Computer-Aided 3D Creative Modeling

3D characters are indispensable parts in 3D computer games and visual effects for TV and film.Many commercial modeling systems have been developed to tackle vari-ous modeling tasks.However,these tools are extremely complex and require months to master,which limits their applications.In the last few decades,significant progress has been achieved in the research field of 3D modeling.Researchers have introduced various easy-to-use yet powerful modeling techniques:sketch-based 3D modeling techniques,assembly-based modeling techniques,etc.In these methods,3D modeling is a craft-like process,that is,the user knows what he/she wants to make before he/she makes it.How-ever,3D modeling is also an open-ended creative art process,in which the direction or goal may change in an unpredictable way.Therefore,it is of theoretical and practical value to investigate how to provide creativity support to help users achieve best outcome in such an open-ended modeling process.A significant stream of computer aided 3D creative modeling techniques focus on suggesting parts,which could be augmented to the current design.These techniques are characterized by requiring the pre-segmented(and/or pre-labeled)3D model database.The parts can be used are restricted to the predefined ones,which limits the design space.Another kind of computer aided 3D creative modeling methods is the shape suggestion method.This kind of techniques is more appropriate to deal with shapes sharing the same structure from the same category.The main limitation of shape suggestion methods is that they are less appropriate to generate shapes with various topological structures.In the 3D character animation pipeline,modeling is only the first stage.Once a model has been created,it will undergo skinning and fabrication-oriented analysis(e.g.,balanc-ing analysis,joint optimization,etc.).Directly adding skinning and fabrication-oriented analysis as a post-process does not allow for real-time interaction,because "designing-animating-fabrication-oriented 3D processing" is an iterative process.Simply combiningthe three steps may lead to frequent switching between different tools,which heavily de-creases the system efficiency.In this work,we investigate the problems mentioned above.The main contributions of this work are as follows:·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 serv-ing as the artist’s 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 evolves the arrangement and number of shape parts,while preserving the semantics prescribed as prior knowledge.·We present Sketch2Cut,a sketch-based on-demand part suggestion method for creating shapes using sketches.After a user draws a simple abstract sketch which depicts his/her intention,our method creates a 3D proxy based on the input sketch as a search key to retrieve a list of candidate parts,each of which is segmented on-the-fly from the 3D models in the input database using partial matching.Our method first converts the 3D partial matching problem into the multi-view 2D partial matching problem.3D part corresponding to the user intent from the 3D shape is then progressively extracted by a coarse-to-fine strategy.In contrast to prior work,our proxy-to-design approach can customize arbitrary parts from input models and does not rely on predefined parts,which significantly broadens the design space.·We present a unified framework by combining design,skinning and fabrication-oriented analysis.With a small set of preprocessed watertight skinned objects,our system iteratively evolves them into a new shape set.Once the user chooses model of interest,our system merges the surfaces and skeletons,and updates the skinning weights to make it ready for animation.The model can also be converted into a fabricatable object after the fabrication-oriented analysis.Our method first merges the surface of the part and the skeleton of the part.The skinning of the merged part is then quickly updated.The joint position and radius is then optimized by the fabrication-oriented skeleton optimization algorithm.Finally we optimize the in-ner mass distribution,making sure the multi-view balancing.Our system provides a whole pipeline from modeling to animation and fabrication to avoid the frequent switching between different tools.