Juncong Lin

Automatic polycube-maps

We propose an automatic PolyCube-Maps construction scheme. Firstly, input mesh is decomposed into a set of feature regions, and further split into patches. Then, each region is approximated by a simple basic polycube primitive with each patch mapped to a rectangular sub-surface of the basic polycube primitive which can be parameterized independently. After that, an iterative procedure is performed to improve the parameterization quality globally. By these steps, we can obtain the polycubic parameterization result efficiently.

Spatial sketch: bridging between movement & fabrication

Spatial Sketch is a three-dimensional (3D) sketch application that bridges between physical movement and the fabrication of objects in the real world via cut planar materials. This paper explores the rationale and details behind the development of the Spatial Sketch application, and presents our observations from user testing and a hands-on lamp shade design workshop. Finally we reflect upon the relevance of embodied forms of human computer interaction for use in digital fabrication.

A Sketching Interface for Sitting Pose Design in the Virtual Environment

Character pose design is one of the most fundamental processes in computer graphics authoring. Although there are many research efforts in this field, most existing design tools consider only character body structure, rather than its interaction with the environment. This paper presents an intuitive sketching interface that allows the user to interactively place a 3D human character in a sitting position on a chair. Within our framework, the user sketches the target pose as a 2D stick figure and attaches the selected joints to the environment (e.g., the feet on the ground) with a pin tool. As reconstructing the 3D pose from a 2D stick figure is an ill-posed problem due to many possible solutions, the key idea in our paper is to reduce solution space by considering the interaction between the character and environment and adding physics constraints, such as balance and collision. Further, we formulated this reconstruction into a nonlinear optimization problem and solved it via the genetic algorithm (GA) and the quasi-Newton solver. With the GPU implementation, our system is able to generate the physically correct and visually pleasing pose at an interactive speed. The promising experimental results and user study demonstrates the efficacy of our method.

Mesh Composition on Models with Arbitrary Boundary Topology

This paper presents a new approach for the mesh composition on models with arbitrary boundary topology. After cutting the needed parts from existing mesh models and putting them into the right pose, an implicit surface is adopted to smoothly interpolate the boundaries of the models under composition. An interface is developed to control the shape of the implicit transient surface by using sketches to specify the expected silhouettes. After that, a localized Marching Cubes algorithm is investigated to tessellate the implicit transient surface so that the mesh surface of the composed model is generated. Different from existing approaches in which the models under composition are required to have pairwise merging boundaries, the framework developed based on our techniques have the new function to fuse models with arbitrary boundary topology.

Creature grammar for creative modeling of 3D monsters

Monsters and strange creatures are frequently demanded in 3D games and movies. Modeling such kind of objects calls for creativity and imagination. Especially in a scenario where a large number of monsters with various shapes and styles are required, the designing and modeling process becomes even more challenging. We present a system to assist artists in the creative design of a large collection of various 3D monsters. Starting with a small set of shapes manually selected from different categories, our system iteratively generates sets of monster models serving as the artists reference and inspiration. The key component of our system is a so-called creature grammar, which is a shape grammar tailored for the generation of 3D monsters. Creature grammar governs the evolution from creatures with regular structures gradually into monsters with more and more abnormal structures through evolving the arrangement and number of shape parts, while preserving the semantics prescribed as prior knowledge. Experiments show that even starting with a small set of shapes from a few categories of common creatures (e.g., humanoids, bird-like creatures and quadrupeds), our system can produce a large set of unexpected monsters with both shape diversity and visual plausibility, thus providing great support for the users creative design.

A sketching interface for sitting-pose design

We present a sketch interface for interactively placing a 3D human character in a sitting position on a chair. The user first sketches the target pose as a 2D stick figure. The user can specify whether a joint will be attached to the environment (for example, the feet may be put on the ground) with a pin tool. Our system then reconstructs the 3D pose from the sketch figure considering the constraints specified by the user and the interaction between the character and the environment. This paper presents a user interface and a reconstruction algorithm that combines a genetic algorithm and a quasi-Newton solver to efficiently find a collision-free pose. An informal user study showed the effectiveness of our approach.

Mesh fusion using functional blending on topologically incompatible sections

Three-dimensional mesh fusion provides an easy and fast way to create new mesh models from existing ones. We introduce a novel approach of mesh fusion in this paper based on functional blending. Our method has no restriction of disk-like topology or one-ring opening on the meshes to be merged. First of all, sections with boundaries of the under-fusing meshes are converted into implicit representations. An implicit transition surface, which joins the sections together while keeping smoothness at the boundaries, is then created based on cubic Hermite functional blending. Finally, the implicit surface is tessellated to form the resultant mesh. Our scheme is both efficient and simple, and with it users can easily construct interesting, complex 3D models.

Harmonic quorum systems: Data management in 2D/3D wireless sensor networks with holes

With the development of ever-expanding wireless sensor networks (WSNs) that are meant to connect physical worlds with human societies, gathering sensory data at a single point is becoming less and less practical. Unfortunately, the alternative in-network data management schemes may fail to operate in the face of communication voids (or holes) in WSNs (especially 3D WSNs). In response to this challenge, we propose harmonic quorum systems (HQSs) as a lightweight data management system for 2D/3D WSNs. HQSs innovate in exploiting a few scalar fields (constructed using pure localized algorithms) to guide data accesses. This liberates HQSs from depending on any routing mechanisms or location services, hence making HQSs efficient and robust against anomalies in WSN topologies. We implement HQSs in TinyOS, and we perform intensive simulations using TOSSIM to validate the performance of HQSs.

A multi-touch interface for fast architectural sketching and massing

Architectural sketching and massing are used by designers to analyze and explore the design space of buildings. This paper describes a novel multi-touch interface for fast architectural sketching and massing of tall buildings. It incorporates a family of multi-touch gestures, enabling one to quickly sketch the 2D contour of a base floor plan and extrude it to model a building with multi-floor structures. Further, it provides a set of gestures to users: select and edit a range of floors; scale contours of a building; copy, paste, and rotate a building, i.e., create a twisted structure; edit profile curves of a buildings profile; and collapse and remove a selected range of floors. The multi-touch system also allows users to apply textures or geometric facades to the building, and to compare different designs side-by-side. To guide the design process, we describe interactions with a domain expert, a practicing architect. The final interface is evaluated by architects and students in an architecture Dept., which demonstrates that the system allows rapid conceptual design and massing of novel multi-story building structures.

SnapBlocks: a snapping interface for assembling toy blocks with XBOX Kinect

Toy blocks can help the children develop various skills, such as spatial, mathematical, creative problem solving etc. In this paper, we developed a computer aided system for child to play blocks with a computer in a natural and intuitive way using the Kinect. We design a set of intuitive body gestures that allow the user to naturally control and navigate 3D toy blocks in a virtual environment. To conquer the imprecise interaction with Kinect, we propose a snapping interface, which automatically computes the optimal location and orientation of the to-be-assembled block. This interface can significantly reduce the user’s burden for fine tuning the blocks at the desired locations, which is often tedious and time consuming. As a result, the user can fully immerse him/herself in the game and construct a complicated structure easily. The experimental results and positive feedback from users demonstrate the efficacy of our approach to virtual assembly of building blocks.