Direct estimation of shape from texture
IEEE Trans. Pattern Anal. and Machine Intell.,
vol. 15, no. 11, pp. 1202--1208, 1993.
Witkin (1981) proposed a maximum likelihood (ML) estimator
of surface orientation based on the observed directional bias of
projected texture elements. However, a drawback of this procedure is
that the estimate is only defined indirectly in terms of a set of
non-linear equations. In this paper we propose an alternative
method, which allows an estimate of the surface orientation to be
computed directly in a single step from certain simple
statistics of the image data.
We also nada that thCVAP/is direct estimate allows Witkin's ML estimate to
be computed to within 0.05 degrees in only two or three iterative steps.
The performance of the new estimator is demonstrated experimentally
and compared to that of the ML estimator, using both synthetic data
and real gray-level images.