On the other hand, if all we have is point cloud data without connectivity information, then in order to resolve such ambiguities, we need to make additional assumptions. Would mean that points with indices 15, 17, and 23 are connected as the vertices in a triangle. For example, in a surface triangle data file, a row such as 15 17 23 We then have a list of triangles defined by the connectivity between points, which uniquely defines the surface. If an imported list of 3D coordinates comes with associated triangulated surface connectivity data, such as for the STL, PLY, or 3MF file formats, then this ambiguity is resolved. Are points 5, 6, and 4 connected? In this case they are not connected, which can be seen from the original curve, but not from its relatively sparsely sampled point cloud. Point cloud data may have intrinsic ambiguities. Perhaps 5, 6, and 4 are consecutive points on the curve? However, in the next figure, which corresponds to the curve represented by imported point cloud data, this is not so obvious. From the figure, it is obvious that the points 5, 18, and 7 are consecutive points on the curve. Consider the 2D curve in the figure below. To illustrate the type of ambiguity that may occur, let’s look at a simple 2D example. There are often ambiguities in such a point set, since there is no information about the relationship between the points, also known as connectivity. Once imported, a point is assigned an index according to the line number in the file for its coordinates. Values and indices can be separated by space, comma, semicolon, or tab characters. In this format, you can use an optional % (percent) character to indicate a comment line. In the software, it is called the Spreadsheet format. This is one of the simplest types of coordinate formats that COMSOL Multiphysics can import. The screenshot below of a text file in Notepad shows the beginning of a point cloud data file with x-, y-, and z-coordinates organized in tab-separated columns. The points typically originate from the surface of a physical object that has been scanned using a laser, metrology tools, radar, etc.

In this blog post, we will show how point cloud data can be converted to geometry models that can be used for simulation in the COMSOL Multiphysics® software.Ī point cloud is a set of points in 3D given by x-, y-, and z-coordinates. Sometimes the only data you have available is a set of points, also known as a point cloud. Not all analysis projects start with a CAD model.

Convert mesh to geometry meshlab