Thanks! Here are my vtk file format
vtk DataFile Version 3.0
Structured Points
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 64 64 64
ORIGIN 1 1 1
SPACING 1 1 1
POINT_DATA 262144
SCALARS scalars float
LOOKUP_TABLE domain
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
24.0
…