21 Relational Descriptions in Picture Processing H. G. Barrow and R. J. Popplestone

We have written a program which will recognize a range of objects including a cup, a wedge, a hammer, a pencil, and a pair of spectacles. A visual image, represented by a 64.x 64 array of light levels, is first partitioned into connected regions. These regions are chosen to have welldefined edges. Having chosen the regions, the program then computes properties of and relations between regions. Properties include shape as defined by Fourier analysis of the s--tfr equation of the bounding curve. A typical relation between regions is the degree of adjacency. Finally, the program matches the actual relational structure of the regions of the picture with ideal relational structures representing various objects, using a heuristic search procedure, and selects that object whose relational structure best matches the actual picture. INTRODUCTION In November 1969, a Mark i robot device (Barrow and Salter 1970) was connected on-line to the ICI, 4130 computer of the Department of Machine Intelligence and Perception, University of Edinburgh.