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Interactive Multiresolution Modeling and 3D Painting with a Haptic Interface inTouch Arthur D. Gregory, Stephen A. Ehmann, Ming C. Lin {gregory, ehmann, lin}@cs.unc.edu Brought to you by : <debug@cs.unc.edu> Abstract 1) Intuitive 3D interface
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Interactive MultiresolutionModeling and 3D Painting with a Haptic Interface inTouch Arthur D. Gregory, Stephen A. Ehmann, Ming C. Lin {gregory, ehmann, lin}@cs.unc.edu Brought to you by : <debug@cs.unc.edu> Deepak Bandyopadhyay / COMP239 / inTouch
Abstract 1) Intuitive 3D interface 2) Interactive multiresolution edit of polygonal mesh 3) “Directly” painting on surface 4) Haptic feedback Rooster created with inTouch • result create interesting and complex 3D objects ! Deepak Bandyopadhyay / COMP239 / inTouch
Motivation • What’s in it for us soon-to-be VR experts ? • We need models! places objects humans Deepak Bandyopadhyay / COMP239 / inTouch
Motivation • What’s in it for us soon-to-be VR experts ? • We need models! • Virtual painting • the next killer app ? • Maybe not, but I still think its cool! © 1996 Brian Heston Deepak Bandyopadhyay / COMP239 / inTouch
Motivation • What’s in it for us soon-to-be VR experts ? • We need models! • Virtual painting • the next killer app ? • Maybe not, but I still think its cool! • Haptics • state of the art technologies • Phantom • H-collide Deepak Bandyopadhyay / COMP239 / inTouch
3D painting • How it all began… • Pat Hanrahan and Paul Haeberli, ‘Direct WYSIWYG Painting and Texturing on 3D Shapes’ (SIGGRAPH 1990) [HH90] • [HH90] allows painting in object space, but… • Model must be divided into micro-polygons • Change colors and material per vertex • Painting is done in 2D parameter space Deepak Bandyopadhyay / COMP239 / inTouch
3D painting a la inTouch • Use texture maps instead of per-vertex colors • Use a 3D “brush function” instead of 2D • inTouch allows direct painting onto object space… Deepak Bandyopadhyay / COMP239 / inTouch
(x,y,z) (u,v) triangle in object space triangle in texture space 3D painting a la inTouch • For each triangle within the brush radius… • Compute the edge equations in texture space • Use them to define a plane equation in object space • Incrementally find 3D position of each texel while rasterizing • Apply brush function at this position and modify the texel • direct painting into texture map… Deepak Bandyopadhyay / COMP239 / inTouch
Multiresolution Mesh Editing • Multi-level model representation related by Loop subdivision rules • Mesh editing by dragging with force feedback at any of the levels • Two deformation styles - slide and stick Deepak Bandyopadhyay / COMP239 / inTouch
Haptics hardware • Sensable Technologies PHANTOMs • 3 or 6 DOF force feedback device Deepak Bandyopadhyay / COMP239 / inTouch
Interfacing with PHANTOM • GHOST toolkit • H-Collide library • collision detection between a haptic probe and environment • need 1000Hz updates! • Hierarchical scene representation • Uses frame-to-frame coherence Deepak Bandyopadhyay / COMP239 / inTouch
force Haptic Display • Mesh modification • Triangle, movement vector, magnitude from H-Collide • Compute new position of triangle and use subdivision rules to update finer mesh levels • Pass new mesh to H-collide and compute coarser mesh levels by averaging Deepak Bandyopadhyay / COMP239 / inTouch
Haptic Display • Painting • H-collide establishes point of contact of probe with model and computes the force • Probe becomes brush with specified color, radius and fall-off • Push harder increase brush radius, deposit more paint Deepak Bandyopadhyay / COMP239 / inTouch
User Interface • 2D menu at edge of 3D scene • Use PHANTOM stylus as mouse Pear by Gentaro Hirota Deepak Bandyopadhyay / COMP239 / inTouch
Prototype system • IR2 as graphics server • PC as haptics server • VRPN for communication • Display on PIT or monitor (not 3D) Deepak Bandyopadhyay / COMP239 / inTouch
Conclusions • User comments: • Easy to modify globally or in detail at a point • Intuitive way of “sculpting” a 3D model • Good haptic feedback • Intuitive way of painting the model directly Fox, by Sarah Hoff (starting model = white icosahedron) Deepak Bandyopadhyay / COMP239 / inTouch
Results • “Garl” - Observe the deformation • Young Silvia the butterfly, 80k triangles • Sylvia painted with inTouch Models and painting by Arthur Gregory Deepak Bandyopadhyay / COMP239 / inTouch
Moving paintbrush Potentially moving real object Future Work • Two handed, multi-user, … • More interesting brush functions… • More interesting force feedback... • 6 DOF... • Paint in “real” 3D space (my project) Deepak Bandyopadhyay / COMP239 / inTouch