utils.py

'''
M-LSD
Copyright 2021-present NAVER Corp.
Apache License v2.0
'''
import os
import numpy as np
import cv2
import tensorflow as tf


def pred_lines(image, interpreter, input_details, output_details, input_shape=[512, 512], score_thr=0.10, dist_thr=20.0):
    h, w, _ = image.shape
    h_ratio, w_ratio = [h / input_shape[0], w / input_shape[1]]

    resized_image = np.concatenate([cv2.resize(image, (input_shape[0], input_shape[1]), interpolation=cv2.INTER_AREA), np.ones([input_shape[0], input_shape[1], 1])], axis=-1)
    batch_image = np.expand_dims(resized_image, axis=0).astype('float32')
    interpreter.set_tensor(input_details[0]['index'], batch_image)
    interpreter.invoke()

    pts = interpreter.get_tensor(output_details[0]['index'])[0]
    pts_score = interpreter.get_tensor(output_details[1]['index'])[0]
    vmap = interpreter.get_tensor(output_details[2]['index'])[0]

    start = vmap[:,:,:2]
    end = vmap[:,:,2:]
    dist_map = np.sqrt(np.sum((start - end) ** 2, axis=-1))

    segments_list = []
    for center, score in zip(pts, pts_score):
        y, x = center
        distance = dist_map[y, x]
        if score > score_thr and distance > dist_thr:
            disp_x_start, disp_y_start, disp_x_end, disp_y_end = vmap[y, x, :]
            x_start = x + disp_x_start
            y_start = y + disp_y_start
            x_end = x + disp_x_end
            y_end = y + disp_y_end
            segments_list.append([x_start, y_start, x_end, y_end])
    
    lines = 2 * np.array(segments_list) # 256 > 512
    lines[:,0] = lines[:,0] * w_ratio
    lines[:,1] = lines[:,1] * h_ratio
    lines[:,2] = lines[:,2] * w_ratio
    lines[:,3] = lines[:,3] * h_ratio

    return lines


def pred_squares(image,
                 interpreter,
                 input_details,
                 output_details,
                 input_shape=[512, 512],
                 params={'score': 0.06,
                         'outside_ratio': 0.28,
                         'inside_ratio': 0.45,
                         'w_overlap': 0.0,
                         'w_degree': 1.95,
                         'w_length': 0.0,
                         'w_area': 1.86,
                         'w_center': 0.14}):
    h, w, _ = image.shape
    original_shape = [h, w]

    resized_image = np.concatenate([cv2.resize(image, (input_shape[0], input_shape[1]), interpolation=cv2.INTER_AREA), np.ones([input_shape[0], input_shape[1], 1])], axis=-1)
    batch_image = np.expand_dims(resized_image, axis=0).astype('float32')
    interpreter.set_tensor(input_details[0]['index'], batch_image)
    interpreter.invoke()

    pts = interpreter.get_tensor(output_details[0]['index'])[0]
    pts_score = interpreter.get_tensor(output_details[1]['index'])[0]
    vmap = interpreter.get_tensor(output_details[2]['index'])[0]
    
    start = vmap[:,:,:2] # (x, y)
    end = vmap[:,:,2:] # (x, y)
    dist_map = np.sqrt(np.sum((start - end) ** 2, axis=-1))

    junc_list = []
    segments_list = []
    for junc, score in zip(pts, pts_score):
        y, x = junc
        distance = dist_map[y, x]
        if score > params['score'] and distance > 20.0:
            junc_list.append([x, y])
            disp_x_start, disp_y_start, disp_x_end, disp_y_end = vmap[y, x, :]
            d_arrow = 1.0
            x_start = x + d_arrow * disp_x_start
            y_start = y + d_arrow * disp_y_start
            x_end = x + d_arrow * disp_x_end
            y_end = y + d_arrow * disp_y_end
            segments_list.append([x_start, y_start, x_end, y_end])
            
    segments = np.array(segments_list)
    
