temporal-network/tn.py

# Copyright 2021 Zilliz. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import numpy as np
import networkx as nx
from networkx.algorithms.dag import dag_longest_path
from typing import List
from towhee.operator.base import Operator, OperatorFlag
from towhee.types.arg import arg, to_image_color
from towhee import register

def iou(bbox: np.ndarray, gt: np.ndarray) -> np.ndarray:
    """
    IoU calculation for next-step filtering
    Parameters
    ----------
    bbox: bounding box array (n, 4)
    gt: bounding box array (m, 4)
    Returns
    -------
    IoU results with dimension (n, m)
    """
    if len(bbox) == 0 or len(gt) == 0:
        return np.array(0)
    lt = np.maximum(bbox[:, None, :2], gt[:, :2])  # left_top (x, y)
    rb = np.minimum(bbox[:, None, 2:], gt[:, 2:])  # right_bottom (x, y)
    wh = np.maximum(rb - lt + 1, 0)  # inter_area (w, h)
    inter_areas = wh[:, :, 0] * wh[:, :, 1]  # shape: (n, m)
    box_areas = (bbox[:, 2] - bbox[:, 0] + 1) * (bbox[:, 3] - bbox[:, 1] + 1)
    gt_areas = (gt[:, 2] - gt[:, 0] + 1) * (gt[:, 3] - gt[:, 1] + 1)
    IoU = inter_areas / (box_areas[:, None] + gt_areas - inter_areas)
    return np.array(IoU)

def tn(sims: np.ndarray,
       tn_max_step: int = 10, tn_top_k: int = 5, max_path: int = 10,
       min_sim: float = 0.2, min_length: int = 5, max_iou: float = 0.3) -> List[List[int]]:
    """
    TN method for video temporal alignment.
    Reimplemented paper:
    {Tan H K, Ngo C W, Hong R, et al. Scalable detection of partial near-duplicate videos by visual-temporal consistency
     [C]//Proceedings of the 17th ACM international conference on Multimedia. 2009: 145-154.}
    Parameters
    ----------
    sims: input similarity map computed from a copied video pair.
    tn_max_step: max step range in TN.
    tn_top_k: Top k frame similarity selection in TN.
    max_path: max loop for multiply segments detection.
    min_sim: min average similarity score for each aligned segment.
    min_length: min segment length.
    max_iou: max iou for filtering overlap segments (bbox).
    Returns
    -------
    list of temporal aligned copied segments, [query_min, ref_min, query_max, ref_max] for each segment
    """
    infringe_box_list = []
    infringe_score_list = []
    path = 0
    node_pair2id = {}
    node_pair2id[(-1, -1)] = 0

    node_id2pair = {}
    node_id2pair[0] = (-1, -1)  # source

    node_num = 1

    DG = nx.DiGraph()
    DG.add_node(0)

    # get top-k values and indices, shape (Q_LEN, top_k)
    top = min(tn_top_k, sims.shape[1])

    topk_indices = np.argsort(-sims)[:, :top]
    topk_sims = np.take_along_axis(sims, topk_indices, axis=-1)

    # add nodes
    for qf_idx in range(sims.shape[0]):
        for k in range(top):
            rf_idx = topk_indices[qf_idx][k]

            node_id2pair[node_num] = (qf_idx, rf_idx)
            node_pair2id[(qf_idx, rf_idx)] = node_num

            DG.add_node(node_num)
            node_num += 1

    # create graph by adding edges
    for q_i in range(sims.shape[0]):
        r_i = topk_indices[q_i]

        intermediate_rs = np.empty((0,), dtype=np.int32)
        # implements Constraints C1 by limiting range end
        for q_j in range(q_i + 1, min(sims.shape[0], q_i + tn_max_step)):
            r_j = topk_indices[q_j]  # shape (top_k, )

            r_diff = r_j[:, None] - r_i  # dst - src, shape (top_k, top_k)

