creating a closed model in Meshlab without normals

Question

I am trying to create a printable 3D model of amplitude data. I have used R to extract the amplitudes of sound across a surface and assigned them X and Y coordinates. I am trying to use MeshLab to turn these points into a solid printable object. I imported the points as a text file but the problem comes with assigning normals. Because there is no normals data attached, and the program does not know which way is out it assigns normals that then generate incorrect meshes. I have tried reorienting all the normals but this also does not have an affect. The point cloud is 2 million points and even when I reduce its size to less than 1 million it does not fix the problem. Is there a way for all the normals to face outward? Any advice would be appreciated. I'm very new to MeshLab so simple explanations are possible!