creating terrain

Greetings. I have one difficulty.
I need to create type of a landscape (or a map of heights - to whom as to like). At me from a file of data coordinates of points are loaded.
I know, that for this problem it is possible to use gluNurbsSurface or glMap2f (glEvalMesh2) objects. All like good and a landscape normal
it is created - a smooth surface and so on. But there is one problem, killing all my achievements. There are restrictions on number of data points. For glMap2f it is 30 (glGetIntegerv (GL_MAX_EVAL_ORDER,
nstep)), and for gluNurbsSurface the order 20. That is I am real can to build a surface, if number of initial points of data of the order 3030 for the first case and 20*20 for the second. There are assumptions, I hope that
it is not right, that this restriction by these means to bypass is impossible. But I
i do not wish to build pieces, to divide initial data into squares - checked, but there are other problems with quality and speed of a conclusion.
May be it is possible this restriction to overcome. If is not present, similar it is necessary to build meshes by hands. Then prompt as them correctly to build.
P.S. I don’t need use any other programs like photoshop or 3dmax for creating terrain. It is important!!!

you probably don’t need higher order than 2 for gluNurbsSurface. Overlap control points to keep good derivation continuity, and you are free to go for much larger terrains.
Or don’t smooth the terrain, and just draw quad strips, it is much simpler and depending on the terrain resolution it can be fine enough.