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Description

This Package contains a library which is used to convert point clouds and images between ROS and HALCON specific data structures.

Functionality

The structure of this library is mostly based on the cv_bridge-package, for more information you can check out the documentation for that.

Usage

Needed packages

The package itself does not have any dependencies on external ROS-packages (besides the default ones which come with the core installation of ROS).

Needed software

To be able to build this package and use it in your project you will need to have a version of the HALCON image processing library installed. So far it was tested mainly with version 11 but in theory it should work with higher versions as well as the basic structure of the data types has not changed (build tests have been conducted with version 12 as well).

The environment variables HALCONROOT and HALCONARCH need to be set correctly, otherwise cmake won't be able to find your HALCON installation. Usually this should be the case if you have followed the installation guide of HALCON.

Needed hardware

You need to have a valid license for your HALCON installation; if you obtained a usb-dongle for that reason you need to have it plugged in during runtime or you will receive an exception.

Start system

As this package only contains a library you should see 5. for more information on how to use it.

ROS Nodes

There are no subscribed/published topics or services and also no configuration parameters.

Tutorials

To use the functions offered by this library you need to set this package as a dependency for your project first and then include either halcon_image.h or halcon_pointcloud.h in your code depending on what you want to convert.

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Convert an image:

To convert a sensor_msgs::Image to a HalconCpp::HImage call one of the following functions:

HalconImagePtr toHalconCopy(const sensor_msgs::ImageConstPtr& source)
HalconImagePtr toHalconCopy(const sensor_msgs::Image& source);

The return-value is a HalconImagePtr object, which contains a HalconCpp::HImage-Pointer as a member called image.

To convert a HalconImage to ROS again call one of the following member functions:

sensor_msgs::ImagePtr toImageMsg() const;
void toImageMsg(sensor_msgs::Image& ros_image) const;

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Convert a point cloud:

This step is similar to the image conversion. The important functions are

HalconPointcloudPtr toHalconCopy(const sensor_msgs::PointCloud2ConstPtr& source);
HalconPointcloudPtr toHalconCopy(const sensor_msgs::PointCloud2& source);

to convert a sensor_msgs::PointCloud2 to a HalconCpp::HObjectModel3D (the member in the returned HalconPointcloud is called model).

To convert it back to ROS call:

sensor_msgs::PointCloud2Ptr toPointcloudMsg() const;
void toPointcloudMsg(sensor_msgs::PointCloud2& ros_pointcloud) const;