Figure 6. Low-Level Actions.
ROLLTO TURNTO PANTO FOCUSTO IRISTO
OVRID ROLL TURN PAN TILT TVMODE SHOOT RANGE FOCUS IRIS
Bottom Level: Machine Language and Hardware
Figure 7. Markov Table for GOTHRUDOOR.
form space. Intersecting lines in the latter correspond
to collinear points in the form. But a problem of infinite slopes arises that makes this transform computationally unwieldy (figure 9).
The second idea comes from an obscure branch of
19th century mathematics called integral geometry.
Mathematicians had theoretical reasons for using an
angle-radius parameterization of a line, rather than
the more familiar slope intercept used by Hough.
Peter Hart noticed that by replacing Hough’s linear
transform with a sinusoidal one, not only is the prob-
lem of infinite slopes avoided, but the new transform
is invariant to choice of coordinate accesses. Hart and
Richard Duda also extended this method to detect
analytic curves in images, and this transform has
been used ever since.