学习目标

这次学习中将学会下面三部分：

• 添加一些部件到可视化窗口
• 使用Affine3设置部件的姿势
• 部件沿轴旋转与平移

代码

#include <opencv2/viz.hpp>
#include <opencv2/calib3d.hpp>
#include <iostream>
using namespace cv;
using namespace std;
static void help()
{
    cout
    << "--------------------------------------------------------------------------"   << endl
    << "This program shows how to visualize a cube rotated around (1,1,1) and shifted "
    << "using Rodrigues vector."                                                      << endl
    << "Usage:"                                                                       << endl
    << "./widget_pose"                                                                << endl
    << endl;
}
int main()
{
    help();
    viz::Viz3d myWindow("Coordinate Frame");
    myWindow.showWidget("Coordinate Widget", viz::WCoordinateSystem());
    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);
    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);
    Mat rot_vec = Mat::zeros(1,3,CV_32F);
    float translation_phase = 0.0, translation = 0.0;
    while(!myWindow.wasStopped())
    {
        /* Rotation using rodrigues */
        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;
        translation_phase += CV_PI * 0.01f;
        translation = sin(translation_phase);
        Mat rot_mat;
        Rodrigues(rot_vec, rot_mat);
        Affine3f pose(rot_mat, Vec3f(translation, translation, translation));
        myWindow.setWidgetPose("Cube Widget", pose);
        myWindow.spinOnce(1, true);
    }
    return 0;
}

解释

• 创建一个可视化窗口

viz::Viz3d myWindow("Coordinate Frame");

• 使用CoordinateSystemWidget在窗口中显示坐标轴

myWindow.showWidget("Coordinate Widget", viz::WCoordinateSystem());

• 展示一条线，这条线代表轴(1,1,1)

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);

• 构建一个立方体

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);

• 创建一个旋转矩阵

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);

• 使用Affine3f设置立方体的姿势

Affine3f pose(rot_mat, Vec3f(translation, translation, translation));
myWindow.setWidgetPose("Cube Widget", pose);

• 使用wasStopped和spinOnce对旋转进行动画处理

while(!myWindow.wasStopped())
{
    ...
    myWindow.spinOnce(1, true);
}

结果