I would like to know what the the method that ParaView uses to interpolate valued from element to nodes in the Filter CellDatatoPointData.
Is there any documentation about the algorithm used in this filter?
I was not able to find any documentation about it.



map cell data to point data

vtkCellDataToPointData is a filter that transforms cell data (i.e., data specified per cell) into point data (i.e., data specified at cell points). The method of transformation is based on averaging the data values of all cells using a particular point. For large datasets with several cell data arrays, the filter optionally supports selective processing to speed up processing. Optionally, the input cell data can be passed through to the output as well. Unstructured grids and polydata can have cells of different dimensions. To handle different use cases in this situation, the user can specify which cells contribute to the computation. The options for this are All (default), Patch and DataSetMax. Patch uses only the highest dimension cells attached to a point. DataSetMax uses the highest cell dimension in the entire data set.

From the code it looks like all cells around a particular point are weighted similarly in the interpolation for that point.
This may be an issue if cell sizes around a point vary highly, which may be the case for unstructured grids.