vendor: OpenCV 5.0.0 snapshot at 755e50675d97db9b7d449d8bd6b09888646f6c6e

2026-08-22 00:11:13 +08:00
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+Training data generation using Icosphere {#tutorial_data_generation}
+=============
+
+Goal
+----
+
+In this tutorial you will learn how to
+
+-   Conduct a point cloud of camera view on sphere.
+-   Generate training images using 3D model.
+
+Code
+----
+
+@include cnn_3dobj/samples/sphereview_data.cpp
+
+Explanation
+-----------
+
+Here is the general structure of the program:
+
+-   Create a window.
+    @code{.cpp}
+    viz::Viz3d myWindow("Coordinate Frame");
+    @endcode
+
+-   Set window size as 64*64, we use this scale as default.
+    @code{.cpp}
+    myWindow.setWindowSize(Size(64,64));
+    @endcode
+
+-   Add coordinate axes.
+    @code{.cpp}
+    myWindow.showWidget("Coordinate Widget", viz::WCoordinateSystem());
+    myWindow.setBackgroundColor(viz::Color::gray());
+    myWindow.spin();
+    @endcode
+
+-   Create a Mesh widget, loading .ply models.
+    @code{.cpp}
+    viz::Mesh objmesh = viz::Mesh::load(plymodel);
+    @endcode
+-   Get the center of the generated mesh widget, cause some .ply files.
+    @code{.cpp}
+    Point3d cam_focal_point = ViewSphere.getCenter(objmesh.cloud);
+    @endcode
+
+-   Get the pose of the camera using makeCameraPoses.
+    @code{.cpp}
+    Affine3f cam_pose = viz::makeCameraPose(campos.at(pose)*radius+cam_focal_point, cam_focal_point, cam_y_dir*radius+cam_focal_point);
+    @endcode
+
+-   Get the transformation matrix from camera coordinate system to global.
+    @code{.cpp}
+    Affine3f transform = viz::makeTransformToGlobal(Vec3f(1.0f,0.0f,0.0f), Vec3f(0.0f,1.0f,0.0f), Vec3f(0.0f,0.0f,1.0f), campos.at(pose));
+    viz::WMesh mesh_widget(objmesh);
+    @endcode
+
+-   Save screen shot as images.
+    @code{.cpp}
+    myWindow.saveScreenshot(filename);
+    @endcode
+
+-   Write images into binary files for further using in CNN training.
+    @code{.cpp}
+    ViewSphere.writeBinaryfile(filename, binaryPath, headerPath,(int)campos.size()*num_class, label_class, (int)(campos.at(pose).x*100), (int)(campos.at(pose).y*100), (int)(campos.at(pose).z*100), rgb_use);
+    @endcode
+
+Results
+-------
+
+Here is collection images created by this demo using 4 model.
+
+![](images_all/1_8.png)