OpenCV模块熟悉：点云处理相关

1. 显示--VIZ

曾经基于PCL 做过不少点云相关的开发，采样VTK进行有点云显示。后来基于OpenCV做了不少三维重建工作，总是将点云保存下来，然后借助CloudCompare等查看结果。如果能够将VIZ编译进来，预计会提升开发速度。
在Ubuntu下，VIZ的安装较为简单（珍爱生命，学习就用不要用Windows了）。在编译好OpenCV + Contrib之后（网上很多教程，这里不再赘述）。在build的目录内打开终端，输入下列命令行即可。

//安装VTK

sudo apt-get install libvtk6-dev

//打开vtk，生成及安装

cmake -DWITH_VTK=ON ..

make

sudo make install

//加载配置

ldconfig

测试VIZ,输入如下代码，测试、运行。

#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;
 
 rot_vec.at<float>(0, 0) += (float)CV_PI * 0.01f;
 rot_vec.at<float>(0, 1) += (float)CV_PI * 0.01f;
 rot_vec.at<float>(0, 2) += (float)CV_PI * 0.01f;
 
 translation_phase += (float)CV_PI * 0.01f;
 translation = sin(translation_phase);
 
 Mat rot_mat;
 Rodrigues(rot_vec, rot_mat);
 cout << "rot_mat = " << rot_mat << endl;
 Affine3f pose(rot_mat, Vec3f(translation, translation, translation));
 Affine3f pose2(pose.matrix);
 cout << "pose = " << pose.matrix << endl;
 cout << "pose = " << pose2.matrix << endl;
 
 
 
 while(!myWindow.wasStopped())
 {
 /* Rotation using rodrigues */
 rot_vec.at<float>(0,0) += (float)CV_PI * 0.01f;
 rot_vec.at<float>(0,1) += (float)CV_PI * 0.01f;
 rot_vec.at<float>(0,2) += (float)CV_PI * 0.01f;
 
 translation_phase += (float)CV_PI * 0.01f;
 translation = sin(translation_phase);
 
 Mat rot_mat1;
 Rodrigues(rot_vec, rot_mat1);
 
 Affine3f pose1(rot_mat1, Vec3f(translation, translation, translation));
 
 myWindow.setWidgetPose("Cube Widget", pose1);
 
 myWindow.spinOnce(1, true);
 }
 
 return 0;
}

运行上述代码之后，一个运动的正方体框会被展示出来。