Smooth constraints for spline variational modeling

International audienceThis article introduces a new class of constraints for spline variational modeling, which allows more flexible user specification, as a constrained point can `slide' along a spline curve. Such constraints can, for example, be used to preserve correct parameterization of the spline curve. The spline surface case is also studied. Efficient numerical schemes are discussed for real-time solving, as well as interactive visualization during the energy minimization process. Examples are shown, and numerical results discussed

Research in constraint-based layout, visualization, CAD, and related topics : a bibliographical survey

The present work compiles numerous papers in the area of computer-aided design, graphics, layout configuration, and user interfaces in general. There is nearly no conference on graphics, multimedia, and user interfaces that does not include a section on constraint-based graphics; on the other hand most conferences on constraint processing favour applications in graphics. This work of bibliographical pointers may serve as a basis for a detailed and comprehensive survey of this important and challenging field in the intersection of constraint processing and graphics. In order to reach this ambitious aim, and also to keep this study up-to-date, the authors appreciate any comment and update information

Beyond Snapping: Persistent, Tweakable Alignment and Distribution with StickyLines

International audienceAligning and distributing graphical objects is a common, but cumbersome task. In a preliminary study (six graphic designers , six non-designers), we identified three key problems with current tools: lack of persistence, unpredictability of results, and inability to 'tweak' the layout. We created StickyLines, a tool that treats guidelines as first-class objects: Users can create precise, predictable and persistent interactive alignment and distribution relationships, and 'tweaked' positions can be maintained for subsequent interactions. We ran a [2x2] within-participant experiment to compare Sticky-Lines with standard commands, with two levels of layout difficulty. StickyLines performed 40% faster and required 49% fewer actions than traditional alignment and distribution commands for complex layouts. In study three, six professional designers quickly adopted StickyLines and identified novel uses, including creating complex compound guidelines and using them for both spatial and semantic grouping

Multiresolution curve editing with linear constraints

The use of multiresolution control toward the editing of freeform curves and surfaces has already been recognized as a valuable modeling too

Research in constraint-based layout, visualization, CAD, and related topics : a bibliographical survey

The present work compiles numerous papers in the area of computer-aided design, graphics, layout configuration, and user interfaces in general. There is nearly no conference on graphics, multimedia, and user interfaces that does not include a section on constraint-based graphics; on the other hand most conferences on constraint processing favour applications in graphics. This work of bibliographical pointers may serve as a basis for a detailed and comprehensive survey of this important and challenging field in the intersection of constraint processing and graphics. In order to reach this ambitious aim, and also to keep this study up-to-date, the authors appreciate any comment and update information

Feature-rich distance-based terrain synthesis

This thesis describes a novel terrain synthesis method based on distances in a weighted graph. The method begins with a regular lattice with arbitrary edge weights; heights are determined by path cost from a set of generator nodes. The shapes of individual terrain features, such as mountains, hills, and craters, are specified by a monotonically decreasing profile describing the cross-sectional shape of a feature, while the locations of features in the terrain are specified by placing the generators. Pathing places ridges whose initial location have a dendritic shape. The method is robust and easy to control, making it possible to create pareidolia effects. It can produce a wide range of realistic synthetic terrains such as mountain ranges, craters, faults, cinder cones, and hills. The algorithm incorporates random graph edge weights, permits the inclusion of multiple topography profiles, and allows precise control over placement of terrain features and their heights. These properties all allow the artist to create highly heterogeneous terrains that compare quite favorably to existing methods

Integrating Constraints and Direct Manipulation

In this paper, we present techniques for integrating constraint and direct manipulation approaches to geometric modeling. Direct manipulation positioning techniques are augmented to provide the option of making the relationships they establish persistent. Differential constraint techniques are used to maintain these relationships during subsequent editing. Issues in displaying and editing constraints are also addressed. By integrating constraints with direct manipulation, it is possible to buildsystems that provide the power of explicit representation of geometric relationships and the properties which make direct manipulation so attractive. INTRODUCTION Geometric relationships between parts are an important element in geometric models. From the earliest days of interactive systems[13], the benefits of using constraints to explicitly represent these relationships have been known. Although many have discussed the value of constraints, constraintbased approaches have not been successfu..