nbv_reconstruction/utils/data_load.py

import os
import OpenEXR
import Imath
import numpy as np
import json
import cv2

class DataLoadUtil:
    
    @staticmethod
    def get_path(root, scene_idx, frame_idx):
        path = os.path.join(root, f"sequence.{scene_idx}", f"step{frame_idx}")
        return path
    
    @staticmethod
    def read_exr_depth(depth_path):
        file = OpenEXR.InputFile(depth_path)

        dw = file.header()['dataWindow']
        width = dw.max.x - dw.min.x + 1
        height = dw.max.y - dw.min.y + 1

        pix_type = Imath.PixelType(Imath.PixelType.FLOAT)
        depth_map = np.frombuffer(file.channel('R', pix_type), dtype=np.float32)

        depth_map.shape = (height, width)
        
        return depth_map

    @staticmethod
    def load_depth(path):
        depth_path = path + ".camera.Depth.exr"
        depth_map = DataLoadUtil.read_exr_depth(depth_path)
        return depth_map
    
    @staticmethod
    def load_rgb(path):
        rgb_path = path + ".camera.png"
        rgb_image = cv2.imread(rgb_path, cv2.IMREAD_COLOR)
        return rgb_image
    
    @staticmethod
    def load_seg(path):
        seg_path = path + ".camera.semantic segmentation.png"
        seg_image = cv2.imread(seg_path, cv2.IMREAD_COLOR)
        return seg_image
    
    @staticmethod
    def load_cam_info(path):
        label_path = path + ".camera_params.json"
        with open(label_path, 'r') as f:
            label_data = json.load(f)
        cam_transform = np.asarray(label_data['cam_to_world']).reshape(
            (4, 4)
        ).T
    
        offset = np.asarray([
            [1, 0, 0, 0],
            [0, -1, 0, 0],
            [0, 0, 1, 0],
            [0, 0, 0, 1]])  

        cam_to_world = cam_transform @ offset
        
        
        
        f_x = label_data['f_x']
        f_y = label_data['f_y']
        c_x = label_data['c_x']
        c_y = label_data['c_y']
        cam_intrinsic = np.array([[f_x, 0, c_x], [0, f_y, c_y], [0, 0, 1]])
        
        return {
            "cam_to_world": cam_to_world,
            "cam_intrinsic": cam_intrinsic
        }

        
    @staticmethod
    def get_target_point_cloud(depth, cam_intrinsic, cam_extrinsic, mask, target_mask_label=(255,255,255)):
        h, w = depth.shape
        i, j = np.meshgrid(np.arange(w), np.arange(h), indexing='xy')
        
        z = depth
        x = (i - cam_intrinsic[0, 2]) * z / cam_intrinsic[0, 0]
        y = (j - cam_intrinsic[1, 2]) * z / cam_intrinsic[1, 1]
        
        points_camera = np.stack((x, y, z), axis=-1).reshape(-1, 3)
        points_camera_aug = np.concatenate([points_camera, np.ones((points_camera.shape[0], 1))], axis=-1)
        
        points_world = np.dot(cam_extrinsic, points_camera_aug.T).T[:, :3]
        mask = mask.reshape(-1, 3)
        target_mask = np.all(mask == target_mask_label, axis=-1)
        return {
            "points_world": points_world[target_mask],
            "points_camera": points_camera[target_mask]
        }
        
    @staticmethod
    def get_target_point_cloud(depth, cam_intrinsic, cam_extrinsic, mask, target_mask_label=(255,255,255)):
        h, w = depth.shape
        i, j = np.meshgrid(np.arange(w), np.arange(h), indexing='xy')
        
        z = depth
        x = (i - cam_intrinsic[0, 2]) * z / cam_intrinsic[0, 0]
        y = (j - cam_intrinsic[1, 2]) * z / cam_intrinsic[1, 1]
        
        points_camera = np.stack((x, y, z), axis=-1).reshape(-1, 3)
        points_camera_aug = np.concatenate([points_camera, np.ones((points_camera.shape[0], 1))], axis=-1)
        
        points_world = np.dot(cam_extrinsic, points_camera_aug.T).T[:, :3]
        mask = mask.reshape(-1, 3)
        target_mask = np.all(mask == target_mask_label, axis=-1)
        return {
            "points_world": points_world[target_mask],
            "points_camera": points_camera[target_mask]
        }
        
    @staticmethod
    def get_point_cloud_world_from_path(path):
        cam_info = DataLoadUtil.load_cam_info(path)
        depth = DataLoadUtil.load_depth(path)
        mask = DataLoadUtil.load_seg(path)
        point_cloud = DataLoadUtil.get_target_point_cloud(depth, cam_info['cam_intrinsic'], cam_info['cam_to_world'], mask)
        return point_cloud['points_world']
    
    @staticmethod
    def get_point_cloud_list_from_seq(root, seq_idx, num_frames):
        point_cloud_list = []
        for idx in range(num_frames):
            path = DataLoadUtil.get_path(root, seq_idx, idx)
            point_cloud = DataLoadUtil.get_point_cloud_world_from_path(path)
            point_cloud_list.append(point_cloud)
        return point_cloud_list