Space filling Curve start point

Question

I am working with Hilbert curve and Z order curve in python. I am trying to use these curves to find a 'sorting' for CIELAB points. In order to compare them, I would like to set the start point to be on the same point. As far as I'm aware, the onyl way to ensure that they both start on the same point is by forcing this point onto the origin. However, this can't be done as the z-order and hilbert curve implementation require positive integer values. I am using the following implementations in python:

• hilbert : https://github.com/galtay/hilbertcurve/blob/main/hilbertcurve/hilbertcurve.py
• Z order : https://github.com/rmrschub/zCurve/blob/main/zCurve/zCurve.py

I would appreciate any suggestions on how to force a point onto the origin while maintaining spatial locality of the points and ensuring all points stay positive. Alternatively, I am open to other suggestions on how to maintain the same start point across both curves. Thanks in advance

I have tried scaling and rotating data with no luck