Explanation of exported TR3 mesh structure node/points connections in a .dat file

could someone please explain to me the way catia arranged the OctreeTriangle Mesh (TR3) mesh structure node/points connections in a .dat file. Because when i imported the same coordinates of the points into catia, and it formed the structure nicely. But when I tried connecting the points like how it is written in the .dat file, the connections do not make sense. The coordinates of each point are usually written on the top part of the file, and the connections on the last part (below the coordinates).

Please if you are still confused, you can create a structure, mesh it with OctreeTriangule Mesh and export it to a dat file.

The file format is known as a standard NASTRAN bulk data format. 

Each record is 80 characters (punch card friendly... this is an old file format).

Each GRID record gives an index number and a coordinate.

Each CTRIA3 record describes a triangle by listing the 3 GRID indicies it is connected to.  

No you cannot recreate the surface by drawing a polyline or spline through the grid points. They have no implicit order.

How to ask questions 

From what you have said, am i to understand that if one was to trace back the points of one triangle in the dat file to that in the Catia structure, it is different?! if so is there a way to find a relationship between its arrangement in the dat file and the points in the cat mesh structure.

The points will be on the model. They will correspond to triangle corners on your mesh.

However, CATIA hides the node numbers from the user when you edit a mesh in CATIA you really don't have any notion of which point is which. 

If you make one polyline per triangle, then fill it, you can reproduce, very inefficiently,  your mesh as a poor quality surface.

If you want to use the mesh as input the building geometry seriously the Digitized Shape Editor and Quick Surface Reconstruction workbenches can work with the mesh data. 

How to ask questions 

Okay i get it. I fully understand now, Thank you for your help