Method update

tutorials/fairmot/byte_tracker.py:210–350

(self, im_blob, img0)

        return results

    def update(self, im_blob, img0):
        self.frame_id += 1
        activated_starcks = []
        refind_stracks = []
        lost_stracks = []
        removed_stracks = []

        width = img0.shape[1]
        height = img0.shape[0]
        inp_height = im_blob.shape[2]
        inp_width = im_blob.shape[3]
        c = np.array([width / 2., height / 2.], dtype=np.float32)
        s = max(float(inp_width) / float(inp_height) * height, width) * 1.0
        meta = {'c': c, 's': s,
                'out_height': inp_height // self.opt.down_ratio,
                'out_width': inp_width // self.opt.down_ratio}

        ''' Step 1: Network forward, get detections & embeddings'''
        with torch.no_grad():
            output = self.model(im_blob)[-1]
            hm = output['hm'].sigmoid_()
            wh = output['wh']

            reg = output['reg'] if self.opt.reg_offset else None
            dets, inds = mot_decode(hm, wh, reg=reg, ltrb=self.opt.ltrb, K=self.opt.K)

        dets = self.post_process(dets, meta)
        dets = self.merge_outputs([dets])[1]

        remain_inds = dets[:, 4] > self.opt.conf_thres
        inds_low = dets[:, 4] > 0.2
        inds_high = dets[:, 4] < self.opt.conf_thres
        inds_second = np.logical_and(inds_low, inds_high)
        dets_second = dets[inds_second]
        dets = dets[remain_inds]

        if len(dets) > 0:
            '''Detections'''
            detections = [STrack(STrack.tlbr_to_tlwh(tlbrs[:4]), tlbrs[4]) for
                          tlbrs in dets[:, :5]]
        else:
            detections = []

        ''' Add newly detected tracklets to tracked_stracks'''
        unconfirmed = []
        tracked_stracks = []  # type: list[STrack]
        for track in self.tracked_stracks:
            if not track.is_activated:
                unconfirmed.append(track)
            else:
                tracked_stracks.append(track)

        ''' Step 2: First association, with IOU'''
        strack_pool = joint_stracks(tracked_stracks, self.lost_stracks)
        # Predict the current location with KF
        STrack.multi_predict(strack_pool)
        dists = matching.iou_distance(strack_pool, detections)
        matches, u_track, u_detection = matching.linear_assignment(dists, thresh=self.opt.match_thres)