Method of generating volume hologram using point cloud and mesh

A method of generating a volume hologram using a point cloud and a mesh, the method comprising:

• (a) acquiring multi-view depth and color images;
• (b) generating point cloud data of a three-dimensional object from the acquired multi-view depth and color images;
• (c) generating mesh data of the three-dimensional object from the point cloud data of the three-dimensional object;
• (d) calculating a normal vector of each mesh from the mesh data of the three-dimensional object;
• (e) extracting three-dimensional data at a user viewpoint from the mesh data of the three-dimensional object by using the normal vector of the mesh;
• and
• (f) generating hologram data from the three-dimensional data at the user viewpoint,
• wherein, in the step (e), a direction vector at the user viewpoint is acquired, an inner product of the direction vector at the user viewpoint and the normal vector of the mesh is calculated to extract only a mesh where a result value of the inner product is a non-negative number, and the extracted mesh serves as the three-dimensional data at the user viewpoint, and
• wherein the direction vector at the user viewpoint is acquired by setting a Z-axis direction as a basic direction vector, and rotating the basic direction vector by using a yaw, a pitch, and a roll at a rotated user viewpoint.

A method of generating a volume hologram using a point cloud and a mesh, the method comprising:

• (a) acquiring multi-view depth and color images;
• (b) generating point cloud data of a three-dimensional object from the acquired multi-view depth and color images;
• (c) generating mesh data of the three-dimensional object from the point cloud data of the three-dimensional object;
• (d) calculating a normal vector of each mesh from the mesh data of the three-dimensional object;
• (e) extracting three-dimensional data at a user viewpoint from the mesh data of the three-dimensional object by using the normal vector of the mesh;
• and
• (f) generating hologram data from the three-dimensional data at the user viewpoint,
• wherein, in the step (e), a direction vector at the user viewpoint is acquired, an inner product of the direction vector at the user viewpoint and the normal vector of the mesh is calculated to extract only a mesh where a result value of the inner product is a non-negative number, and the extracted mesh serves as the three-dimensional data at the user viewpoint,
• wherein, in the step (f), with respect to the extracted three-dimensional data at the user viewpoint, a density of the three-dimensional data is adjusted, and the hologram data is generated from the three-dimensional data at the user viewpoint in which the density is adjusted,
• wherein, with respect to mesh data corresponding to the extracted three-dimensional data at the user viewpoint, a size of each mesh is measured to determine whether the measured mesh size is less than a threshold value, the mesh is divided by adding a point to the mesh when the measured mesh size is greater than the threshold value, and the division process is repeatedly performed such that all meshes are divided to have a size less than the threshold value, thereby adjusting the density, and
• wherein, with respect to a mesh having a size greater than or equal to the threshold value, a location of the point to be generated is calculated by using a circumcenter of a triangle, color information of the generated point has an average value of each point, and a normal vector is set as a normal vector of the mesh, thereby adding the point.