Ah! Two issues:
- calculator filter is producing 3-component arrays alone, even when 2 component was requested.
- 3-component tcoords don’t correctly map 2D texture images.
Solution is to use Python Progammable filter instead. I applied a Python Programmable filter with the following script after your Calculator filter and then things worked as expected.
output.PointData.append(inputs[0].PointData["Result"][:,0:1], "Result2")
output.PointData.SetActiveTCoords("Result2")
You can totally ditch the Calculator and just update the expression in the Programmable Filter instead, as well.