def get_neg_windows(self, num, cls=None, window_params=None, max_overlap=0,
max_num_images=250):
"""
Return array of num windows that can be generated with window_params
that do not overlap with ground truth by more than max_overlap.
* If cls is not given, returns ground truth for all classes.
* If max_num_images is given, samples from at most that many images.
"""
sw = SlidingWindows(self, self)
if not window_params:
window_params = sw.get_default_window_params(cls)
all_windows = []
image_inds = self.get_pos_samples_for_class(cls)
max_num = len(image_inds)
inds = image_inds
if max_num_images:
inds = skutil.random_subset(image_inds, max_num_images)
num_per_image = round(1. * num / max_num)
for ind in inds:
image = self.images[ind]
windows = image.get_windows(window_params)
gts = image.get_ground_truth(cls)
for gt in gts.arr:
overlaps = BoundingBox.get_overlap(windows[:, :4], gt[:4])
windows = windows[overlaps <= max_overlap, :]
if windows.shape[0] == 0:
continue
ind_to_take = skutil.random_subset_up_to_N(
windows.shape[0], num_per_image)
all_windows.append(np.hstack(
(windows[ind_to_take, :], np.tile(ind, (ind_to_take.shape[0], 1)))))
all_windows = np.concatenate(all_windows, 0)
return all_windows[:num, :]
def get_neg_samples_for_class(self, cls, number=None, with_diff=False, with_trun=True):
"""
Return array of indices of self.images that contain no objects of this class.
"""
if number == 0:
return np.array([])
pos_indices = self.get_pos_samples_for_class(cls, with_diff, with_trun)
neg_indices = np.setdiff1d(np.arange(len(self.images)), pos_indices, assume_unique=True)
return sorted(skutil.random_subset(neg_indices, number))
