# Threshold on slice using an ellipse

Hello,

I am making a slice along the Y-normal plane. However, I would like to look at results confined to a region bounded by an elliptical surface. The region I want to visualize is restricted to where x^2/a^2 + z^2/b^2 < 1 (i.e. inside the elliptical region). I am assuming I need to leverage the Threshold filter, but I I just don’t know how to make it happen.

I tried a quick search in the Support group but could not find a relevant thread. I am somewhat of a beginner, I don’t do python programming. Help would be greatly appreciated.
Thank you.

You can follow the Slice filter with a Clip filter, setting the Slice Type property to “Sphere” to get a spherical region.

For an elliptical region, you might first need to define a distance field using either the Calculator filter or Python Calculator. You can use an implicit elliptical equation in the calculator expression to do this. Then, use the Clip filter, but set the Clip Type to Scalar and set the Scalars to the new array computed by the calculator filter.

Hello again,

Many thanks for your response. The clip filter with a sphere worked and it was very straightforward. I am having trouble with the Calculator filter. The equation for the ellipse which I am interested in, I entered as follows in the calculator: X^2/(13.8e-3)^2+Z^2/(9.1007e-3)^2=1. But, when I enter Apply, I get error messages which I have pasted below.

I then used:

coordsX^2/(13.8e-3)^2+coordsZ^2/(9.1007e-3)^2=1

That didn’t generate error messages. But the result does not look like anything I expected.
I also found the following thread. I am not sure how relevant it is to the problem at hand: slice along polyline

Just to clarify: Am I supposed to do a clip at Y-normal, and then create the calculator with the elliptical equation, followed by the scalar clip?
sphere.tiff (2.6 MB)
What I want to see is the elliptical equitvalent of the attached plot.

Thank you.
Maziar.