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docs: reflect camera frame configuration changes

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Oleg Kalachev
2020-04-30 05:03:29 +03:00
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docs/en/camera_setup.md
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@@ -1,10 +1,10 @@
# Camera setup
> **Note** The following applies to [image version](image.md) **0.15** and up. See [previous version of the article](https://github.com/CopterExpress/clover/blob/v0.14/docs/ru/camera_frame.md) (Russian only) for older images.
> **Note** The following applies to [image version](image.md) **0.20** and up. See [previous version of the article](https://github.com/CopterExpress/clover/blob/v0.19/docs/en/camera_frame.md) for older images.
Computer vision modules (like [ArUco markers](aruco.md) and [Optical Flow](optical_flow.md)) require adjusting the camera focus and set up camera position and orientation relative to the drone body.
Computer vision modules (like [ArUco markers](aruco.md) and [Optical Flow](optical_flow.md)) require adjusting the camera focus and set up camera position and orientation relative to the drone body. Optional camera calibration can improve their quality of performance.
## Focusing the camera lens
## Focusing the camera lens {#focus}
In order to focus the camera lens, do the following:
@@ -19,10 +19,71 @@ In order to focus the camera lens, do the following:
## Setting the camera position {#frame}
Position and orientation of the main camera is [set in the](cli.md#editing) `~/catkin_ws/src/clever/clever/launch/main_camera.launch` file:
Position and orientation of the main camera is [set in the](cli.md#editing) `~/catkin_ws/src/clover/clover/launch/main_camera.launch` file:
```xml
<node pkg="tf2_ros" type="static_transform_publisher" name="main_camera_frame" args="0 0 -0.07 -1.5707963 0 3.1415926 base_link main_camera_optical"/>
<arg name="direction_z" default="down"/> <!-- direction the camera points: down, up -->
<arg name="direction_y" default="backward"/> <!-- direction the camera cable points: backward, forward -->
```
To set the orientation, define:
* direction the camera lens points `direction_z`: `down` or `up`;
* direction the camera cable points `direction_y`: `backward` or `forward`.
### Examples
### Camera faces downward, cable goes backward
```xml
<arg name="direction_z" default="down"/>
<arg name="direction_y" default="backward"/>
```
<img src="../assets/camera_option_1_rviz.png" width=300>
<img src="../assets/camera_option_1_clever.jpg" width=300>
### Camera faces downward, cable goes forward
```xml
<arg name="direction_z" default="down"/>
<arg name="direction_y" default="forward"/>
```
<img src="../assets/camera_option_2_rviz.png" width=300>
<img src="../assets/camera_option_2_clever.jpg" width=300>
### Camera faces upward, cable goes backward
```xml
<arg name="direction_z" default="up"/>
<arg name="direction_y" default="backward"/>
```
<img src="../assets/camera_option_3_rviz.png" width=300>
<img src="../assets/camera_option_3_clever.jpg" width=300>
### Camera faces upward, cable goes forward
```xml
<arg name="direction_z" default="up"/>
<arg name="direction_y" default="forward"/>
```
<img src="../assets/camera_option_4_rviz.png" width=300>
<img src="../assets/camera_option_4_clever.jpg" width=300>
> **Hint** The [`selfcheck.py` utility](selfcheck.md) will describe your current camera setup in a human-readable fashion. Be sure to check whether this description corresponds to your actual camera position.
### Custom camera position
It's possible to set arbitrary camera position and orientation. In order to do that uncomment node, marked as `Template for custom camera orientation`:
```xml
<!-- Template for custom camera orientation -->
<!-- Camera position and orientation are represented by base_link -> main_camera_optical transform -->
<!-- static_transform_publisher arguments: x y z yaw pitch roll frame_id child_frame_id -->
<node pkg="tf2_ros" type="static_transform_publisher" name="main_camera_frame" args="0.05 0 -0.07 -1.5707963 0 3.1415926 base_link main_camera_optical"/>
```
This line describes how the camera is positioned relative to the drone body. Technically, it creates a static transform between the `base_link` frame ( which [corresponds to the flight controller housing](frames.md)) and the camera (`main_camera_optical`) in the following format:
@@ -39,44 +100,6 @@ Camera frame (that is, [frame of reference](frames.md)) is aligned as follows:
Shifts are set in meters, angles are in radians. You can check the transform for correctness using [rviz](rviz.md).
## Presets for Clover
## Calibration {#calibration}
The presets for usual camera orientations are available in the `main_camera.launch` file. The images should help you choose the one that is right for you: the first one is how your drone will be displayed in [rviz](rviz.md), the second is how the camera is actually mounted on the drone.
### 1. Camera faces downward, cable goes backward
```xml
<node pkg="tf2_ros" type="static_transform_publisher" name="main_camera_frame" args="0.05 0 -0.07 -1.5707963 0 3.1415926 base_link main_camera_optical"/>
```
<img src="../assets/camera_option_1_rviz.png" width=400>
<img src="../assets/camera_option_1_clever.jpg" width=400>
### 2. Camera faces downward, cable goes forward
```xml
<node pkg="tf2_ros" type="static_transform_publisher" name="main_camera_frame" args="0.05 0 -0.07 1.5707963 0 3.1415926 base_link main_camera_optical"/>
```
<img src="../assets/camera_option_2_rviz.png" width=400>
<img src="../assets/camera_option_2_clever.jpg" width=400>
### 3. Camera faces upward, cable goes backward
```xml
<node pkg="tf2_ros" type="static_transform_publisher" name="main_camera_frame" args="0.05 0 0.07 1.5707963 0 0 base_link main_camera_optical"/>
```
<img src="../assets/camera_option_3_rviz.png" width=400>
<img src="../assets/camera_option_3_clever.jpg" width=400>
### 4. Camera faces upward, cable goes forward
```xml
<node pkg="tf2_ros" type="static_transform_publisher" name="main_camera_frame" args="0.05 0 0.07 -1.5707963 0 0 base_link main_camera_optical"/>
```
<img src="../assets/camera_option_4_rviz.png" width=400>
<img src="../assets/camera_option_4_clever.jpg" width=400>
> **Hint** The [`selfcheck.py` utility](selfcheck.md) will describe your current camera setup in a human-readable fashion. Be sure to check whether this description corresponds to your actual camera position.
To improve the quality of computer vision related algorithms it's recommended to perform camera calibration, which is described in the [appropriate article](camera_calibration.md).