[Paraview] Question about Integrate Variables Filter

[Magician]

Hi all,


I'm now comparing integration results of each postprocessors.
I made a simple Quadratic VTK model as below:
> # vtk DataFile Version 2.0

> QuadCell
> ASCII
> DATASET UNSTRUCTURED_GRID
> POINTS 4 FLOAT
> 0 0 0
> 1 0 0
> 0 1 0
> 1 1 0
> CELLS 1 5
> 4 0 1 3 2
> CELL_TYPES 1
> 9
> POINT_DATA 4
> SCALARS scalar FLOAT 1
> LOOKUP_TABLE DEFAULT
> 0.0
> 1.0
> 2.0
> 4.0

When I apply Point Data to Cell Data filter,
scalar values are interpolated as 1.75.
It may be calculated as (0.0+1.0+2.0+4.0)/4.0.

But when I apply Integrate Variables filter,
scalar value is integrated as 1.833....
The area value of quadratic cell is 1.0, so I thought
integrated values should be equal to cell data.

How the integrated value is calculated?


Magician