    ####### post processing for squares
    # 1. get unique lines
    point = np.array([[0, 0]])
    point = point[0]
    start = segments[:,:2]
    end = segments[:,2:]
    diff = start - end
    a = diff[:, 1]
    b = -diff[:, 0]
    c = a * start[:,0] + b * start[:,1]

    d = np.abs(a * point[0] + b * point[1] - c) / np.sqrt(a ** 2 + b ** 2 + 1e-10)
    theta = np.arctan2(diff[:,0], diff[:,1]) * 180 / np.pi
    theta[theta < 0.0] += 180
    hough = np.concatenate([d[:,None], theta[:,None]], axis=-1)

    d_quant = 1
    theta_quant = 2
    hough[:,0] //= d_quant
    hough[:,1] //= theta_quant
    _, indices, counts = np.unique(hough, axis=0, return_index=True, return_counts=True)
    
    acc_map = np.zeros([512 // d_quant + 1, 360 // theta_quant + 1], dtype='float32')
    idx_map = np.zeros([512 // d_quant + 1, 360 // theta_quant + 1], dtype='int32') - 1
    yx_indices = hough[indices,:].astype('int32')
    acc_map[yx_indices[:,0], yx_indices[:,1]] = counts
    idx_map[yx_indices[:,0], yx_indices[:,1]] = indices
    
    acc_map_np = acc_map
    acc_map = acc_map[None,:,:,None]
    
    ### fast suppression using tensorflow op
    acc_map = tf.constant(acc_map, dtype=tf.float32)
    max_acc_map = tf.keras.layers.MaxPool2D(pool_size=(5,5), strides=1, padding='same')(acc_map)
    acc_map = acc_map * tf.cast(tf.math.equal(acc_map, max_acc_map), tf.float32)
    flatten_acc_map = tf.reshape(acc_map, [1, -1])
    topk_values, topk_indices = tf.math.top_k(flatten_acc_map, k=len(pts))
    _, h, w, _ = acc_map.shape
    y = tf.expand_dims(topk_indices // w, axis=-1)
    x = tf.expand_dims(topk_indices % w, axis=-1)
    yx = tf.concat([y, x], axis=-1)
    ###

    yx = yx[0].numpy()
    indices = idx_map[yx[:,0], yx[:,1]]
    topk_values = topk_values.numpy()[0]
    basis = 5 // 2

    merged_segments = []
    for yx_pt, max_indice, value in zip(yx, indices, topk_values):
        y, x = yx_pt
        if max_indice == -1 or value == 0:
            continue
        segment_list = []
        for y_offset in range(-basis, basis+1):
            for x_offset in range(-basis, basis+1):
                indice = idx_map[y+y_offset,x+x_offset]
                cnt = int(acc_map_np[y+y_offset,x+x_offset])
                if indice != -1:
                    segment_list.append(segments[indice])
                if cnt > 1:
                    check_cnt = 1
                    current_hough = hough[indice]
                    for new_indice, new_hough in enumerate(hough):
                        if (current_hough == new_hough).all() and indice != new_indice:
                            segment_list.append(segments[new_indice])
                            check_cnt += 1
                        if check_cnt == cnt:
                            break
        group_segments = np.array(segment_list).reshape([-1, 2])
        sorted_group_segments = np.sort(group_segments, axis=0)
        x_min, y_min = sorted_group_segments[0,:]
        x_max, y_max = sorted_group_segments[-1,:]

        deg = theta[max_indice]
        if deg >= 90:
            merged_segments.append([x_min, y_max, x_max, y_min])
        else:
            merged_segments.append([x_min, y_min, x_max, y_max])

    # 2. get intersections
    new_segments = np.array(merged_segments) # (x1, y1, x2, y2)
    start = new_segments[:,:2] # (x1, y1)
    end = new_segments[:,2:] # (x2, y2)
    new_centers = (start + end) / 2.0
    diff = start - end
    dist_segments = np.sqrt(np.sum(diff ** 2, axis=-1))

    # ax + by = c
    a = diff[:,1]
    b = -diff[:,0]
    c = a * start[:,0] + b * start[:,1]
    pre_det = a[:,None] * b[None,:]
    det = pre_det - np.transpose(pre_det)

    pre_inter_y = a[:,None] * c[None,:]
    inter_y = (pre_inter_y - np.transpose(pre_inter_y)) / (det + 1e-10)
    pre_inter_x = c[:,None] * b[None,:]
    inter_x = (pre_inter_x - np.transpose(pre_inter_x)) / (det + 1e-10)
    inter_pts = np.concatenate([inter_x[:,:,None], inter_y[:,:,None]], axis=-1).astype('int32')
    
