Spherical coordinates with vtk file

I have a vtk file which contains coordinate data(latitude and longitude values) as field arrays. I want it to be rendered as a sphere(an earth surface), the problem is that my vtk file contains 136 elements in latitude while 268 in longitude, and as a result 136x268 points in total. However, they’re not regularly arranged, instead they are stored exactly for each point.
i.e. the Xth point’s position is equal to the Xth element of latitude array and longitude array, all of which contains 136x268 elements.
It seems that vtk file is not capable of handling this, what should I do?

Thanks for any help.