removeHiddenPoints

Remove hidden points from point cloud

Since R2023a

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    Syntax

    ptCloudOut = removeHiddenPoints(ptCloudIn,viewPoint)
    ptCloudOut = removeHiddenPoints(ptCloudIn,viewPoint,RadiusScale=rScale)
    [ptCloudOut,indices] = removeHiddenPoints(___)

    Description

    ptCloudOut = removeHiddenPoints(ptCloudIn,viewPoint) removes hidden points from the point cloud ptCloudIn. The function removes the points hidden when viewing the point cloud from the specified viewpoint viewPoint. Determining the visibility of a point can be useful for shadow casting, reconstruction, and camera placement.

    example

    ptCloudOut = removeHiddenPoints(ptCloudIn,viewPoint,RadiusScale=rScale) specifies the radius scale of the spherical projection.

    [ptCloudOut,indices] = removeHiddenPoints(___) returns the indices of the points visible from the specified viewpoint, using any combination of input arguments from previous syntaxes.

    Examples

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    Open Live Script

    Read point cloud data from a PLY file into the workspace.

    ptCloud = pcread("teapot.ply");

    Define the viewpoint.

    viewPosition = [0 0 13];

    Compute the indices of the visible points in the point cloud from the specified viewpoint, and remove the hidden points.

    [ptCloudOut,indices] = removeHiddenPoints(ptCloud,viewPosition);

    Display the visible points.

    pcshow(ptCloudOut)
campos(viewPosition)

    Figure contains an axes object. The axes object contains an object of type scatter.

    Input Arguments

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    Input point cloud, specified as a pointCloud object.

    Viewpoint, specified as a three-element vector of the form [x y z]. Viewpoint can be inside or outside the point cloud.

    Data Types: single | double

    Radius scale of the spherical projection, specified as a positive scalar. The function scales the radius to a value of 10n, where n is the value of rScale. Increasing the radius scale increases the number of visible points.

    Note

    Specify a higher radius scale value for dense point clouds.

    Data Types: single | double

    Output Arguments

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    Output point cloud, returned as a pointCloud object.

    Indices of the points visible from the specified viewpoint, returned as an M-element column vector. M is the number of visible points.

    Algorithms

    The function uses these steps to determine the visible points in a point cloud from a specified viewpoint.

    1. Associate the point cloud with a coordinate system whose center lies at the viewpoint.

    2. Perform inversion using spherical projection.

      1. Create a sphere of radius R such that all points in the point cloud lie within the sphere. You can control the radius value by using the rScale input.

      2. Transform the point cloud by reflecting each point, with respect to the sphere, along the line joining the point and the viewpoint.

    3. Calculate a convex hull of the transformed point cloud and the viewpoint. The points inside the convex hull are the visible points.

    Extended Capabilities

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    C/C++ Code Generation
    Generate C and C++ code using MATLAB® Coder™.

    Version History

    Introduced in R2023a

    See Also

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