    # 3. get corner information
    # 3.1 get distance
    '''
    dist_segments:
        | dist(0), dist(1), dist(2), ...|
    dist_inter_to_segment1:
        | dist(inter,0), dist(inter,0), dist(inter,0), ... |
        | dist(inter,1), dist(inter,1), dist(inter,1), ... |
        ...
    dist_inter_to_semgnet2:
        | dist(inter,0), dist(inter,1), dist(inter,2), ... |
        | dist(inter,0), dist(inter,1), dist(inter,2), ... |
        ...
    '''

    dist_inter_to_segment1_start = np.sqrt(np.sum(((inter_pts - start[:,None,:]) ** 2), axis=-1, keepdims=True)) # [n_batch, n_batch, 1]
    dist_inter_to_segment1_end = np.sqrt(np.sum(((inter_pts - end[:,None,:]) ** 2), axis=-1, keepdims=True)) # [n_batch, n_batch, 1]
    dist_inter_to_segment2_start = np.sqrt(np.sum(((inter_pts - start[None,:,:]) ** 2), axis=-1, keepdims=True)) # [n_batch, n_batch, 1]
    dist_inter_to_segment2_end = np.sqrt(np.sum(((inter_pts - end[None,:,:]) ** 2), axis=-1, keepdims=True)) # [n_batch, n_batch, 1]
    
    # sort ascending
    dist_inter_to_segment1 = np.sort(np.concatenate([dist_inter_to_segment1_start, dist_inter_to_segment1_end], axis=-1), axis=-1) # [n_batch, n_batch, 2]
    dist_inter_to_segment2 = np.sort(np.concatenate([dist_inter_to_segment2_start, dist_inter_to_segment2_end], axis=-1), axis=-1) # [n_batch, n_batch, 2]

    # 3.2 get degree
    inter_to_start = new_centers[:,None,:] - inter_pts
    deg_inter_to_start = np.arctan2(inter_to_start[:,:,1], inter_to_start[:,:,0]) * 180 / np.pi
    deg_inter_to_start[deg_inter_to_start < 0.0] += 360
    inter_to_end = new_centers[None,:,:] - inter_pts
    deg_inter_to_end = np.arctan2(inter_to_end[:,:,1], inter_to_end[:,:,0]) * 180 / np.pi
    deg_inter_to_end[deg_inter_to_end < 0.0] += 360
    
    '''
    0 -- 1
    |    |
    3 -- 2
    '''
    # rename variables
    deg1_map, deg2_map = deg_inter_to_start, deg_inter_to_end
    # sort deg ascending
    deg_sort = np.sort(np.concatenate([deg1_map[:,:,None], deg2_map[:,:,None]], axis=-1), axis=-1)
    
    deg_diff_map = np.abs(deg1_map - deg2_map)
    # we only consider the smallest degree of intersect
    deg_diff_map[deg_diff_map > 180] = 360 - deg_diff_map[deg_diff_map > 180]
    
    # define available degree range
    deg_range = [60, 120]
    
    corner_dict = {corner_info: [] for corner_info in range(4)}
    inter_points = []
    for i in range(inter_pts.shape[0]):
        for j in range(i + 1, inter_pts.shape[1]):
            # i, j > line index, always i < j
            x, y = inter_pts[i, j, :]
            deg1, deg2 = deg_sort[i, j, :]
            deg_diff = deg_diff_map[i, j]
            
            check_degree = deg_diff > deg_range[0] and deg_diff < deg_range[1]

            outside_ratio = params['outside_ratio'] # over ratio >>> drop it!
            inside_ratio = params['inside_ratio'] # over ratio >>> drop it!
            check_distance = ((dist_inter_to_segment1[i,j,1] >= dist_segments[i] and \
                                 dist_inter_to_segment1[i,j,0] <= dist_segments[i] * outside_ratio) or \
                                (dist_inter_to_segment1[i,j,1] <= dist_segments[i] and \
                                 dist_inter_to_segment1[i,j,0] <= dist_segments[i] * inside_ratio)) and \
                             ((dist_inter_to_segment2[i,j,1] >= dist_segments[j] and \
                                 dist_inter_to_segment2[i,j,0] <= dist_segments[j] * outside_ratio) or \
                                (dist_inter_to_segment2[i,j,1] <= dist_segments[j] and \
                                 dist_inter_to_segment2[i,j,0] <= dist_segments[j] * inside_ratio))

            if check_degree and check_distance:
                corner_info = None

                if (deg1 >= 0 and deg1 <= 45 and deg2 >=45 and deg2 <= 120) or \
                     (deg2 >= 315 and deg1 >= 45 and deg1 <= 120):
                    corner_info, color_info = 0, 'blue'
                elif (deg1 >= 45 and deg1 <= 125 and deg2 >= 125 and deg2 <= 225):
                    corner_info, color_info = 1, 'green'
                elif (deg1 >= 125 and deg1 <= 225 and deg2 >= 225 and deg2 <= 315):
                    corner_info, color_info = 2, 'black'
                elif (deg1 >= 0 and deg1 <= 45 and deg2 >= 225 and deg2 <= 315) or \
                     (deg2 >= 315 and deg1 >= 225 and deg1 <= 315):
                    corner_info, color_info = 3, 'cyan'
                else:
                    corner_info, color_info = 4, 'red' # we don't use it
                    continue
                
