Use Third-Party Normal Vectors

NUBIGON can calculate normal vectors for your point clouds while opening them. But if your ASCII file (XYZ, PTS, TXT) already contains normal vectors, NUBIGON can read this information as well. 

When opening point clouds with normal vectors, first specify the channels containing the normal information in the ASCII file dialogue.

Then uncheck Compute normals in the Octree Generation Settings dialogue to avoid an override.