Waveshare explain yes to both those things...what happens next?

H I've bought the 800×480, 7.5inch E-Ink display HAT for Raspberry Pi after seeing a couple of examples of people managing the view the terminal via e-ink products. At the current stage I'm only with the idea itself, so. I was hoping you could enlighten me and somethings I should perhaps understand ...

After following this blog: https://zbigatron.com/mapping-camera-coordinates-to-a-2d-floor-plan/ there are a couple of things I could do with more support on as there are somethings I'm not entirely clear on. There is an instruction about obtaining coordinates using gimp? So I think this means when y...