matlab软件pointcloud工具——pointCloud生成点云功能

  写在最前边，这是对于Point cloud tools for Matlab网页的整理
  https://www.geo.tuwien.ac.at/downloads/pg/pctools/pctools.html#PointCloud_class原网页

  pointCloud Import of point cloud data.                                  //输入点云数据，其实是生成点云的功能，主要包含三部分1、输入2、属性3、输出
  ----------------------------------------------------------------------工作区有这个就表示生成了点云文件
  DESCRIPTION/NOTES        
  This function creates an object instance of the pointCloud class. For
  a listing of available attributes and methods for the pointCloud class
  run 'doc pointCloud'.
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  INPUT                                                                    //输入  主要是这两种pc=pcCloud（[x y z]）和pc=pcCloud（‘文件名.xyz’）
  1 [pcData]                                                               //例如pcCloud（[x y z]）就可以直接生成点云
    Point cloud input data defined as:                                     //通过文件路径输入
    a PATH TO A POINT CLOUD FILE
      Absolute or relative path to a:
      1 PLAIN TEXT FILE                                                   //纯文本格式.txt文件
                                                                          //pcCloud（‘文件名.xyz’）是可以直接使用，直接生成点云
        Column oriented text file where each row correspondonds to one    //所以其他格式例如asc要么要转格式，要么就要添加其他功能包
        point. The first 3 columns contain the point coordinates x, y     //dlmread可以读取asc格式文件，然后再用save保存为xyz格式就行
        and z. Further columns can be used for point attributes (e.g.     //其他格式转换也类似
        color values r, g and b). Two possibilities exist to define the
        names of the attributes:
          * by using the parameter 'Attributes' (see below) 
          * by defining the attribute names in the first line of the
            file using the following format: 
            '# columns: x y z attributeName1 attributeName2 ...'
      2 BINARY FILE
        In binary files all values have to be stored in double precision
        (i.e. 8 bytes per value). All values are stored sequentially
        (e.g. for two points with one attribute the ordering would be
        x1, y1, z1, a1, x2, y2, z2, a2).
      3 LAS/LAZ FILE
        For reading las or laz files the function 'las2mat' must be
        accessible on the path. It can be downloaded here:
        https://github.com/plitkey/matlas_tools
      4 ODM FILE
        Files created with OPALS (http://geo.tuwien.ac.at/opals). For
        this it is necessary to:
        1) Install OPALS
        2) Add '%opals_root%\opals' to the search path in Matlab.
        Note: with the 'Filter' parameter, an odm filter string can be 
        applied during the import.
      5 PLY FILE
        Polygon file format, either in ascii or binary format.
      6 MAT FILE
        This method can also be used to load a mat file generated with
        the 'save' method of this class. For more details run
        'help pointCloud.save'.
    b MATRIX CONTAINING POINT CLOUD DATA                                    //数组生成点云，最少三列表示xyz坐标
      A matrix of size n-by-3+a. Each row corresponds to one point, i.e.
      n is the total number of points. The first 3 columns contain the
      point coordinates x, y and z. Further columns can be used for
      point attributes (e.g. color values r, g and b). To import these
      attributes the parameter 'Attributes' has to be defined (see
      below).
 
  2 ['Attributes', attributes]                                             //常见的属性 nx，ny，nz是方向向量，r、g、b是颜色，roughness是粗糙度
    Name of attributes contained in input data defined as 1-by-a cell,
    where a denotes the number of attributes. Predefined attribute names
    to use for extended functionality:
      * 'nx'        = normal x component
      * 'ny'        = normal x component
      * 'nz'        = normal z component
      * 'r'         = color red component
      * 'g'         = color green component
      * 'b'         = color blue component
      * 'roughness' = roughness in point neighborhood
    Imported attributes are saved into the property A of the pointCloud    //数据的参数是保存在点云中的
    object, i.e. obj.A.
    Additionally, for LAS/LAZ, ODM and PLY files the following applies:
    - If the parameter 'Attributes' is not defined by the user, all 
      non-empty attributes are imported.
    - If the name of one or more attribute is specified by the parameter
      'Attributes', only these are imported.
    - If the parameter 'Attributes' is set to an empty cell, i.e. {}, NO
      attributes are imported.
 
  3 ['Label', label]                                                      //点云的名字
    Label of point cloud defined as a string. If no label is defined and
    input is a file path, the file name is used as label.
 
  4 ['RedPoi', redPoi]
    Coordinate reduction point defined as vector with 3 elements. The     //坐标原点位置
    reduction point defines the origin of a local coordinate system in
    which the points are stored.
 
  5 ['HeaderLines', headerLines]
    Number of header lines (=rows) to be skipped, if a plain text file
    is used as point cloud input.
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  OUTPUT
  1 [obj]
    Object instance of class pointCloud.
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  EXAMPLES                                                                    //1、显示狮子的点云2、三角龙点云3、均匀分布的球体点云
  1 Import a point cloud without attributes.
    pc = pointCloud('Lion.xyz');
    pc.plot;
 
  2 Import a point cloud with attributes.
    pc = pointCloud('Gieszkanne.xyz', 'Attributes', {'r' 'g' 'b'});
    % Attributes are now accessible in the object property pc.A
    pc.plot('Color', 'rgb', 'MarkerSize', 5);
 
  3 Import a point cloud from a matrix.
    [x, y, z] = sphere(100);
    x = x(:); y = y(:); z = z(:);
    pc = pointCloud([x y z], 'Label', 'sphere');
    pc.plot('MarkerSize', 5);
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