Just as a follow up to this re: accuraccy.
I had a job come in this week that was recreating shelves from a limo's bar. Since we have 12x12" tiles, I used those as my reference and just used my phone camera (I did have some barrel distortion but I deemed it not enough to look up how to correct).
My process was:
1) Take photo. obviously as straight above and straight at the floor in this case.
2) bring into GIMP editor. I think the more modern corel can do this, but my computer is running x5 and I didn't see the right stuff.
3) crop close to, but slightly wider than, the reference corners. In my case, a 2 x 2 or 2 x 3 grid of the tiles. Ideally, the reference shape is larger than the shape to trace.
4) Shift-P for the perspective transform tool. Bring the 4 corners of the gird that shows up in-line with your reference corners.
5) Apply the tool and save the result.
6) Load into Coreldraw or other vector program.
7) Scale the photo to the size of the reference shape (24 x 36" for most of these for me)
8) Trace the shape and cut a test.
All pieces were within 1/8", I will cut final pieces with holes for cupholders from the traced shapes. If I obsessed on the tracing (or actually traced the parts and used the picture which would be flatter) and reduced the barrel distortion, I think 1/16" or better accuracy would have been possible.