Reading input Error: "label" property not found in input file.

[wbq13599531791]

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Issue Details

我想用cgal中的classification算法对已经打好标签的ply数据做训练，但是无法读取ply数据到Point_set后，无法读取Point_set中的property_map(已经用CLoudCompare对ply文件添加了SF标签，起名为label)
Describe your issue. Please be specific (compilation error, runtime error, unexpected behavior, wrong results, etc.).

Source Code

int main(int argc, char** argv)
{
    std::string filename(argc > 1 ? argv[1] : CGAL::data_file_path("../data/in/Train-mesh.ply"));
    std::ifstream in(filename.c_str(), std::ios::binary);
    Point_set pts;
    std::cerr << "Reading input" << std::endl;
    in >> pts;
    /*for (int index_p = 0; index_p < pts.size(); index_p++)
    {
        std::cout << pts.normal(index_p) << std::endl;
    }*/
    Imap label_map;
    bool lm_found = false;
    std::string str("Colors");
    std::tie(label_map, lm_found) = pts.property_map<int>(str);

    if (!lm_found)
    {
        std::cerr << "Error: \"label\" property not found in input file." << std::endl;
        return EXIT_FAILURE;
    }
    std::cerr << "Generating features" << std::endl;
    CGAL::Real_timer t;
    t.start();
    Feature_set features;

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Environment

Win10,64bit
vs2019
Cmake
CGAL5.5.1

• Operating system (Windows/Mac/Linux, 32/64 bits):
• Compiler:
• Release or debug mode:
• Specific flags used (if any):
• CGAL version:
• Boost version:
• Other libraries versions if used (Eigen, TBB, etc.):

[sloriot]

Default operator>>() expect the mesh to be in OFF format. You should use the function CGAL::IO::read_PLY() directly and follow the doc to see how to have colors defined:
https://doc.cgal.org/latest/Surface_mesh/group__PkgSurfaceMeshIOFuncPLY.html#ga3b898d61ab5682756b25c425a8d8ec97