# Single camera

This guide provides instructions on how to launch the camera node with a colored point cloud feature enabled using ROS 2.

- Table of contents
  - [Start single camera](#start-single-camera)
  - [Visualizing data in rviz2](#visualizing-data-in-rviz2)
  - [Display view topics service](#display-view-topics-service)
  - [Example visualizations](#example-visualizations)
  - [TF tree diagram](#tf-tree-diagram)

## Start single camera

For how to compile and build methods, please refer to Chapter `Installation/Build_the_package `documentation and follow the steps provided
[build_the_package](../2_installation/build_the_package.md)

- Command to start single camera node

On terminal 1: Launch camera node, example of gemini330 series :

```bash
cd ~/ros2_ws/
source /opt/ros/$ROS_DISTRO/setup.bash
source install/setup.bash
ros2 launch orbbec_camera orbbec_camera.launch.py config_file_path:=gemini330_series.yaml
```

config_file_path:=gemini330_series.yaml means orbbec_camera.launch.py uses the parameters set in gemini330_series.yaml

## Launch parameters

For the definition and function of launch parameters, please refer to common.yaml. All open parameters are in common.yaml.The following is a partial common.yaml display:

```yaml
# config/*.yaml files are used to configure the camera parameters
---
orbbec_ros:
    camera_parameters:
        general:
            # Camera model. upport product models by referencing config/*.yaml
            camera_model: "gemini330_series"
            # The configuration file for yaml params.
            config_file_path: "gemini330_series.yaml"
            # Log level. Supported levels are 'debug', 'info', 'warning' and 'error'. Default is 'none'.
            log_level: "none"

        deivce:
            # camera name, usually overwritten by launch file
            camera_name: "camera"
            # camera serial number, usually overwritten by launch file
            serial_number: ""
            # The USB port of the camera. This parameter is required when using multiple cameras.
            usb_port: ""
            # Number of devices. If multiple cameras are required, this parameter must be filled in launch file
            device_num: 1
            # Optional values: v4l2, libuvc
            uvc_backend: "libuvc"
            # Usually no need to change
            vendor_id: "0x2bc5"
```

Notice:If you run orbbec_camera.launch.py, the default combination of launch parameters used is common.yaml+gemini330_series.yaml, and the parameters in gemini330_series.yaml have higher priority than common.yaml

## Visualizing data in rviz2

- view_display launch

`view_display.launch.py` supports loading different `.rviz` files through yaml configuration. For example, loading the default `.rviz` file to display four streams.  config in different `.model.yaml `files through yaml configuration.

On terminal 2:

```bash
cd ~/ros2_ws/
source /opt/ros/$ROS_DISTRO/setup.bash
source install/setup.bash
ros2 launch orbbec_description view_display.launch.py camera_model:=gemini335_336
```

![view_display_gemini335_336](../image/view_display_gemini335_336.png)

- view_model launch

`view_model.launch.py` supports loading different `.model.yaml `files through yaml configuration. For example, loading the default model file to display gemini335_336 model .

On terminal 3:

```bash
cd ~/ros2_ws/
source /opt/ros/$ROS_DISTRO/setup.bash
source install/setup.bash
ros2 launch orbbec_description view_model.launch.py camera_model:=gemini335_336
```

![view_model_gemini335_336](../image/view_model_gemini335_336.png)

- Or you can run rviz2 and configure it  by yourself

```bash
cd ~/ros2_ws/
source /opt/ros/$ROS_DISTRO/setup.bash
source install/setup.bash
rviz2
```

When runing rviz2, select the topic you wish to visualize from the list of published topics.
Add the selected topic to rviz2 to start viewing the data.

## Display view topic/service/param

Once the camera node is running, it will publish data on several ROS topics. Below is a list of the available topics:
By executing `ros2 topic list`, the following topics are displayed:

On terminal 4:

```bash
ros2 topic list
```

Other , to display services/ parameters , example as follows

```bash
ros2 service list
ros2 param list
```

Get device info:

```bash
ros2 service call /camera/get_device_info orbbec_camera_msgs/srv/GetDeviceInfo '{}'
```

Get SDK version:

```bash
ros2 service call /camera/get_sdk_version orbbec_camera_msgs/srv/GetString '{}'
```

Set auto exposure:

```bash
ros2 service call /camera/set_color_auto_exposure std_srvs/srv/SetBool '{data: false}'
```

Save point cloud:

```bash
ros2 service call /camera/save_point_cloud std_srvs/srv/Empty "{}"
```

 

## Example visualizations

Here are examples of how the visualization might appear in rviz2:

- **PointCloud Visualization**

![PointCloud View](../image/image1.jpg)

 

- **Image Data Visualization**

![Image Data View](../image/image2.jpg)

 

## Aligning Depth to Color

### Commands to Align and View Depth and Color Images

1. **Basic Depth to Color Alignment:**
   To simply align the depth image to the color image, use the following command:

   ```shell
   ros2 launch orbbec_camera gemini_330_series.launch.py depth_registration:=true
   ```

   This command activates the depth registration feature without opening a viewer.
2. **Viewing Depth to Color Overlay:**
   If you wish to view the depth to color overlay, you need to enable the viewer by using the command below:

   ```shell
   ros2 launch orbbec_camera gemini_330_series.launch.py depth_registration:=true enable_d2c_viewer:=true
   ```

   This launches the camera node with depth to color registration and opens a viewer to display the overlay image.

### Selecting Topics in RViz2

To visualize the aligned images in RViz2:

1. Launch RViz2 after running one of the above commands.
2. Select the topic for the depth to color overlay image. An example topic selection is shown here:

![D2C topic](../image/image3.png)

### Example of Depth to Color Overlay

After selecting the appropriate topic in RViz2, you will be able to see the depth to color overlay image. Here's what it might look like:

![D2C VIEW](../image/image4.jpg)

## Enabling and Visualizing Point Cloud

### Enabling Depth Point Cloud

#### Command to Enable Depth Point Cloud

To activate the point cloud data stream for depth information, use the following command:

```shell
ros2 launch orbbec_camera gemini_330_series.launch.py enable_point_cloud:=true
```

#### Visualizing Depth Point Cloud in RViz2

After running the above command, perform the following steps to visualize the depth point cloud:

1. Open RViz2.
2. Add a `PointCloud2` display.
3. Select the `/camera/depth/points` topic for visualization.
4. Set the fixed frame to `camera_link` to properly align the data

#### Example Visualization

Here is what the depth point cloud might look like in RViz2:

![Depth Point VIEW](../image/image5.jpg)

### Enabling Colored Point Cloud

#### Command to Enable Colored Point Cloud

To enable the colored point cloud feature, enter the following command:

```shell
ros2 launch orbbec_camera gemini_330_series.launch.py enable_colored_point_cloud:=true
```

#### Visualizing Colored Point Cloud in RViz2

To visualize the colored point cloud data:

1. Launch RViz2 following the command execution.
2. Add a `PointCloud2` display panel.
3. Choose the `/camera/depth_registered/points` topic from the list.
4. Ensure the fixed frame is set to `camera_link`.

#### Example Visualization

The result of the colored point cloud in RViz2 should look similar to this:

![Color Point VIEW](../image/image6.jpg)

## TF tree diagram

To get the TF tree

```bash
ros2 run rqt_tf_tree rqt_tf_tree --force-discover
```

 

The TF tree diagram for the OrbbecSDK_ROS2 is illustrated below:
![single_cam_tf.png](../image/single_cam_tf.png) `<!-- docs/source/3_start_single_camera/start_single_camera.md -->`