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New tutorial on track_visual #102

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14d9770
New tutorial on track_visual
parrotepicuser Jan 8, 2016
9561248
added to manifest
chapulina Jan 8, 2016
bdd01ac
Fixed indentation
parrotepicuser Jan 11, 2016
408ac89
Say "model origin" instead of "origin"
parrotepicuser Jan 11, 2016
fa92b63
Removed ~~~ when not needed
parrotepicuser Jan 11, 2016
27a331b
Use the sphere example
parrotepicuser Jan 11, 2016
dc851f1
Minor change
parrotepicuser Jan 11, 2016
08cb3cc
renamed relative to use_model_frame
parrotepicuser Jan 13, 2016
cf2d39f
added list of parameters
parrotepicuser Jan 13, 2016
6f59940
merge with d665c43
parrotepicuser Jan 13, 2016
faa5ce6
merge with ed4d18e
parrotepicuser Jan 13, 2016
555d0a3
merge with b628cac
parrotepicuser Jan 13, 2016
f32d0fb
new sphere example
parrotepicuser Jan 14, 2016
a4c63d4
fix sdf version
parrotepicuser Jul 12, 2017
c607aa6
change user camera pose to better visualize the scene
parrotepicuser Jul 12, 2017
e799c47
merge with default
parrotepicuser Jul 12, 2017
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7 changes: 7 additions & 0 deletions manifest.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -393,6 +393,12 @@
<skill>beginner</skill>
</tutorial>

<tutorial title="Tracking visuals" ref='track_visual'>
<markdown version="7.0+">track_visual/tutorial.md</markdown>
<description>Use the graphical interface or SDF files to track visuals with the user camera.</description>
<skill>beginner</skill>
</tutorial>

<tutorial title="Instrument HDF5 Datasets" ref='instrument_hdf5_datasets'>
<markdown version="1.9+">instrument_hdf5_datasets/tutorial.md</markdown>
<description>How to dump simulation data into HDF5 format for benchmark.</description>
Expand Down Expand Up @@ -1032,6 +1038,7 @@
<tutorial>log_filtering</tutorial>
<tutorial>apply_force_torque</tutorial>
<tutorial>instrument_hdf5_datasets</tutorial>
<tutorial>track_visual</tutorial>
</tutorials>
</category>

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102 changes: 102 additions & 0 deletions track_visual/files/track_visual.world
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@@ -0,0 +1,102 @@
<?xml version="1.0" ?>
<sdf version="1.6">
<world name="default">
<!-- A global light source -->
<include>
<uri>model://sun</uri>
</include>
<!-- A ground plane -->
<include>
<uri>model://ground_plane</uri>
</include>

<gui>
<camera name="user_camera">
<pose>-2 0 2 0 0 0</pose>
<track_visual>
<name>box</name>
<static>false</static>
<min_dist>0</min_dist>
<max_dist>8</max_dist>
</track_visual>
</camera>
</gui>

<model name="box">
<pose>0 0 0.5 0 0 0</pose>
<link name="link">
<kinematic>true</kinematic>
<collision name="collision">
<geometry>
<box>
<size>1 1 1</size>
</box>
</geometry>
<surface>
<friction>
<ode>
<mu>0.0</mu>
<mu2>0.0</mu2>
</ode>
</friction>
</surface>
</collision>
<visual name="visual">
<geometry>
<box>
<size>1 1 1</size>
</box>
</geometry>
</visual>
</link>

<!-- Apply a random velocity to the specified link-->
<!-- In this example, we move a box around. A key property of the link
is the frictionless surface -->
<plugin name="random" filename="libRandomVelocityPlugin.so">

<!-- Name of the link in this model that receives the velocity -->
<link>link</link>

<!-- Initial velocity that is applied to the link -->
<initial_velocity>0 0.5 0</initial_velocity>

<!-- Scaling factor that is used to compute a new velocity -->
<velocity_factor>0.5</velocity_factor>

<!-- Time, in seconds, between new velocities -->
<update_period>5</update_period>

<!-- Clamp the Z velocity value to zero. You can also clamp x and
y values -->
<min_z>0</min_z>
<max_z>0</max_z>
</plugin>
</model>

<model name="sphere">
<pose>4 2 0.5 0 0 0</pose>
<link name="link">
<collision name="collision">
<geometry>
<sphere>
<radius>0.5</radius>
</sphere>
</geometry>
</collision>
<visual name="visual">
<geometry>
<sphere>
<radius>0.5</radius>
</sphere>
</geometry>
</visual>
</link>

<plugin name="initial" filename="libInitialVelocityPlugin.so">
<linear>0 0 0</linear>
<angular>0 0 1</angular>
</plugin>
</model>
</world>
</sdf>
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136 changes: 136 additions & 0 deletions track_visual/tutorial.md
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# Overview

This tutorial demonstrates how you can track a visual with the user camera by
using the SDF `<track_visual>` tag or the GUI.

## Quick start

1. Let's start by creating a directory for this tutorial:

~~~
mkdir ~/tutorial_track_visual
cd ~/tutorial_track_visual
~~~

2. Download this file:
[`track_visual.world`](http://bitbucket.org/osrf/gazebo_tutorials/raw/default/track_visual/files/track_visual.world)
into the current directory. You can use this command:

~~~
wget http://bitbucket.org/osrf/gazebo_tutorials/raw/default/track_visual/files/track_visual.world
~~~

You should get this world file:

<include src='http://bitbucket.org/osrf/gazebo_tutorials/raw/default/track_visual/files/track_visual.world' />

3. Start gazebo:

~~~
gazebo track_visual.world
~~~

You should see a cube moving randomly around the world's origin.

