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Description

This package stores object models and their information which can be used by other packages like object recognizers.

Samples of objects stored in the database:

Functionality

There are several services this package offers to access the object models which are stored in the rsc directory located at the base path of it. Inside this directory in /rsc/databases there are subdirectories which group the objects together based on their usage (mostly depending on the recognizer which is used to detect them in a scene). Take note that groups and their objects within can only be queried by services if they are declared in config.xml in the rcs directory. This doesn't apply for example to the environment objects, which are only used for visualization purposes by other packages; they can be accessed by specifying the path to them directly without any service call.

Each object is represented as a folder, the (unique) name of the folder being the one of the object, and at least a mesh file inside of it. In addition there can/should be more information stored inside, for example the object's normal vectors (by default stored as a file ending with .nv.txt) which describe the orientations from where the object is best visible (usually created with this package's normal generator tool; check the provided tutorial for more information) or a file containing information about how large a recognizer's uncertainty concerning the object is allowed to be (by default stored as a file ending with .dev.txt). If those files don't exist but are needed when a service regarding those is called, they are created with default values and should be adjusted accordingly.

Usage

Needed packages

• asr_ros_uri

• asr_xsd2cpp

• assimp_devel

Needed software

• xsdcxx
• libxerces

Start system

To start this package simply run

rosrun asr_object_database asr_object_database

After this you can call a service of your choice to query the objects stored in this package.

ROS Nodes

Provided Services

Several services are provided to query the database and get information about the objects within:

• object_meta_data: Returns information about a specific object

  • Parameters:

    • object_type (string): The name of the object (see object_type_list)

    • recognizer (string): The name of the recognizer used to detect the object in a scene (see recognizer_list)

  • Returns:

    • object_folder (string): The path to the directory containing the files of this object as a package-url (see resource_retriever for more information)

    • object_mesh_resource (string): The path to this object's mesh file as a package-url
    • normal_vectors (geometry_msgs/Point[]): A list of normals representing the orientations the object can be detected the best from
    • deviations (float64[]): A list of deviation values describing a recognizer's possible uncertainty about this object
    • is_valid (bool): If this is false, then there is no object in the database with the given name and recognizer
    • is_rotation_invariant (bool): If this is false, then the object can be rotated around at least on axis by certain degrees without changing its geometrical view (e.g. a cylindrical object)

• recognizer_list: Returns all available recognizer categories (which contain objects)

  • Parameters: -
  • Returns:
    • recognizer_list (string[]): A list of names of the available recognizers

• object_type_list: Returns the objects of a given recognizer category

  • Parameters:

    • recognizer (string): The name of the recognizer to query for objects (see recognizer_list)

  • Returns:
    • object_type_list (string[]): A list of names of the objects the given recognizer category contains

• recognizer_list_meshes: Returns a list of paths to the mesh files of all objects in a given recognizer category

  • Parameters:
    • recognizer (string): The name of the recognizer category to query
  • Returns:
    • meshes (string[]): A list of paths (as package-urls) to the mesh files of the given category

• generate_object_type: Generates an entry (folder, meta information and Collada-mesh-file) in the database for a given textured object (Currently the conversion of the mesh file does not work properly but can be done manually with meshlab for example)

  • Parameters:

    • sourcefile (string): A file path to a mesh which has to end with "_tex.obj". There also have to be a .mtl and a .png file in the same directory.

  • Returns: -

Tutorials

Generate normals for an object