Code to transform a subdivided cube mesh into a sphere using WPFs 3D classes.

planetGen_sphere.cs

// Load base mesh
_currentModel = ModelImporter.Load(_localPath + @"Models\planetCube.3ds");

Model3DGroup modelGroup = (Model3DGroup)_currentModel;

GeometryModel3D model = (GeometryModel3D)modelGroup.Children[0]; // The first child of model group is the imported mesh.
model.BackMaterial = null;

// Make spherical
MeshGeometry3D mesh = (MeshGeometry3D)model.Geometry; // Grab reference to raw mesh data.

mesh.Normals = new Vector3DCollection(mesh.Positions.Count); // Create a new collection of normals.

for (int i = 0; i < mesh.Positions.Count; i++)
{
    // Grab vectory and normilize.
    Vector3D v = mesh.Positions[i].ToVector3D();
    v.Normalize();

    // Add nomilized vector as normal.
    mesh.Normals.Add(v); 
    
    // Project normilized vector outword.
    v *= 2.0; 
    
    mesh.Positions[i] = new Point3D(v.X, v.Y, v.Z); // Overwrite original.
}