Mar 25 2009
Terrain has been in the mix for me quite a bit these past four weeks. I’ve worked on pushing ESRI ArcGIS 3D Analyst to its limits of masspoint digestibility, trying hard to bring everything into focus at the same time that everything is sinking down to NAVD88 datum. An abundant set of waterlines and terrain breaklines have helped to make possible some terrain models that appear to be as good as any one is likely to get from photogrammetric data. As with LiDAR source, I’m working toward a 30cm gridding interval to sample any reasonable-looking TIN models.
One fascinating aspect of the terrain model is where it ends. There appears to be a new 1:1200 or 1:4800 shoreline that can be sussed out of some combination of 2.5-foot elevation waterlines, 2-foot elevation contours, and related artifacts. In fact, it’s a great patchwork of artifacts that must be stringed together. In the tidal flat areas, there is also plenty of need for validation with multiple photos (hopefully shot at times of lower tides).
Adding to the data bulk there’s a new ortho in town, 30cm natural color flown just about two years ago. There’s hope of extracting it from the grip of California HARN coordinates after it is all mosaicked.