                corner_dict[corner_info].append([x, y, i, j])
                inter_points.append([x, y])
    
    square_list = []
    connect_list = []
    segments_list = []
    for corner0 in corner_dict[0]:
        for corner1 in corner_dict[1]:
            connect01 = False
            for corner0_line in corner0[2:]:
                if corner0_line in corner1[2:]:
                    connect01 = True
                    break
            if connect01:
                for corner2 in corner_dict[2]:
                    connect12 = False
                    for corner1_line in corner1[2:]:
                        if corner1_line in corner2[2:]:
                            connect12 = True
                            break
                    if connect12:
                        for corner3 in corner_dict[3]:
                            connect23 = False
                            for corner2_line in corner2[2:]:
                                if corner2_line in corner3[2:]:
                                    connect23 = True
                                    break
                            if connect23:
                                for corner3_line in corner3[2:]:
                                    if corner3_line in corner0[2:]:
                                        # SQUARE!!!
                                        '''
                                        0 -- 1
                                        |    |
                                        3 -- 2
                                        square_list:
                                            order: 0 > 1 > 2 > 3
                                            | x0, y0, x1, y1, x2, y2, x3, y3 |
                                            | x0, y0, x1, y1, x2, y2, x3, y3 |
                                            ...
                                        connect_list:
                                            order: 01 > 12 > 23 > 30
                                            | line_idx01, line_idx12, line_idx23, line_idx30 |
                                            | line_idx01, line_idx12, line_idx23, line_idx30 |
                                            ...
                                        segments_list:
                                            order: 0 > 1 > 2 > 3
                                            | line_idx0_i, line_idx0_j, line_idx1_i, line_idx1_j, line_idx2_i, line_idx2_j, line_idx3_i, line_idx3_j |
                                            | line_idx0_i, line_idx0_j, line_idx1_i, line_idx1_j, line_idx2_i, line_idx2_j, line_idx3_i, line_idx3_j |
                                            ...
                                        '''
                                        square_list.append(corner0[:2] + corner1[:2] + corner2[:2] + corner3[:2])
                                        connect_list.append([corner0_line, corner1_line, corner2_line, corner3_line])
                                        segments_list.append(corner0[2:] + corner1[2:] + corner2[2:] + corner3[2:])
    
    def check_outside_inside(segments_info, connect_idx):
        # return 'outside or inside', min distance, cover_param, peri_param
        if connect_idx == segments_info[0]:
            check_dist_mat = dist_inter_to_segment1
        else:
            check_dist_mat = dist_inter_to_segment2
        
        i, j = segments_info
        min_dist, max_dist = check_dist_mat[i, j, :]
        connect_dist = dist_segments[connect_idx]
        if max_dist > connect_dist:
            return 'outside', min_dist, 0, 1
        else:
            return 'inside', min_dist, -1, -1


    top_square = None

    try:
        map_size = input_shape[0] / 2
        squares = np.array(square_list).reshape([-1,4,2])
        score_array = []
        connect_array = np.array(connect_list)
        segments_array = np.array(segments_list).reshape([-1,4,2])
        
        # get degree of corners:
        squares_rollup = np.roll(squares, 1, axis=1)
        squares_rolldown = np.roll(squares, -1, axis=1)
        vec1 = squares_rollup - squares
        normalized_vec1 = vec1 / (np.linalg.norm(vec1, axis=-1, keepdims=True) + 1e-10)
        vec2 = squares_rolldown - squares
        normalized_vec2 = vec2 / (np.linalg.norm(vec2, axis=-1, keepdims=True) + 1e-10)
        inner_products = np.sum(normalized_vec1 * normalized_vec2, axis=-1) # [n_squares, 4]
        squares_degree = np.arccos(inner_products) * 180 / np.pi # [n_squares, 4]

        # get square score
        overlap_scores = []
        degree_scores = []
        length_scores = []
        
        for connects, segments, square, degree in zip(connect_array, segments_array, squares, squares_degree):
            '''
            0 -- 1
            |    |
            3 -- 2
            
            # segments: [4, 2]
            # connects: [4]
            '''
            
            ###################################### OVERLAP SCORES
            cover = 0
            perimeter = 0
            # check 0 > 1 > 2 > 3
            square_length = []
             
            for start_idx in range(4):
                end_idx = (start_idx + 1) % 4
                
                connect_idx = connects[start_idx] # segment idx of segment01
                start_segments = segments[start_idx]
                end_segments = segments[end_idx]
                
                start_point = square[start_idx]
                end_point = square[end_idx]
                
