[visionlist] geometrically ambiguous images

[Lewis Griffin]

The Kapoor sculpture shown at the link is not the one I had in mind. 

In the one I recall, the hole interior was painted apparently uniformly, but
in actual fact in such a way to counteract the shading because of
light-source vignetting, and the lightening because of self-illumination,
that normal happens in a recess.

The triple of possible percepts - patch, window, hole - were obtainable over
at least a 20 degree range of viewing angles.

	Lewis Griffin

Computer Science
University College London
UK

> >http://image.guardian.co.uk/sys-
> images/Guardian/Pix/gallery/2001/05/30/kapoor.jpg
> >
> >>  There is a sculpture by Anish Kapoor, exhibited at the Hayward Gallery
> >>  in London last decade, which provokes a tri-stable perception.
> >>
> >>  >From memory, the sculpture is of a large (1m+) smooth greyish
> >>  >boulder, with
> >>  a roughly hemispherical hole (30cm diameter) excavated into it. The
> >>  interior of the hole has been meticulously painted with light-grey
> >>  pigments of varying lightness. Three percepts are possible:
> >>
> >>   As a light-grey painted patch on the boulder's surface
> >>   As a translucent window into the boulder's interior, which is lit.
> >  >  As a hole.
> >  >
> 
> 
> Hmm. Looking at the photo on the web, I see a fourth percept: a dark
> gray disk floating in front of the boulder.
> 
> Todd
> 
> --
> Todd S. Horowitz, PhD
> Instructor in Ophthalmology
> Harvard Medical School
> Visual Attention Lab
> 64 Sidney Street, Suite 170
> Cambridge, MA 02139
> phone:	(617) 768-8813
> fax:	(617) 768-8816, (617)
> http://search.bwh.harvard.edu/