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rosReadField

Read point cloud data based on field name

Description

fielddata = rosReadField(pcloud,fieldname) reads the point field from the PointCloud2 ROS or ROS 2 message, pcloud, specified by fieldname and returns it in fielddata.

fielddata = rosReadField(pcloud,fieldname,"PreserveStructureOnRead",true) preserves the organizational structure of the point cloud field data returned in the fielddata output. For more information, see Preserving Point Cloud Structure.

Input Arguments

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Point cloud, specified as a PointCloud2 message structure for a 'sensor_msgs/PointCloud2' ROS message.

Field name of point cloud data, specified as a string scalar or character vector. This string must match the field name exactly. If fieldname does not exist, the function displays an error.

Output Arguments

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List of field values from point cloud, returned as a matrix. Each row of the matrix is a point cloud reading, where n is the number of points and c is the number of values for each point.

If the PreserveStructureOnRead name-value pair argument is set to true, the points are returned as an h-by-w-by-c matrix.

Tips

Point cloud data can be organized in either 1-D lists or in 2-D image styles. 2-D image styles usually come from depth sensors or stereo cameras. The input PointCloud2 object contains a PreserveStructureOnRead property that is either true or false (default). Suppose you set the property to true.

pcloud.PreserveStructureOnRead = true;

Now calling any read functions (rosReadXYZ, rosReadRGB, or rosReadField) preserves the organizational structure of the point cloud. When you preserve the structure, the output matrices are of size m-by-n-by-d, where m is the height, n is the width, and d is the number of return values for each point. Otherwise, all points are returned as a x-by-d list. This structure can be preserved only if the point cloud is organized.

Extended Capabilities

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

Introduced in R2021a