Oh wow, I hadn’t heard about Sensel, but I will definitely be preordering one.
Re: touch/pad/images, it’s worth noting that the Linnstrument isn’t actually implemented as discrete pads-- it’s not a tabletop Eigenharp. Each row is continuous, so you can pitch-bend smoothly across the whole thing, and you can articulate up and down within a row regardless of where the touch originated, and regardless of where you’re gesturing. I was informed, however, that the rows are discrete in hardware, so it isn’t fully 3D in the way that the soundplane is. (I haven’t tested, but I’m guessing that you can’t bend two touches in the same row together and still distinguish y-axis movement between them, but maybe you can?)
Anyways, you will have to do some kind of blob detection, tracking, and separation if you roll your own. It’s non-trivial stuff for sure. At the cost of the Sensel, I’m personally happy to punt that hard work to them and figure out how to adapt it to my interests 