[Colloquium] Date Change: Ira Kemelmacher-Shlizerman, Weizmann Institute of Science @ TTI-C

[Julia MacGlashan]

When:             Wednesday, March 26, 2008 @ 10:00 am

 

Where:            TTI-C Conference Room

 

Who:               Ira Kemelmacher-Shlizerman, Weizmann Institute of Science

 

Topic:              3D Shape Reconstruction from gray-level and two-tone
images

 

 

Lighting has a significant effect on the appearance of objects. At the same
time lighting provides information that can be used to recover the
3-dimensional shape of objects. It is long known that recovering shape from
shading information is ill-posed, yet people appear to have a good sense of
the underlying three-dimensional world already from a single picture. In
this talk I will show how explicit modeling of lighting, along with the
incorporation of prior knowledge, can facilitate 3D reconstruction. 

 

In the first part of my talk I will introduce a novel algorithm for 3D shape
recovery of faces from single images using a single 3D reference model of a
different person's face. The method uses the input image as a guide to mold
the reference model to reach a desired reconstruction. Assuming Lambertian
reflectance and rough alignment of the input image and reference model, we
seek shape, albedo, and lighting that best fit the image while preserving
the rough structure of the model. We demonstrate our method by providing
accurate reconstructions of novel faces overcoming significant differences
in shape due to gender, race, and facial expressions. 

 

I will then discuss 3D reconstruction from two-tone images (Mooney images).
These images are fascinating testimonial to the ability of biological vision
systems to accurately handle and interpret impoverished data. Their
ambiguous nature, face specificity, and sudden interpretability have
fascinated psychologists and neurobiologists throughout the past half a
century and led to a flurry of studies. Our analysis indicates that
reconstruction from such images is very ambiguous even if we consider only
reconstruction along the "Mooney transition curve," the boundary curve
between black and white pixels. However with prior knowledge it is possible
to successfully recover the 3D shape of faces from single Mooney images.

 

This is joint work with Ronen Basri. Parts of the work were done in
collaboration with Boaz Nadler (Weizmann) and David W. Jacobs (Maryland).

 

Contact:          Ronen Basri, TTI-C         ronen.basri at tti-c.org
834-2515

 

 

 

 

 

 

 

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