Project 2D image on a surface

I'm building a web app that projects a 2d image on a flat surface. For this to work I need a marker that I can recognize on the surface.

My idea is to use the QR code finder and alignment patterns as a marker to figure out orientation, distortion and distance. The orientation and distortion part is easy with QR codes. For the distance I thought that I can print the finder patterns with a fixed distance between them of 1cm and calculate the distance to scale the image accordingly.

Now I have 2 questions:

• Is this a good approach?
• Is there a better way or marker that I can use to achieve the same thing?