04-05-2017, 07:22 AM
Just a comment: the "sketch a curve" feature tries a bunch of fits and then decides between them by taking into account a geometric measure of distance between the user-drawn curve (which is, for these purposes, just a collection of point samples) and each potential fit curve (and the type of potential fit, as a simple direct comparison of geometric distances would strongly prefer fits that have greater geometric flexibility [as Han alludes to with his comments on polynomial fits]). The geometric measure looks at how far each user-drawn pixel is from each potential fit curve. "How far" (for each user-drawn pixel, for each potential fit) is a two-dimensional search. (Treating the two dimensions homogeneously, here, is fairly reasonable given the nature of user-drawn curves. That may well not be so for some data sources / applications.)