1. Interactive Modelling
for AR Applications
John Bastian, Ben Ward, Rhys Hill,
Anton van den Hengel, Anthony Dick
Australian Centre for Visual Technologies
School of Computer Science
University of Adelaide

2. Introduction
 Our method allows users to rapidly build
3D models for
Manipulation within AR workspace
Use as occlusion masks
 Our approach is characterised by
An interactive modelling process
Modelling by segmentation and silhouette
carving

3. Overview
 Video an object with a hand-held webcam
 Track camera movement with PTAM
 User selects object in one frame
 System segments object in subsequent frames
 Observations are combined to construct the
3D model

4. Segmentation
 User marks the object, using a
mouse or the camera
 Build foreground and background
colour models from user marking
 Apply graph cut segmentation
 Optimal segmentation given
colour models and image
edges
 Additional marking refines the
segmentation

5. Segmentation

6. Silhouette Carving
 Use the silhouettes
to generate 3D
models
 Start with a volume
around the object
 Remove voxels with
projection outside
the silhouette

7. Feedback
 Current shape estimate is used to
predict subsequent silhouettes
 Predicted silhouette is used to:
Define cut region
Update colour models
Reduce ambiguity when foreground has
similar colour to background

8. 3D Prior
 Silhouette is predicted from
current shape estimate
 Initial mesh used until volume
is defined
 Volume model is used to
generate a confidence map for
inclusion of each pixel in the
silhouette

9. User Feedback
 User can view
the model as
its shape
evolves

10. Results

11. Results

12. Results

13. Future Work
 Register models from a
database to the images
 Incorporate photoconsistency
 Use more sophisticated
segmentation
 Increased automation

14. Questions?