I have an array of vertices from the .obj file. I transferred it to a blender . BUT I can't create the surface.
how to combine points into a single surface ??
This is not any old point-cloud.. working on the assumption the points are on a rectangular grid of rectangles, in the XY of its own object space, with Z as height, here's a GN modifier to derive a quad surface from it:
Just bureaucracy really, nothing exciting, getting counts and positions from the point-grid, as shown: (The mystery 'SZ0' node is Geometry > Transform> scale Z to 0.)
A vertex is just a single point in Blender. It won't be rendered.
An edge is just connection between two points in vertex. It won't be rendered.
A face is the connection of multiple edges, it will be rendered.
Additional infos: https://docs.blender.org/manual/en/2.79/modeling/meshes/structure.html
So i think you need more information than just "points". You need edges information (which points should be connected) and you need face information (which edges are used to build a face).
But yes, if your "points" are just heights of course you could convert them into a surface, but you didn't write that explicitely.
Made a quick video tutorial related to @Edgel3D comment: (Use shrinkwrap modifier) Verteces to Surface