                # check whether outside or inside
                start_position, start_min, start_cover_param, start_peri_param = check_outside_inside(start_segments, connect_idx)
                end_position, end_min, end_cover_param, end_peri_param = check_outside_inside(end_segments, connect_idx)
                
                cover += dist_segments[connect_idx] + start_cover_param * start_min + end_cover_param * end_min
                perimeter += dist_segments[connect_idx] + start_peri_param * start_min + end_peri_param * end_min
                
                square_length.append(dist_segments[connect_idx] + start_peri_param * start_min + end_peri_param * end_min)
            
            overlap_scores.append(cover / perimeter)    
            ######################################
            ###################################### DEGREE SCORES
            '''
            deg0 vs deg2
            deg1 vs deg3
            '''
            deg0, deg1, deg2, deg3 = degree
            deg_ratio1 = deg0 / deg2
            if deg_ratio1 > 1.0:
                deg_ratio1 = 1 / deg_ratio1
            deg_ratio2 = deg1 / deg3
            if deg_ratio2 > 1.0:
                deg_ratio2 = 1 / deg_ratio2
            degree_scores.append((deg_ratio1 + deg_ratio2) / 2)
            ######################################
            ###################################### LENGTH SCORES
            '''
            len0 vs len2
            len1 vs len3
            '''
            len0, len1, len2, len3 = square_length
            len_ratio1 = len0 / len2 if len2 > len0 else len2 / len0
            len_ratio2 = len1 / len3 if len3 > len1 else len3 / len1
            length_scores.append((len_ratio1 + len_ratio2) / 2)

            ######################################
        
        overlap_scores = np.array(overlap_scores)
        overlap_scores /= np.max(overlap_scores)
            
        degree_scores = np.array(degree_scores)
        #degree_scores /= np.max(degree_scores)
        
        length_scores = np.array(length_scores)

        ###################################### AREA SCORES
        area_scores = np.reshape(squares, [-1, 4, 2])
        area_x = area_scores[:,:,0]
        area_y = area_scores[:,:,1]
        correction = area_x[:,-1] * area_y[:,0] - area_y[:,-1] * area_x[:,0]
        area_scores = np.sum(area_x[:,:-1] * area_y[:,1:], axis=-1) - np.sum(area_y[:,:-1] * area_x[:,1:], axis=-1)
        area_scores = 0.5 * np.abs(area_scores + correction)
        area_scores /= (map_size * map_size) #np.max(area_scores)
        ######################################
        
        ###################################### CENTER SCORES
        centers = np.array([[256 // 2, 256 // 2]], dtype='float32') # [1, 2]
        # squares: [n, 4, 2]
        square_centers = np.mean(squares, axis=1) # [n, 2]
        center2center = np.sqrt(np.sum((centers - square_centers) ** 2))
        center_scores = center2center / (map_size / np.sqrt(2.0))


        '''
        score_w = [overlap, degree, area, center, length]
        '''
        score_w = [0.0, 1.0, 10.0, 0.5, 1.0]
        score_array = params['w_overlap'] * overlap_scores \
                        + params['w_degree'] * degree_scores \
                        + params['w_area'] * area_scores \
                        - params['w_center'] * center_scores \
                        + params['w_length'] * length_scores

        best_square = []

        sorted_idx = np.argsort(score_array)[::-1]
        score_array = score_array[sorted_idx]
        squares = squares[sorted_idx]

    except Exception as e:
        pass
    
    try:
        new_segments[:,0] = new_segments[:,0] * 2 / input_shape[1] * original_shape[1]
        new_segments[:,1] = new_segments[:,1] * 2 / input_shape[0] * original_shape[0]
        new_segments[:,2] = new_segments[:,2] * 2 / input_shape[1] * original_shape[1]
        new_segments[:,3] = new_segments[:,3] * 2 / input_shape[0] * original_shape[0]
    except:
        new_segments = []
    
    try:
        squares[:,:,0] = squares[:,:,0] * 2 / input_shape[1] * original_shape[1]
        squares[:,:,1] = squares[:,:,1] * 2 / input_shape[0] * original_shape[0]
    except:
        squares = []
        score_array = []

    try:
        inter_points = np.array(inter_points)
        inter_points[:,0] = inter_points[:,0] * 2 / input_shape[1] * original_shape[1]
        inter_points[:,1] = inter_points[:,1] * 2 / input_shape[0] * original_shape[0]
    except:
        inter_points = []
        

    return new_segments, squares, score_array, inter_points