NPAR15

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/12611

Browse

Browsing NPAR15 by Subject "Line and curve generation"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Hybrid-Space Localized Stylization Method for View-Dependent Lines Extracted from 3D Models
    (The Eurographics Association, 2015) Cardona, Luis; Saito, Suguru; David Mould and Pierre Bénard
    We propose a localized stylization method that combines object-space and image-space techniques to locally styl- ize view-dependent lines extracted from 3D models. In the input phase, the user can customize a style and draw strokes by tracing over view-dependent feature lines such as occluding contours and suggestive contours. For each stroke drawn, the system stores its style properties as well as its surface location on the underlying polygonal mesh as a data structure referred as registered stroke. In the rendering phase, a new attraction field leads active contours generated from the registered strokes to match current frame feature lines and maintain the style and path coordinates of strokes in nearby viewpoints. For each registered stroke, a limited surface region referred as influence area is used to improve the line matching accuracy and discard obvious mismatches. The proposed styl- ization system produces uncluttered line drawings that convey additional information such as material properties or feature sharpness and is evaluated by measuring its usability and performance.
  • Thumbnail Image
    Item
    The Markov Pen: Online Synthesis of Free-Hand Drawing Styles
    (The Eurographics Association, 2015) Lang, Katrin; Alexa, Marc; David Mould and Pierre Bénard
    Learning expressive curve styles from example is crucial for interactive or computer-based narrative illustrations. We propose a method for online synthesis of free-hand drawing styles along arbitrary base paths by means of an autoregressive Markov Model. Choice on further curve progression is made while drawing, by sampling from a series of previously learned feature distributions subject to local curvature. The algorithm requires no useradjustable parameters other than one short example style. It may be used as a custom ''random brush'' designer in any task that requires rapid placement of a large number of detail-rich shapes that are tedious to create manually.
  • Thumbnail Image
    Item
    Semi-Automatic Digital Epigraphy from Images with Normals
    (The Eurographics Association, 2015) Berkiten, Sema; Fan, Xinyi; Rusinkiewicz, Szymon; David Mould and Pierre Bénard
    We present a semi-automated system for converting photometric datasets (RGB images with normals) into geometry-aware non-photorealistic illustrations that obey the common conventions of epigraphy (black-and-white archaeological drawings of inscriptions). We focus on rock inscriptions formed by carving into or pecking out the rock surface: these are characteristically rough with shallow relief, making the problem very challenging for previous line drawing methods. Our system allows the user to easily outline the inscriptions on the rock surface, then segment out the inscriptions and create line drawings and shaded renderings in a variety of styles. We explore both constant-width and tilt-indicating lines, as well as locally shape-revealing shading. Our system produces more understandable illustrations than previous NPR techniques, successfully converting epigraphy from a manual and painstaking process into a user-guided semi-automatic process.