Open Source Computer Vision Library https://opencv.org/
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Pose of a widget {#tutorial_widget_pose}
================
@prev_tutorial{tutorial_launching_viz}
@next_tutorial{tutorial_transformations}
Goal
----
In this tutorial you will learn how to
- Add widgets to the visualization window
- Use Affine3 to set pose of a widget
- Rotating and translating a widget along an axis
Code
----
You can download the code from [here ](https://github.com/opencv/opencv/tree/3.4/samples/cpp/tutorial_code/viz/widget_pose.cpp).
@include samples/cpp/tutorial_code/viz/widget_pose.cpp
Explanation
-----------
Here is the general structure of the program:
- Create a visualization window.
@code{.cpp}
/// Create a window
viz::Viz3d myWindow("Coordinate Frame");
@endcode
- Show coordinate axes in the window using CoordinateSystemWidget.
@code{.cpp}
/// Add coordinate axes
myWindow.showWidget("Coordinate Widget", viz::WCoordinateSystem());
@endcode
- Display a line representing the axis (1,1,1).
@code{.cpp}
/// Add line to represent (1,1,1) axis
viz::WLine axis(Point3f(-1.0f,-1.0f,-1.0f), Point3f(1.0f,1.0f,1.0f));
axis.setRenderingProperty(viz::LINE_WIDTH, 4.0);
myWindow.showWidget("Line Widget", axis);
@endcode
- Construct a cube.
@code{.cpp}
/// Construct a cube widget
viz::WCube cube_widget(Point3f(0.5,0.5,0.0), Point3f(0.0,0.0,-0.5), true, viz::Color::blue());
cube_widget.setRenderingProperty(viz::LINE_WIDTH, 4.0);
myWindow.showWidget("Cube Widget", cube_widget);
@endcode
- Create rotation matrix from rodrigues vector
@code{.cpp}
/// Rotate around (1,1,1)
rot_vec.at<float>(0,0) += CV_PI * 0.01f;
rot_vec.at<float>(0,1) += CV_PI * 0.01f;
rot_vec.at<float>(0,2) += CV_PI * 0.01f;
...
Mat rot_mat;
Rodrigues(rot_vec, rot_mat);
@endcode
- Use Affine3f to set pose of the cube.
@code{.cpp}
/// Construct pose
Affine3f pose(rot_mat, Vec3f(translation, translation, translation));
myWindow.setWidgetPose("Cube Widget", pose);
@endcode
- Animate the rotation using wasStopped and spinOnce
@code{.cpp}
while(!myWindow.wasStopped())
{
...
myWindow.spinOnce(1, true);
}
@endcode
Results
-------
Here is the result of the program.
\htmlonly
<div align="center">
<iframe width="420" height="315" src="https://www.youtube.com/embed/22HKMN657U0" frameborder="0" allowfullscreen></iframe>
</div>
\endhtmlonly