# Curve resemblance to Closest Shape - Question on Hold - Advice for clarification needed

I need some help figuring out how to make this post more clear. I've addressed the comments for clarification, but it looks like people still don't understand my question?

I stated the question originally in terms of five known points, from which one can interpolate a curve. I am trying to determine how to match the curve to four basic shapes.

Given five points on a face, determine if the "face shape" is closest to a circle, oval, square, or triangle

Any insight on how to make my question more clear is appreciated.

• I'd say the biggest problem is that you don't have a good definition (in the question, at least) of what "closest" means. As in: if I hand you a list of five points, you ought to be able to tell me some specific number quantifying how far it is from a circle/triangle/oval/square and be able to make a choice about what the best number is. This is close to the idea of Ross Millikan's comment about the metric you're using.
– user296602
Mar 29 '18 at 21:13
• I personally think it's rather clear what's being asked (then again, I was just at an optometrist, and saw a similar face-shape chart, recommending lens shapes based on face shapes). I could perhaps see "too broad" as a valid close reason. The fact that you don't have a method/formula for measuring "closeness" seems to be exactly the point of the question... Mar 29 '18 at 21:36
• @pjs36 what a great coincidence. i am as an indie developer building a product for optometrists (or primarily end-users who purchase a lot of eyewear online, such as myself). i've used a variety of just 2D graph curves to try measuring the face shape but was hoping for more advanced insight here
– ina
Mar 30 '18 at 0:31
• @user296602 i've heard of metric in definition to things with jacobians and also in relativity. are they suggesting that i first need to define some sort of eigenspace for each of these shapes? it isn't clear to me how the metric applies here
– ina
Mar 30 '18 at 0:32
• @user296602 do you think i should ask a corollary or pre-ceding question for metrics that define these basic shapes?
– ina
Mar 30 '18 at 0:36
• @ina "Metric" is just another word for "Distance Function". It doesn't have to be defined on a vector space. Mar 30 '18 at 15:52
• Read the comment of @user296602 more closely, particularly the emphasis on a number (the word "metric" refers to the method of specifying this number, not to eigenspaces are jacobians etc.). One reason why your question was closed is that without specifying such a number, nor acknowledging the importance of such a number to your question, the mathematical basis of your question was deficient. Mar 30 '18 at 16:08
• I think that inventing a suitable metric is the whole point of the question. Once you have a metric, the rest is just boring calculation. Apr 6 '18 at 10:36