vis_scan_path.py 文件源码

def update(self,frame,events):
        img = frame.img
        img_shape = img.shape[:-1][::-1] # width,height

        succeeding_frame = frame.index-self.prev_frame_idx == 1
        same_frame = frame.index == self.prev_frame_idx
        gray_img = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

        #vars for calcOpticalFlowPyrLK
        lk_params = dict( winSize  = (90, 90),
                  maxLevel = 3,
                  criteria = (cv2.TERM_CRITERIA_EPS | cv2.TERM_CRITERIA_COUNT, 20, 0.03))

        updated_past_gaze = []

        #lets update past gaze using optical flow: this is like sticking the gaze points onto the pixels of the img.
        if self.past_gaze_positions and succeeding_frame:
            past_screen_gaze = np.array([denormalize(ng['norm_pos'] ,img_shape,flip_y=True) for ng in self.past_gaze_positions],dtype=np.float32)
            new_pts, status, err = cv2.calcOpticalFlowPyrLK(self.prev_gray,gray_img,past_screen_gaze,None,minEigThreshold=0.005,**lk_params)
            for gaze,new_gaze_pt,s,e in zip(self.past_gaze_positions,new_pts,status,err):
                if s:
                    # print "norm,updated",gaze['norm_gaze'], normalize(new_gaze_pt,img_shape[:-1],flip_y=True)
                    gaze['norm_pos'] = normalize(new_gaze_pt,img_shape,flip_y=True)
                    updated_past_gaze.append(gaze)
                    # logger.debug("updated gaze")

                else:
                    # logger.debug("dropping gaze")
                    # Since we will replace self.past_gaze_positions later,
                    # not appedning tu updated_past_gaze is like deliting this data point.
                    pass
        else:
            # we must be seeking, do not try to do optical flow, or pausing: see below.
            pass

        if same_frame:
            # paused
            # re-use last result
            events['gaze_positions'][:] = self.past_gaze_positions[:]
        else:
            # trim gaze that is too old
            if events['gaze_positions']:
                now = events['gaze_positions'][0]['timestamp']
                cutoff = now-self.timeframe
                updated_past_gaze = [g for g in updated_past_gaze if g['timestamp']>cutoff]

            #inject the scan path gaze points into recent_gaze_positions
            events['gaze_positions'][:] = updated_past_gaze + events['gaze_positions']
            events['gaze_positions'].sort(key=lambda x: x['timestamp']) #this may be redundant...

        #update info for next frame.
        self.prev_gray = gray_img
        self.prev_frame_idx = frame.index
        self.past_gaze_positions = events['gaze_positions']