Index-based Point Cloud Selection

Functional Description

This operator is used to select one or more point clouds from an input list of point clouds (a data collection containing multiple point clouds) based on a specified index number. Users can accurately select a specific point cloud in the list by setting the index number, or retain all point clouds except the one specified by the index number using the reverse index function.

Usage Scenarios

  • Processing Multi-Point Cloud Input: When a preceding operator (such as point cloud clustering or multi-template matching) outputs a list containing multiple point clouds, this operator can be used to select a specific point cloud from it for subsequent processing. For example, selecting the first or last point cloud cluster from the clustering results.

  • Filtering Specific Point Clouds: When it is necessary to exclude a specific point cloud from the list, the reverse index function can be used. For example, removing the result point cloud with the lowest or highest matching score.

  • Flow Control: In complex algorithm flows, select a specific point cloud from the list for processing based on conditions.

Inputs and Outputs

Input Items

Pointcloud: A list containing one or more point clouds.

Output Items

List of point clouds indexed to: A list containing the selected point cloud(s).

Parameter Description

This operator has two versions:

  • Index-based Point Cloud Selection : Processes point clouds without normal information.

  • Index-based Point Cloud Selection(with Normals) : Processes point clouds with normal information.

Both have identical functionality and parameters, only differing in the type of point cloud data they process.

  • Index starts from 0: The first point cloud in the list has an index of 0, the second is 1, and so on.

  • -1 Index: -1 is a convenient shortcut to select the last element in the list without needing to know the exact length of the list beforehand.

  • Index Range: Ensure that the set "Index number" is within the valid range of the input point cloud list, otherwise an error will occur.

Index number

Parameter Description

Specifies the position number in the input list of the point cloud to be selected (or excluded when reverse indexing). Indexing starts from 0. A special value of -1 indicates the last point cloud in the list.

Tuning Description

  • Set to 0: Selects the 1st point cloud in the list.

  • Set to 1: Selects the 2nd point cloud in the list.

  • Set to -1: Selects the last point cloud in the list.

  • Set to other positive integer n: Selects the (n+1)th point cloud in the list.

  • Note: The set index number must be within the valid range (from -1 to list length - 1), otherwise the operator will report an error. For example, if the input list only has 3 point clouds, the valid index range is -1, 0, 1, 2.

Parameter Range

[-1, 10000], Default: 0, the actual upper limit depends on the length of the input list.

Reverse index

Parameter Description

Changes the selection logic of the operator.

Tuning Description

  • Disabled (default): Forward indexing, the operator only outputs the point cloud specified by the "Index number" parameter. The output list contains only one point cloud.

  • Enabled: The operator outputs all point clouds in the list except for the one specified by the "Index number" parameter. The output list contains a number of point clouds equal to the original list length minus one.