1. SKETCH-BASED MODELING ZHINAN XU AND MENGYI ZHU

2. MOTIVATION By providing the conversion between 2D sketch and 3D model, the designer will be able to quickly grasp the 3D properties of their sketch and use it as initial model for the future modeling process

3. UI OVERVIEW

4. SKETCHING After clicking “draw” button, the user first sketch on our painter

5. SEMANTIC CLASSIFICATION By clicking the curve, the user classify the curve as feature curve or silhouette curve

6. CURVE MATCHING Support translation, scaling and rotation

7. CURVE MATCHING There are several definitions of curve distances. Definition 1 Definition 2

8. CURVE MATCHING

9. PRIMITIVES FITTINGS Recall that we have vectorized points of the sketch and marked the feature curves. At this step, we will try to fit virtual primitives to the sketch curves to draw 3D models.

10. PRIMITIVE FITTINGS So far, our project supports fitting primitives of Sphere, Cylinder, Cones. User will drag the primitives to match the sketch and while dragging, a run-time optimization step will help to determine the actual shape and placement of the 3D Model.

11. OPTIMIZATION We use Augmented Lagragian Method to find a local maximum solution for the primitives parameters. We make the use of the Objection Function used by A. Shtof et. al. for each primitives.

12. OPTIMIZATION – OBJECTIVE FUNCTION Sphere: Cylinder: Cone:

13. OPTIMIZATION --ALM Better than penalty method Faster Convert from CP to NCP In order to find the local maximum solution of the NCP, we choose to implement the linear BFGS. Fast Require knowledge of derivatives

14. PROBLEMS Since it is an application with user interactions, performance is the most concern. We gave up a lot of accuracy to boost up the speed However, the objective function for cylinder and cone doesn’t work well. Requires about 70 iterations Some absurd parameters yield to smaller objective value

15. FUTURE WORK A global optimization that consider relationship between objects (co-center, con-linear, normal and etc.) A fix of the cylinder and cone objective function so it can give us satisfied result An automatic vectorization process that allow us to load images and do snapping