So currently the way the texture map is stored is vertical, and when a voxel is taller than it is wide, the tall part gets clipped to the size of the width, resulting in any pixels above becoming white.

I'm proposing the texture map be saved with the top/bottom/sides facing sideways, and then the front/back being at the bottom, as per diagram. Since the 99.99999% of voxels are longer than they are wide (and longer than tall)... and we all use wide screen monitors right?

This would make the resulting bmp canvas more square and easier to work with in a photo editor, while simultaneously removing the height constraint currently imposed by the width determining the canvas.

PS. the front/rear view should be flipped right-side-up but I forgot