Rendering Multi-View Images for 3D Point Cloud using MeshLab

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    # 把 .bin 文件转换成 .ply，除了点坐标，点云坐标带法向量

    import os
    import struct
    import numpy as np
    from plyfile import PlyData, PlyElement

    def convert_bin_to_ply(bin_file, ply_file):
        count = 0
        with open(bin_file, 'rb') as f:
            while True:
                if count == 0:
                    # NOTE please refer to the github repository of scanobjectnn to check the format of .bin file 
                    # according to the scanobjectnn, the first number in .bin is `the number of points` in `float32` format, which has 4 bytes
                    data = f.read(4)
                    npoints = struct.unpack('f', data)  # `npoints` is a tuple, which has one element

                    vertex = np.zeros(int(npoints[0]), dtype=[('x', 'f4'), ('y', 'f4'), ('z', 'f4')])
                    x_coors, y_coors, z_coors = [], [], []
                    nx, ny, nz = [], [], []
                    count = 1
                    continue

                else:
                    # according to the scanobjectnn, the following numbers in .bin are 11 `float32` numbers, which has 44 bytes
                    data = f.read(44)

                    if len(data) != 44:
                        break
                    point = struct.unpack('fffffffffff', data)
                    x_coors.append(point[0])
                    y_coors.append(point[1])
                    z_coors.append(point[2])
                    nx.append(point[3])
                    ny.append(point[4])
                    nz.append(point[5])

        x = np.array(x_coors)
        y = np.array(y_coors)
        z = np.array(z_coors)
        nx = np.array(nx)
        ny = np.array(ny)
        nz = np.array(nz)

        vertex = np.core.records.fromarrays([x, y, z, nx, ny, nz],
                                            names='x, y, z, nx, ny, nz',
                                            formats='f4, f4, f4, f4, f4, f4')

        vertex_element = PlyElement.describe(vertex, 'vertex')

        # Create the PlyData object with the vertex element
        plydata = PlyData([vertex_element])

        # Write the PlyData to the .ply file
        plydata.write(ply_file)

        print(f'Conversion complete. {bin_file} converted to {ply_file}.')

    if '__main__' == __name__:
        data_dir  = '/mnt/sdb/public/data/common-datasets/ScanObjectNN_3_variants'
        ply_dir = '/mnt/sdb/public/data/common-datasets/ScanObjectNN_plyn_files'

        for cls in os.listdir(data_dir):
            cls_dir = os.path.join(data_dir, cls)
            if os.path.isdir(cls_dir):
                for f in os.listdir(cls_dir):
                    if f.endswith('.bin') and '_part' not in f and '_indices' not in f:
                        bin_file = os.path.join(cls_dir, f)
                        fname = f.split('.')[0]
                        ply_file = os.path.join(ply_dir, f'{fname}.ply')
                        
                        convert_bin_to_ply(bin_file, ply_file)
    

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    #!/bin/bash

    # Input directory containing PLY files
    ply_directory="ScanObjectNN_plyn_files"

    # Output directory for reconstructed PLY files
    reconstructed_directory="ScanObjectNN_plyn_files_recon"

    # Output directory for OBJ files
    obj_directory="ScanObjectNN_obj_files"

    # Iterate over the PLY files
    for ply_file in "$ply_directory"/*.ply; do
        # Set up output file paths
        filename=$(basename "$ply_file")
        base_name="${filename%.*}"
        reconstructed_ply_file="$reconstructed_directory/$base_name.ply"
        obj_file="$obj_directory/$base_name.obj"

        # Reconstruct surface using meshlabserver
        meshlabserver -i "$ply_file" -o "$reconstructed_ply_file" -s poisson_surface_reconstruct.mlx

        # Convert reconstructed PLY to OBJ using meshlabserver
        meshlabserver -i "$reconstructed_ply_file" -o "$obj_file"

        echo "Converted: $ply_file -> $obj_file"
    done