I think, the spokes are a good approach, since these are actually objects recorded in time. However, I think @gorgoiler [1] has made a valid point regarding th

I think, the spokes are a good approach, since these are actually objects recorded in time. However, I think @gorgoiler [1] has made a valid point regarding the intersection of the "finish plane" and the plane recorded by the camera. (On the photo shown on your blog, the camera appears to be mounted slightly behind the finish line, thus, intersecting the "finish plane" at the ideal height, should point to just before the finish line at ground level. But there isn’t sufficient information in the photo to measure such a minimal angle, or to confirm, if there's any at all.) [1] https://news.ycombinator.com/item?id=26977975 https://news.ycombinator.com/item?id=26977975