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      1 /**
      2  * @file transformations.cpp
      3  * @brief Visualizing cloud in different positions, coordinate frames, camera frustums
      4  * @author Ozan Cagri Tonkal
      5  */
      6 
      7 #include <opencv2/viz.hpp>
      8 #include <iostream>
      9 #include <fstream>
     10 
     11 using namespace cv;
     12 using namespace std;
     13 
     14 /**
     15  * @function help
     16  * @brief Display instructions to use this tutorial program
     17  */
     18 void help()
     19 {
     20     cout
     21     << "--------------------------------------------------------------------------"   << endl
     22     << "This program shows how to use makeTransformToGlobal() to compute required pose,"
     23     << "how to use makeCameraPose and Viz3d::setViewerPose. You can observe the scene "
     24     << "from camera point of view (C) or global point of view (G)"                    << endl
     25     << "Usage:"                                                                       << endl
     26     << "./transformations [ G | C ]"                                                 << endl
     27     << endl;
     28 }
     29 
     30 /**
     31  * @function cvcloud_load
     32  * @brief load bunny.ply
     33  */
     34 Mat cvcloud_load()
     35 {
     36     Mat cloud(1, 1889, CV_32FC3);
     37     ifstream ifs("bunny.ply");
     38 
     39     string str;
     40     for(size_t i = 0; i < 12; ++i)
     41         getline(ifs, str);
     42 
     43     Point3f* data = cloud.ptr<cv::Point3f>();
     44     float dummy1, dummy2;
     45     for(size_t i = 0; i < 1889; ++i)
     46         ifs >> data[i].x >> data[i].y >> data[i].z >> dummy1 >> dummy2;
     47 
     48     cloud *= 5.0f;
     49     return cloud;
     50 }
     51 
     52 /**
     53  * @function main
     54  */
     55 int main(int argn, char **argv)
     56 {
     57     help();
     58 
     59     if (argn < 2)
     60     {
     61         cout << "Missing arguments." << endl;
     62         return 1;
     63     }
     64 
     65     bool camera_pov = (argv[1][0] == 'C');
     66 
     67     /// Create a window
     68     viz::Viz3d myWindow("Coordinate Frame");
     69 
     70     /// Add coordinate axes
     71     myWindow.showWidget("Coordinate Widget", viz::WCoordinateSystem());
     72 
     73     /// Let's assume camera has the following properties
     74     Point3f cam_pos(3.0f,3.0f,3.0f), cam_focal_point(3.0f,3.0f,2.0f), cam_y_dir(-1.0f,0.0f,0.0f);
     75 
     76     /// We can get the pose of the cam using makeCameraPose
     77     Affine3f cam_pose = viz::makeCameraPose(cam_pos, cam_focal_point, cam_y_dir);
     78 
     79     /// We can get the transformation matrix from camera coordinate system to global using
     80     /// - makeTransformToGlobal. We need the axes of the camera
     81     Affine3f transform = viz::makeTransformToGlobal(Vec3f(0.0f,-1.0f,0.0f), Vec3f(-1.0f,0.0f,0.0f), Vec3f(0.0f,0.0f,-1.0f), cam_pos);
     82 
     83     /// Create a cloud widget.
     84     Mat bunny_cloud = cvcloud_load();
     85     viz::WCloud cloud_widget(bunny_cloud, viz::Color::green());
     86 
     87     /// Pose of the widget in camera frame
     88     Affine3f cloud_pose = Affine3f().translate(Vec3f(0.0f,0.0f,3.0f));
     89     /// Pose of the widget in global frame
     90     Affine3f cloud_pose_global = transform * cloud_pose;
     91 
     92     /// Visualize camera frame
     93     if (!camera_pov)
     94     {
     95         viz::WCameraPosition cpw(0.5); // Coordinate axes
     96         viz::WCameraPosition cpw_frustum(Vec2f(0.889484, 0.523599)); // Camera frustum
     97         myWindow.showWidget("CPW", cpw, cam_pose);
     98         myWindow.showWidget("CPW_FRUSTUM", cpw_frustum, cam_pose);
     99     }
    100 
    101     /// Visualize widget
    102     myWindow.showWidget("bunny", cloud_widget, cloud_pose_global);
    103 
    104     /// Set the viewer pose to that of camera
    105     if (camera_pov)
    106         myWindow.setViewerPose(cam_pose);
    107 
    108     /// Start event loop.
    109     myWindow.spin();
    110 
    111     return 0;
    112 }
    113