[frumiousirc]

There will be a certain resolution. An oval that is HT'ed will turn into a smeared oblong point in Hough space. There can also be biases in the result.

Circular arcs can be detected but how well depends on how long they are and depending on the amount and shapes of whatever other features exist in the image.

Hough can be thought of as a convolution of an image with a kernel that is a delta function in the parameter space. Peaks in the parameter space are then interpreted as being representative of features in the real space and with the strength of the representation being that of the height of the peak.