## The world explained

Let's go further and understand the different elements of the `track_visual.world`.

<include from='/ <gui/' to='/</name>/' src='http://bitbucket.org/osrf/gazebo_tutorials/raw/default/track_visual/files/track_visual.world' />

Within the `track_visual` tag, you can see how to select a visual by specifying a `<name>` tag. The visual will be tracked from startup. The camera will follow the model by changing its orientation.

<include from='/ <static/' to='/</max_dist>/' src='http://bitbucket.org/osrf/gazebo_tutorials/raw/default/track_visual/files/track_visual.world' />

Because `<static>` is set to `false`, the position of the camera may vary but the distance between the camera and the model origin will depend on the value of the `min_dist` and `max_dist` elements.

Now change `<static>` to `true`:

<gui>
<camera name="user_camera">
<track_visual>
<name>box</name>
<static>true</static>
</track_visual>
</camera>
</gui>

Relaunch Gazebo. The position of the camera is now fixed relatively to the model being tracked.

By default, the camera is located 5 meters behind and 1 meter above the model. Try changing its location by specifying a `<xyz>` tag:

<gui>
<camera name="user_camera">
<track_visual>
<name>box</name>
<static>true</static>
<xyz>3 2 5</xyz>
</track_visual>
</camera>
</gui>

Relaunch Gazebo. The camera is now located 3 meters in front, 2 meters to the left, and 5 meters above the tracked model.

Finally, we introduce the `<use_model_frame>` tag whose default value is `true`. When the `<static>` tag is `true`, this element specifies whether the coordinates provided by `<xyz>` are relative to the model reference frame or the world reference frame. Try changing the value of the `<use_model_frame>` tag:

<gui>
<camera name="user_camera">
<track_visual>
<name>box</name>
<static>true</static>
<use_model_frame>false</use_model_frame>
<xyz>0 0 10</xyz>
</track_visual>
</camera>
</gui>

Relaunch Gazebo. The camera is now staying 10 meters above the origin.

To illustrate the last element `<inherit_yaw>`, we will track a sphere instead of a cube. Change `<name>` to `sphere` and make sure that `<static>` and `<use_model_frame>` are set to `true`:

<gui>
<camera name="user_camera">
<track_visual>
<name>sphere</name>
<static>true</static>
<use_model_frame>true</use_model_frame>
<xyz>-3 0 0</xyz>
</track_visual>
</camera>
</gui>

Relaunch Gazebo. You should now see a sphere rotating in front of the camera. By default, the camera is configured to ignore the pitch, roll and yaw of the model. To inherit the yaw rotation of the visual, simply set the `<inherit_yaw>` tag to `true`:

<gui>
<camera name="user_camera">
<track_visual>
<name>sphere</name>
<static>true</static>
<use_model_frame>true</use_model_frame>
<xyz>-3 0 0</xyz>
<inherit_yaw>true</inherit_yaw>
</track_visual>
</camera>
</gui>

Relaunch Gazebo. The camera should now rotate around the sphere as it turns around.

Below is the complete list of elements that can be set within `<track_visual>`:

* `<name>`: Name of the tracked visual. If no name is provided, the remaining settings will be applied whenever tracking is triggered in the GUI. This parameter is never ignored.
* `<static>`: If set to `true`, the position of the camera is fixed relatively to the model or to the world, depending on the value of the `<use_model_frame>` element. Otherwise, the position of the camera may vary but the distance between the camera and the model will depend on the value of the `<min_dist>` and `<max_dist>` elements. In any case, the camera will always follow the model by changing its orientation. This parameter is never ignored.
* `<min_dist>`: Minimum distance between the camera and the tracked visual. This parameter is ignored when `<static>` is `true`.
* `<max_dist>`: Maximum distance between the camera and the tracked visual. This parameter is ignored when `<static>` is `true`.
* `<use_model_frame>`: If set to `true`, the position of the camera is relative to the model reference frame, which means that its position relative to the model will not change. Otherwise, the position of the camera is relative to the world reference frame, which means that its position relative to the world will not change. This parameter is ignored when `<static>` is `false`.
* `<xyz>`: The position of the camera's reference frame. If `<use_model_frame>` is set to `true`, the position is relative to the model reference frame, otherwise it represents world coordinates. This parameter is ignored when `<static>` is `false`.
* `<inherit_yaw>`: If set to `true`, the camera will inherit the yaw rotation of the tracked model. This parameter is ignored when `<static>` is `false` or when `<use_model_frame>` is `false`. In other words, it is only used if `<static>` and `<use_model_frame>` are both `true`.

## Dynamic Reconfigure

The camera properties can be adjusted dynamically within Gazebo.

In the `World` tab, select the `GUI` item. A list of GUI properties will be displayed in the list box below. Click the triangle to expand the properties if needed.

[[file:files/tutorialGUIExpanded.png|257px]]

These properties allow you to dynamically change the parameters defined in `<track_visual>`. They will be applied whenever a model is being followed by the camera.