Transcript Interactive Hierarchical Space Carving with Projector-based Calibrations Martin Granger-Piché, Emric Epstein, Pierre Poulin { grangem | epsteine | poulin } @ iro.umontreal.ca Results Interactive System.

Interactive Hierarchical Space Carving
with Projector-based Calibrations
Martin Granger-Piché, Emric Epstein, Pierre Poulin
{ grangem | epsteine | poulin } @ iro.umontreal.ca
Results
Interactive System Pipeline
normal feedback loop
continuous
intervention
move camera
or
move object
or
zoom camera on object
silhouette carving
on dynamic image list
image
• acquisition
• cleanup
• calibration
visualization
of current
3D model
…
system initialization
increase subdivision on
entire model or selected region
Abstract
We present an interactive reconstruction system based on space
carving. The user controls the camera and object positions and their
impact on the reconstruction is immediately displayed. The flow of
images is used first for silhouette carving, and then representative
images are stored in a hemispherical structure for balanced color
carving. Projected color points on the measured background or on
the object (acquired by structured light) allow for automatic and
adapted calibration of the camera. The octree-based object representation is central to our space carving algorithm: voxels are
efficiently carved out at their largest size, images are treated at their
appropriate level, and 3D regions are subdivided only when
necessary.
occasional
intervention
threshold modification for
color comparison
generation of structured light
calibration points
save current 3D model
Projector-based Calibrations
color carving
on static and dynamic
image structures
on user
request
…
static
dynamic
Octree-based Space Carving
Contributions
1. Interactive system
• tools to give control to the user
• visual feedback loop
• real-time simultaneous image acquisition, segmentation,
calibration, and reconstruction display
16x16x16
2. Projector-based calibrations
32x32x32
• automatic camera calibration with projected color points
• zoomed camera calibration with projected points on the
object, which are obtained with structured light
• automatic stand tracking
3. Octree-based space carving
• compactness :
subdivision of only external boundary voxels
• efficiency : largest voxels are carved before subdivided
• hardware visible voxels detection
• appropriate octree level for each image
64x64x64
4. Image processing
• RGB ellipsoid : fast and robust color detection
• automatic background segmentation
All structured light points
Selected valid points to allow
zoomed in camera calibration
256x256x256
Our
Technique
Standard
Space
Carving