely recognised the needs to have a close coupling of geometric constraints (i.e. parallel, tangent, etc) and engineering constraints (Le. performance, costs, weight, etc) to effectively support the preliminary design stages. This is an active research topic which is the subject of this thesis. As the design evolves, the size of the quation set which captures the constraints can get very large depending on the complexity of the product being designed. These constraints are expected to be solved efficiently to guarantee immediate feedback to the designer. Such requirement is also necessary to support constraint-based design within Virtual Environments, where it is necessary to have interactive speed. However, the majority of constraint-based design systems re-satisfy all constraints from scratch after the insertion of a new design constraint. This process is time consuming and therefore hinders interactive design performance when dealing with large constraint sets. This thesis reports research into the investigation of techniques to support interactive constraint-based design. The main focus of this work is on the development of incremental graph-based algorithms for satisfying a coupled set of engineering and geometric constraints. In this research, the design constraints, represented as simultaneous sets of linear and non-linear equations, are stored in a directed graph called Equation Graph. When a new constraint is imposed, local constraint propagation techniques are used to satisfy the constraint and update the current graph solution, incrementally. Constraint cycles are locally identified and satisfied within the Equation Graph. Therefore, these algorithms efiiciently solve large constraint sets to support interactive design. Techniques to support under-constrained geometry are also considered in this research. The concept of soft constraints is introduced to represent the degrees of freedom of the geometric entities. This is used to allow the incremental satisfaction of newly imposed constraints by exploiting under-constrained space. These soft constraints are also used to support direct manipulation of under-constrained geometric entities, enabling the designers to test the kinematic behaviour of the current assembly. A prototype constraint-based design system has been developed to demonstrate the feasibility of these algorithms to support preliminary desig

Eignung von virtueller Physik und Touch-Gesten in Touchscreen-Benutzerschnittstellen für kritische Aufgaben

The goal of this reasearch was to examine if modern touch screen interaction concepts that are established on consumer electronic devices like smartphones can be used in time-critical and safety-critical use cases like for machine control or healthcare appliances. Several prevalent interaction concepts with and without touch gestures and virtual physics were tested experimentally in common use cases to assess their efficiency, error rate and user satisfaction during task completion. Based on the results, design recommendations for list scrolling and horizontal dialog navigation are given.Das Ziel dieser Forschungsarbeit war es zu untersuchen, ob moderne Touchscreen-Interaktionskonzepte, die auf Consumer-Electronic-Geräten wie Smartphones etabliert sind, für zeit- und sicherheitskritische Anwendungsfälle wie Maschinensteuerung und Medizingeräte geeignet sind. Mehrere gebräuchliche Interaktionskonzepte mit und ohne Touch-Gesten und virtueller Physik wurden in häufigen Anwendungsfällen experimentell auf ihre Effizienz, Fehlerrate und Nutzerzufriedenheit bei der Aufgabenlösung untersucht. Basierend auf den Resultaten werden Empfehlungen für das Scrollen in Listen und dem horizontalen Navigieren in mehrseitigen Software-Dialogen ausgesprochen

A system for modelling deformable procedural shapes.

This thesis presents a new procedural paradigm for modelling. The method combines the benefit of compact object descriptions found in procedural modelling along with the advantage of the ability to interact in real-time as is found with interactive modelling techniques. The three main components to this paradigm are geometry generators (the creation of basic object shapes), selectors (the specification of a selection volume), and modifiers (the object transformation functions). The user interacts in real-time with the object, and has complete control over the object formation process. Interaction is stored within appropriate nodes in a creation-history list which can be replayed or partially replayed at any time during the creation process. The parameters associated with each interaction are stored within the node, and are available for editing at any time during the creation process. The concepts presented here remove the problems that most modelling software have, in that the arbitrary editing of object parameters is destructive, in the sense that changing the parameter of one node may cause the object to behave unpredictably. This takes place in real-time, rather than off-line. In some cases real-time interaction is made possible by trading visual quality vs. speed of rendering. This results in the object being rendered at a lower quality, and therefore decisions on whether the object parameters need adjustment may be predicated upon a poor representation of the object. The work presented herein attempts to bridge the divide between the two approaches by providing the user with a powerful and descriptive procedural modelling language that is entirely generated through real-time interaction with the geometric object via an intuitive user interface. The main contributions of this work are that it allows: Procedural objects are specified interactively. Modelling takes place independently of representation (meaning the user does not base their modelling on the (mesh) representation, but rather on the shape they see). Changes to the object are coherent and non-destructive