I need to find out if Plane is Concave or Convex. Any ideas?

three planes, circle patterns of hits, concentric, small ring, medium ring large ring, if the hits are higher in the small ring then you are in trouble.

However, I'm not sure what your resolution and repeatability is on your CMM to distinguish between the hits if the part is convex by .00005.

Light bands if it is flat enough and reflective.

Make them intentionally .0002 concave so you can test it with an indicator fast and easy.

mkk177 Since you're running PC-DMIS 2023.1, you could use the Geometric Tolerance command to do profile of a surface with an unequal tolerance zone. You would need to reference the plane as the primary datum as well as the considered feature. If you're working to ASME Y14.5, you would need to apply a total tolerance of 0.0004 with a U value of zero (no positive tolerance). If you're working to ISO 1101, you would apply a total tolerance of 0.0004 with a UZ of negative 0.0002. Regardless of the standard selected, your deviations and graphics will come from the centre of the tolerance zone (so 0.0002 below the surface of the plane).

I have to agree with Caemgen on the resolution though. Assuming that 0.0004 value is in inches, that's only 0.01mm (10µm). Unless you have a very accurate machine with a first term uncertainty of 1µ or less (like a Leitz PMM for example), you will struggle to get reliable results.

If you have scanning capabilities, you might try to scan a line on the plane where you want to check for concavity or convexity, maybe in multiple spots. Use the points to construct a circle with BFRE. The calculated circle will be very huge, but depending on the diameter and location of the center point (way over or way under the plane), you might determine whether the plane is convex or concave.

I would do it with a sphere from all the plane hits

Using this technique kind of gives me a result that shows the NG issue. I get 0.0003 positive and -0.0001respectively. however, it has a total of 0.0005. Flatness is at 0.0001. I even changed the total tolerance to 0.0005 only to get a reading of 0.0006. I will check several parts and find out how well it works

thanks

Yes you can extract the sphere's z centroid. anything above the plane (z+) would be Concave, anything below the plane (-z) would be Convex.
Push z value into an assign, and make a static text output. if=(sphere1.z>0,"Concave","Convex")
report output the assign value. boom