1. A computer implemented method of detecting one or more vehicles in a video frame acquired from a fixed parking occupancy video camera including a field of view associated with a vehicle parking region, the method comprising: a) capturing a video frame from the fixed parking occupancy video, the video frame including a ROI (Region of Interest) oriented by an orientation angle relative to an orientation of an image plane associated with the captured video frame, the ROI including one or more parking spaces of the vehicle parking region; b) performing a sliding window-based search for one or more vehicles within the ROI, the sliding window-based search extracting one or more features associated with each of a plurality of candidate search windows representing a set of windows from which one or more mutually exclusive object bounding boxes are selected, each selected mutually exclusive object bounding box associated with a vehicle not associated with the other mutually exclusive object bounding boxes; c) accessing a classifier to classify each candidate search window as including a vehicle or not including a vehicle; and d) suppressing one or more overlapping classified candidate search windows including a common vehicle to eliminate overlapping candidate search windows from detecting the common vehicle, wherein the classified candidate search windows are limited to candidate search windows of one or more predefined window shapes to exclude search windows limited to a partial detection of a vehicle, and candidate search windows which are not suppressed are considered to be the one or more mutually exclusive object bounding boxes representative of the one or more vehicles detected in the video frame.