            # Constraints C2
            C2 = (r_diff > 0) & (r_diff < tn_max_step)

            # Constraints C3
            if len(intermediate_rs) == 0:
                C3 = np.ones(C2.shape, dtype=bool)
            else:
                # "the equal sign" in C3 in paper is wrong because it's contradictory to C2
                cond1 = intermediate_rs[None, :] > r_i[:, None]
                cond2 = intermediate_rs[None, :] < r_j[:, None]
                C3 = np.sum(cond2[:, None, :] & cond1, axis=-1) == 0

            # Constraints C4
            s_j = topk_sims[q_j]  # shape (top_k, )
            s_j = np.repeat(s_j.reshape(-1, 1), r_diff.shape[1], axis=1)  # shape (top_k, top_k)
            C4 = s_j >= min_sim

            val_rows, val_cols = np.where(C2 & C3 & C4)
            val_sims = s_j[val_rows, val_cols]
            # update intermediate_rs
            valid_r_j = r_j[val_rows]
            intermediate_rs = np.unique(np.concatenate([intermediate_rs, valid_r_j]))

            edges = [(node_pair2id[(q_i, r_i[c])], node_pair2id[(q_j, r_j[r])], dict(weight=s))
                     for c, r, s in zip(val_cols, val_rows, val_sims)]

            DG.add_edges_from(edges)

    #logger.info("Graph N {} E {} for sim {}x{}", DG.number_of_nodes(), DG.number_of_edges(), sims.shape[0],
    #            sims.shape[1])

    # link sink node
    for i in range(0, node_num - 1):
        j = node_num - 1

        pair_i = node_id2pair[i]
        pair_j = node_id2pair[j]

        if (pair_j[0] > pair_i[0] and pair_j[1] > pair_i[1] and
                pair_j[0] - pair_i[0] <= tn_max_step and pair_j[1] - pair_i[1] <= tn_max_step):
            DG.add_edge(i, j, weight=0)

    while True:
        if path > max_path:
            break
        longest_path = dag_longest_path(DG)
        for i in range(1, len(longest_path)):
            DG.add_edge(longest_path[i - 1], longest_path[i], weight=0.0)
        if 0 in longest_path:
            longest_path.remove(0)  # remove source node
        if node_num - 1 in longest_path:
            longest_path.remove(node_num - 1)  # remove sink node
        path_query = [node_id2pair[node_id][0] for node_id in longest_path]
        path_refer = [node_id2pair[node_id][1] for node_id in longest_path]

        if len(path_query) == 0:
            break
        score = 0.0
        for (qf_idx, rf_idx) in zip(path_query, path_refer):
            score += sims[qf_idx][rf_idx]
        if score > 0:
            query_min, query_max = min(path_query), max(path_query)
            refer_min, refer_max = min(path_refer), max(path_refer)
        else:
            query_min, query_max = 0, 0
            refer_min, refer_max = 0, 0
        ave_length = (refer_max - refer_min + query_max - query_min) / 2
        ious = iou(np.expand_dims(np.array([query_min, refer_min, query_max, refer_max]), axis=0),
                   np.array(infringe_box_list))
        
        if ave_length > 0 and score / ave_length > min_sim and min(refer_max - refer_min,
                                                query_max - query_min) > min_length and ious.max() < max_iou:
            infringe_box_list.append([int(query_min), int(refer_min), int(query_max), int(refer_max)])
            infringe_score_list.append(score / ave_length)
        path += 1
    return infringe_box_list, infringe_score_list


@register(output_schema=['vec'])
class TemporalNetwork(Operator):
    """
    TemporalNetwork
    """
    def __init__(self, 
       tn_max_step: int = 10, tn_top_k: int = 5, max_path: int = 10,
        min_sim: float = 0.2, min_length: int = 5, max_iou: float = 0.3):
        super().__init__()
        self._tn_max_step = tn_max_step
        self._tn_top_k = tn_top_k
        self._max_path = max_path
        self._min_sim = min_sim
        self._min_length = min_length
        self._max_iou = max_iou 

    def __call__(self, src_video_vec: 'ndarray', dst_video_vec: 'ndarray') -> float:
        sim_map = np.dot(src_video_vec, dst_video_vec.T)
        ranges, scores = tn(sim_map, self._tn_max_step, self._tn_top_k, self._max_path, self._min_sim, self._min_length, self._max_iou)

        return ranges, scores