Thoughts - PGS to EVS Precision Needs To Be A Reality.
If you've followed my recent posts you know that there is a great deal of interest in the NGA PGS map product. I had earlier reported that EarthSat had worked 300 man-years on the map files. According to my source, that number was not accurate. The individual I had spoken with had miscalculated. In actuality, they spent 13 man-years on the project. That is still a tremendous investment in time and effort.
To keep my readers abreast of my efforts relating to this database, I do have the NGA PGS database, all 28-files, loaded into my mapping program, Marplot. I use them exclusively when I am working on projects at 1:125,000 and larger. I move portions of them into Global Mapper and Google Earth Plus when I am digitizing shorelines and I require a frame-of-reference. The details that are available in the NGA PGS data are excellent.
I have also converted the Region-6W of the NGA PGS data into KML/KMZ, Google Earth (GE) format, and posted it to GE. It looks great on GE often turning some of their blurry images of islands into recognizable shapes. See my post entitled, How To Convert PGS Map Files into KML/KMZ. I also do comparisons of various shoreline map files, Comparison: PGS, WVS, EVS and 1-Meter Shorelines.
I am sure most of you are aware of my push to take the NGA PGS data to the next level, what I call Enhanced Vector Shorelines or EVS. My post entitled, How To Adjust PGS to EVS Precision - An Example and Thoughts, discusses how to make the adjustments and concludes with my ideas on how this might happen for the entire data set, that is converting PGS to EVS precision.
I know that EVS precision is cartographically sound based on a side-by-side comparison I recently completed using a Land Information New Zealand topographic map and my own EVS version of the same island (Palmerston Atoll). At a scale of 1:25,000 the LINZ map and EVS map are nearly identical. This leads me to conclude that EVS precision can often result in a map product useful at 1:25,000 scale.
I am adamant on two points regarding the NGA PGS map files:
1) They are, without question, the most precise representation of global shorelines available to the public.
2) Realizing that they are Prototypes (needing refinement), PGS should be refined to EVS precision in order to provide the most accurate, finished shoreline possible, derived from Landsat-7 ETM+ 2000 imagery.
So goes my quest to make this refinement a reality.
