Note: This tutorial assumes you have already created your own URDF file or that you are working with the existing PR2 URDF file.

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Exporting URDF to COLLADA

Description: This tutorial teaches you how to export an URDF file to a COLLADA document

Tutorial Level: BEGINNER

Contents

Building collada_urdf
Using in your code

Building collada_urdf

$ rosdep install collada_urdf

This will install all the external dependencies for collada_urdf. To build the package, run:

$ rosmake collada_urdf

Using in your code

First, add the package as a dependency to your manifest.xml file:

<package>
    ...
    <depend package="collada_urdf" />
    ...
</package>

To start using the exporter in your C++ code, include the following file:

   1 #include <collada_urdf/collada_urdf.h>
   2

Now there are different ways to proceed. You can construct a COLLADA Document Object Model (DOM) from URDF in a variety of ways:

From a file

   1 boost::shared_ptr<DAE> dom;
   2 if (!collada_urdf::colladaFromUrdfFile("filename.urdf", dom)) {
   3     ROS_ERROR("Failed to construct COLLADA DOM");
   4     return false;
   5 }

To create the PR2 URDF file, run the following command:

$ rosrun xacro xacro.py `rospack find pr2_description`/robots/pr2.urdf.xacro > pr2.urdf

From the parameter server

   1 boost::shared_ptr<DAE> dom;
   2 ros::NodeHandle node;
   3 std::string robot_desc_string;
   4 node.param("robot_description", robot_desc_string, std::string());
   5 if (!collada_urdf::colladaFromUdfString(robot_desc_string, dom)) {
   6     ROS_ERROR("Failed to construct COLLADA DOM");
   7     return false;
   8 }

From an XML document

   1 boost::shared_ptr<DAE> dom;
   2 TiXmlDocument xml_doc;
   3 xml_doc.Parse(xml_string.c_str());
   4 xml_root = xml_doc.FirstChildElement("robot");
   5 if (!xml_root) {
   6     ROS_ERROR("Failed to find robot element in XML document");
   7     return false;
   8 }
   9 if (!collada_urdf::colladaFromUrdfXml(xml_root, dom)) {
  10     ROS_ERROR("Failed to construct COLLADA DOM");
  11     return false;
  12 }

From an URDF model

   1 boost::shared_ptr<DAE> dom;
   2 urdf::Model my_model;
   3 if (!my_model.initXml(....)) {
   4     ROS_ERROR("Failed to parse URDF robot model");
   5     return false;
   6 }
   7 if (!collada_urdf::colladaFromUrdfModel(my_model, dom)){
   8     ROS_ERROR("Failed to construct COLLADA DOM");
   9     return false;
  10 }

Writing COLLADA to file

Once you have your COLLADA document loaded, you can write the document to a file:

   1 collada_urdf::colladaToFile(dom, "filename.dae");

For more details, take a look at the API documentation.

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