EVS-Islands

It would be so easy to become discouraged in my quest to map the world's shorelines using Landsat ETM+ 2000 imagery when one views the above comparison. That fuzzy blob in the first image (Landsat ETM+) was initially mapped, by me, as an unknown feature just offshore. The straight lines and the faint connection to the shore suggested some sort of docking facility. The same feature at 1-meter resolution is easily discernable is a docking facility with numerous ships and boats scattered about. Okay, 1-meter resolution is great, but it isn't freely available like Landsat ETM+ is. For shoreline work the 1-meter resolution does such a great job at illuminating all features both above and below water that it creates mapping decision problems galore. It does such a great job that the decisions as to what to map become magnified to an awesome level. My simple decisions - "Where is the shoreline? Is that a rock or a pier? Is that feature underwater or above water?" - become much more complex. Working by myself, as I do, little mapping would be finished. I would still be pondering my first island and trying to determine the most precise line of information to digitize. Don't get me wrong. I love 1-meter resolution imagery. I think it is cool to see the exquisite details that this sort of imagery gives you. However, when you are making shoreline maps that are intended to improve upon 1:250,000 scale existing shorelines and you try doing that with 1-meter imagery - that mapping becomes too complex, expensive and time-consuming for a 1-man operation. Others might be able to use 1-meter imagery to make maps , with unlimited resources and money, but that isn't me. My mapping is done in my den on my Sony Vaio viewing a 17-inch flat screen. I use a wireless mouse to trace digitized lines from on-screen imagery. I listen to classical music as I map. Sometimes I map and watch a baseball game (Go Padres!). All of the Landsat ETM+ 2000 imagery of all of the world's shorelines is either on my hard drive or on DVD's in a storage case resting beside my workstation (desk). I can greatly improve on the 1:250,000 shorelines that are currently available. In fact the United States shoreline is mapped at 1:70,000 and my maps are able to either match or improve upon these shorelines as well. Yes, 1-meter resolution imagery is great for many viewing and mapping needs. But not for my project. Landsat ETM+ at 14.5-meter resolution (depending on which continent you are viewing) is just fine for me. Hopefully, for you as well. Enjoy my maps! OT: Images

Posted by Mr Minton on Tuesday, May 02, 2006 at 5/02/2006 07:22:00 PM | Permalink