# Viewing images from cameras

To view images from cameras (or other ROS topics), you can use [rviz](rviz.md), rqt, or watch them in a browser using web\_video\_server.

See read more about [using rqt](rviz.md).

## Viewing in a browser

### Configuration

Make sure that in Clever launch-file \(`~/catkin_ws/src/clever/clever/launch/clever.launch`\), starting `web_video_server` is enabled:

```xml
<arg name="web_video_server" default="true"/>
```

After the launch-file is edited, restart package `clever`:

```bash
sudo systemctl restart clever
```

### Viewing

To view a video-stream, you have to [connect to Wi-Fi](Wi-Fi.md) of Clever \(`CLEVER-xxxx`\), navigate to page [http://192.168.11.1:8080/](http://192.168.11.1:8080/), and choose the topic.

![Viewing web_video_server](../assets/web_video_server.png)

If the image is transmitted too slow, you can speed it up by changing GET parameter `quality` (from 1 to 100), which is responsible for video-stream compression, for example:

http://192.168.11.1:8080/stream_viewer?topic=/main_camera/image_raw&quality=1

At the URL above, a stream from the main camera will be available in the minimum possible quality.

Parameters `width`, `height`, etc. re also available. Read more about `web_video_server`: http://wiki.ros.org/web_video_server.

## Browse with rqt_image_view

To browse images with the rqt tools the user needs a computer with Ubuntu 16.04 и [ROS Kinetic](http://wiki.ros.org/kinetic/Installation/Ubuntu).

[Connect to the Clever Wi-Fi network](wifi.md) an run `rqt_image_view` with its IP-address:

```bash
ROS_MASTER_URI=http://192.168.11.1:11311 rqt_image_view
```

Choose a topic for browsing, for example `/main_camera/image_raw`:

![rqt_image_view](../assets/rqt_image_view.jpg)

To reduce network load and reduce latency, use a compressed version of the topic – `/main_camera/image_raw/compressed`.

To change the compression settings use the rqt-plugin Dynamic Reconfigure:

![rqt_image_view+rqt_dynamic_reconfigure](../assets/rqt_image_view_dyn_rec.jpg)

Refer to [more about rviz and rqt](rviz.md).