Research And Application On Simplification Methods For Sketchy Line Drawings

Line drawing,as an expression tool,is widely used by the designers and artists.People express the object silhouettes and important details through pen drawing on the paper or the tablet.Line drawing allows them to quickly present their design concepts or artistic ideologies,thus plays an important role in industrial design and artistic creation processes.However,it is very difficult to clearly express ideas by only a few of lines.Many more strokes are commonly drawn by the designers first,and removed or redrawn to get the final drawing.It is both time and labor consuming,and limits the efficiency of line drawing.According to the spatial and temporal relationships among strokes,an automatic and general mechanism for the simplification of sketchy line drawing is proposed in this paper.It can convert the rough line drawing to a clear and anti-ambiguity vector graph,and includes three research contents:1.A simplification and vectorization framework is proposed to deal the scanned line drawing.Firstly we over-segment the binary rastered input line drawing bitmap,and introduce an iterative structure refining process to remove redundant regions.Then we extract the skeleton meanwhile initialized topological graph,and refine this topological graph through the iterative refining process to get the improved topology.And finally,we vectorize the line drawing based our improved topology,meanwhile optimize the vectorization result using fitting errors and continuity constraints.Our method converts the raster line drawing to vector graph automatically,and a mount of experiments verify the accuracy and efficiency of our method.2.A simplification method for strokes in line drawings is proposed.Firstly we cluster the input strokes dynamically based on the drawing order and the spatial distance between two strokes;and then we analyze the relationship between any two stroke clusters to identify modifying strokes;after these two steps,we finally simplify and merge the input line drawing.Our method introduce the stroke order and modifying relationship,besides the existing spatial analysis work,thus has advantages on preserving the topological structure in the process of line drawing simplification.3.A line drawing simplification system is designed and implemented according to the aforementioned algorithms.This system can convert the input line drawing bitmap to a vector graph robustly and efficiently.It has user-friendly interface,stable platform and powerful capacities.The purpose of this thesis is to use computer technology automatically convert the complex and sketchy line drawing into the simply vector graphics with clear structures.A large number of user studies have demonstrated that our method can reduce most interferential inaccuracy meanwhile remain most meaningful structures which artists want to express and help them liberate from the boring redraw process,promote the artist's productivity.Our method has very important meaning for the field of industrial design and art creation.