In Search of Efficient Motion

Hmm. There are large chunks of perfect reconstruction and other chunks of absolutely false positives. This bridge is being shut down to be repainted the beginning of next week.

I'd like to capture it as it was before that happens and compare it to afterwards but I'm still searching for a way to systematically cover it efficiently but thoroughly. As it stands I only stopped shooting the day before yesterday because my battery ran out.

My swivel technique provides great results but unfortunately is also very expensive in terms of numbers of photos for both my memory card as well as image features for scene reconstruction. As things stand I would have run out of space on my card soon anyway and I had only shot half the bridge, if that.

Later today should provide enough data to tell me whether I can get a high enough quality reconstruction purely from the strafing parallax that I started experimenting with towards the end of this shoot.

Shooting both sides should provide opportunity to flow far more smoothly with the coverage with a few less shots as well. I am also currently debating whether I should continue the method of getting a complete vertical pan at each position before moving sideways to capture that or whether I might meet with better success by simply using a continuous horizontal pass across the entire length of the bridge at each vertical angle, starting looking from eye level forward, moving to looking slightly upward, further upward, and straight up.

One thing I know for certain is that I'll be packing a tripod this time.

It would be amazing to be able to get shots from a boat on the river, providing semi-circular routes around each side of the bridge as well as full orbits of the supporting pillars, but I don't know if I can find a boat in time. The ultimate would be getting helicopter coverage, but that is extremely unlikely to happen as I am flat broke. =]

The challenge with a structure such as this is to provide coverage that will clearly define each major line in the bridge. They all spend so much time overlapping and there are just so many of them that the # of photos that seems necessary to get a decent approximation of each quickly skyrockets into dangerously high #s for the synther to successfully process. Taking enough photos for closeups of each beam results in an unthinkable # of photos. Add to this that there are parts of the bridge which in structure are symmetrical and you have a full blown mess.

The texture on these identical parts should be enough for Photosynth to tell them apart but I'm being forced to stick to wide shots, rather than go in for closeups, so the texture analysed by the time the synther shrinks the photo down to 1.5 megapixels for matching is negligible and I did witness several places where in jumps back and forth in the structure where I continued on a smooth course in real life