readField

Read point cloud data based on field name

Syntax

fielddata = readField(pcloud,fieldname)

Description

example

fielddata = readField(pcloud,fieldname) reads the point field from the PointCloud2 object, pcloud, specified by fieldname and returns it in fielddata. If fieldname does not exist, the function displays an error. To preserve the structure of the point cloud data, see Preserving Point Cloud Structure.

Examples

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Load sample ROS messages including a ROS point cloud message, ptcloud.

exampleHelperROSLoadMessages

Read the 'x' field name available on the point cloud message.

x = readField(ptcloud,'x');

Input Arguments

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Point cloud, specified as a PointCloud2 object handle 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 is a point cloud reading, where n is the number of points and c is the number of values for each point. If the point cloud object being read has the PreserveStructureOnRead property set to true, the points are returned as an h-by-w-by-c matrix. For more information, see Preserving Point Cloud Structure.

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 (readXYZ,readRGB, or readField) 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 only be preserved if the point cloud is organized.

Introduced in R2015a