Raster vs Vector - An Explanation
The previous post was for the benefit of the true mapping neophyte - that individual that looks at a picture with no considerations for the inherent limitations that picture has for a mapper. Digitizing off of Landsat ETM+ 2000 imagery has well documented limitations. I typically work at about 1:10,000 scale where I can consistently depict ground features. God forbid, I should get clouds mixed in as well. If you should recklessly try to zoom in to a scale of 1:2,500 using Landsat, you do not improve your digitizing efforts, you degrade your product. I have digitized 1,000's of miles of shoreline and realize that Landsat product is a static image taken from a satellite orbiting high above and it will render a dynamic geographical entity (shoreline) imprecisely for many traditional mapping purposes (coast & geodetic surveys, marine surveys, property delineation). However, when you want to dramatically improve upon World Vector Shorelines (WVS) at 1:250,000 scale, you can using Landsat imagery! My Enhanced Vector Shoreline (EVS) maps, typically digitized at a scale between 1:25,000 to 1:10,000 (depending upon the quality of the image), are such a radical improvement over WVS that I will never be satisfied to use WVS mapping for anything under 1:250,000. And even that is coarse rendering of shoreline details when compared to EVS map files. Do I suggest that my maps handle the dynamic shoreline with total accuracy. No, they do not. Do I emphatically state that my shorelines for many of the areas I have mapped are the best renderings freely available. Yes! Do I realize my mapping prowess is a constantly evolving set of special skills. Yes! Do I know that other processes, other software could produce equal or superior product. Yes! I like to make maps! I like to make excellent maps that can be used in a variety of situations. Show me the better way and I will adapt. Show me the faults of my work and I will adjust to correct. In the mean time, I will continue to make the best maps possible using the processes that I am perfecting. Enjoy my maps! I do. OT: Special Topic
