opencv/doc/tutorials/3d/point_cloud/point_cloud.markdown
Rostislav Vasilikhin f96111ef05
Merge pull request #24961 from savuor:rv/ply_mesh
PLY mesh support #24961

**Warning:** The PR changes exising API.

Fixes #24960
Connected PR: [#1145@extra](https://github.com/opencv/opencv_extra/pull/1145)

### Changes
* Adds faces loading from and saving to PLY files
* Fixes incorrect PLY loading (see issue)
* Adds per-vertex color loading / saving

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake
2024-02-12 15:34:54 +03:00

2.3 KiB

Point cloud visualisation

Original author Dmitrii Klepikov
Compatibility OpenCV >= 5.0

Goal

In this tutorial you will:

  • Load and save point cloud data
  • Visualise your data

Requirements

For visualisations you need to compile OpenCV library with OpenGL support. For this you should set WITH_OPENGL flag ON in CMake while building OpenCV from source.

Practice

Loading and saving of point cloud can be done using cv::loadPointCloud and cv::savePointCloud accordingly.

Currently supported formats are:

  • .OBJ (supported keys are v(which is responsible for point position), vn(normal coordinates) and f(faces of a mesh), other keys are ignored)
  • .PLY (all encoding types(ascii and byte) are supported with limitation to only float type for data)

@code{.py} vertices, normals = cv2.loadPointCloud("teapot.obj") @endcode

Function cv::loadPointCloud returns vector of points of float (cv::Point3f) and vector of their normals(if specified in source file). To visualize it you can use functions from viz3d module and it is needed to reinterpret data into another format

@code{.py} vertices = np.squeeze(vertices, axis=1)

color = [1.0, 1.0, 0.0] colors = np.tile(color, (vertices.shape[0], 1)) obj_pts = np.concatenate((vertices, colors), axis=1).astype(np.float32)

cv2.viz3d.showPoints("Window", "Points", obj_pts)

cv2.waitKey(0) @endcode

In presented code sample we add a colour attribute to every point Result will be:

For additional info grid can be added

@code{.py} vertices, normals = cv2.loadPointCloud("teapot.obj") @endcode

Other possible way to draw 3d objects can be a mesh. For that we use special functions to load mesh data and display it. Here for now only .OBJ files are supported and they should be triangulated before processing (triangulation - process of breaking faces into triangles).

@code{.py} vertices, indices = cv2.loadMesh("../data/teapot.obj") vertices = np.squeeze(vertices, axis=1)

cv2.viz3d.showMesh("window", "mesh", vertices, indices) @endcode