error: ‘ExtractIndices’ is not a member of ‘pcl’

This error message means that the compiler is unable to find the definition of the function or class called "ExtractIndices" within the "pcl" namespace. There could be several reasons for this error, such as:

1. The function or class definition may not be included in the header files or libraries that are being used in the program.
2. The function or class definition may be misspelled or named differently.
3. The function or class definition may be defined in a different namespace.

To resolve this error, you can try the following steps:

1. Check if the function or class definition is included in the header files or libraries that you are using in your program.
2. Check if the function or class name is spelled correctly and matches the definition.
3. Check if the function or class is defined in a different namespace and use the appropriate namespace prefix to access it.

If none of these steps work, you may need to consult the documentation or seek help from the community or support team for the library or framework that you are using.