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Interactive Mesh Sculpting Using a Haptic Device Goal A method to continuously sculpt or deform a planar mesh using haptic interaction is implemented. Moreover, this mesh has an image of the final model mapped on. Approach Image mapped on a planar mesh Phantom Omni Basic Haptic Device NURBS surface is used Different tools to improve sculpting Force Feedback Foundation It allows the user to interact with it by applying and receiving forces. Interacts with graphics applications Can make objects feel sticky, soft, rough, viscous Previous Work Haptic Device Avoiding interpenetration between virtual objects Allowing the user to paint in virtual environments Teleoperation of objects Touching textures Mesh Sculpting Free Form Deformation Control points define the vertices of a parallelepiped Using control points can be cumbersome Subdivision solids Each subdivided solid has damping, mass and stiffness Virtual clay Characteristics of the Project Haptic Device Movement in 3 dimensions Mouse is constrained to 2 dimensions Limited range of motion Force rendering NURBS Provide advantages over other surfaces Using OpenGL implementation Automatic texture mapping Knot array affects continuity of the surface Particle System Defined as a set of particles that evolves over time Control points in NURBS are the particles Particles have attributes like position, velocity and force Runge-Kutta4 Method used to solve differencial equations dx v dt (1) dv f dt m ( 2) Implementation HLAPI and OpenGL High level haptic rendering Provides rendering/collision detection and useful data structures hlBeginFrame and hlEndFrame Data Structures Vertex class Has attributes like position and velocity ParticleSystem Contains list of control points NURBS Draws the mesh Features/Tools Sculpting Forces are rendered when we touch the surface. Sculpting includes both pushing and pulling the surface. We are using the stylus button to switch between push and pull modes. Brush Induces force on more than one control point at a time This is the point of contact The green points are also affected 3D Paint Painting in the 3D model is reflected on the 2D texture Show/Hide Particles Showing particles Closer look at the image Hiding particles Rotations It allows us to look the image from different angles 3D Cursor It simulates the shape of a pen Force Feedback This is the default mode, but can be disabled. If disabled, no forces are rendered, but the mesh can still be sculpted. Results of this comparison are shown in the Results section. Basic Algorithm 1. 2. 3. Initialize the application Create the mesh and texture map it with the image Sculpt the mesh using the haptic device: a. b. c. 4. 5. Rotate the mesh Select a brush or single point sculpting Apply forces to the mesh The new position for the control point is calculated and the mesh is drawn again. Repeat step 3 until sculpting is done. Major Issues Sense of depth is difficult to implement NURBS sampling parameters needs to be adjusted Haptic device kicked occasionally while rotating the surface Results Comparing the Haptic Device and the Mouse Mouse No force feedback Points moved one at a time, but can move continuously if implemented User touches the control points Picking control points may be difficult Haptic device Force feedback exists Points are moved continuously User touches the mesh since the haptic device provides this configuration No need to pick control points Mapping Haptic Device to Graphics Simulation NURBS in OpenGL An efficient way to draw NURBS Provide different parameters to control the surface The mesh is 12x12 control points Hardware acceleration in the graphics card should be disabled Interactive Sculpting Initial image Final image Lips Deformation Initial image Sculpting the lower lip Side view of the image Common error in the sculpting process Side view of the final mesh Front view of the mesh Comparing Force Feedback and No Force Feedback Haptic device as a 3D mouse Identifying if we are touching the surface Haptic feedback No haptic feedback Lips 4 minutes 2.5 minutes Nose 1.6 minutes 2 minutes Water bottle 6 minutes 6 minutes Finger 3 minutes 3 minutes Door handle 3.5 minutes 3 minutes Mouse 2 minutes 2 minutes Mountain 3 minutes 2 minutes Cream bottle 4 minutes 4 minutes Example This curve in the lips can be clearly created in the first image but does not exist in the second image. The height of the lips does not seem natural in the second image. This line between the lips clearly separates them but it is not the case for the second image. Results Aesthetic quality of the image and 3D model are better when using haptic interaction Some curves in the mesh are not steady Same results can be achieved without force feedback but time will increase. Conclusion Conclusion Haptic interaction provides an easier to use and faster way to sculpt a mesh. We implemented a few of the many tools that will enhance the sculpting process. Practice is needed to perceive the cursor’s Z location. Conclusion Real time interaction is important NURBS provided flexibility and important properties Sense of touch can provide new forms of interaction Future Work Future Work New editing tools E.g. a selection tool Adding NURBS NURBS How knots on the fly parameters should be adjusted limitations to model hands, bottles? Future Work Different views of the mesh Each view has a different angle Integration with image editing software Attract users attention Image recognition Identify boundaries and apply rules to the control points near the boundary 3D Paint