EVS-Islands

Haifa Harbor - DigitalGlobe Image from Google Earth (1:4,600)

Let's begin this comparison of shoreline accuracy by superimposing four shorelines onto a 1-meter resolution image of Haifa Harbor. Why Haifa? Just because I happened to be making a land-sea mask in this part of the world. My initial study focused on using NGA's Prototype Global Shorelines (PGS) created from Landsat ETM+ imagery. As you will read and see this global shoreline is one of the most detailed available. It does have a few negative considerations, like "stuttering" shorelines, non-mapping of water-inundated land (swamps, marshes, etc.) and hand-tracing of shorelines is more accurate than the software generated shorelines...but, that said, NGA PGS shoreline is a great first-step toward a global shoreline for all of us.

Haifa Harbor - 1:2,000,000 (Red) and 1:250,000 (Blue) (1:4,600)

The 1:2,000,000 (Red) shoreline is, by virtue of it's name, designed to be used at 1:2,000,000 or smaller resolutions. It works well for coarse shoreline delineation to get "an idea" of where the shore ends and the sea begins. The 1:250,000 goes by the acronym W(orld) V(ector) S(horelines). It was originally extracted from Tactical Pilotage Charts. It gives one a useful shoreline for a wide variety of projects. However, when one pushes it beyond 1:250,000 it quickly proves inaccurate in tracing the actual shoreline.

Haifa Harbor - NGA PGS (Yellow) and EEVS Precision (Lite Blue) (1:4,600)

Now for the good stuff! The NGA PGS precision shorelines do a fairly good job of tracking the actual shoreline. They are deemed appropriate at scales between 1:125,000 to 1:250,000. Some areas could be pushed to 1:62,500, but be careful. I am careful and I push them below 1:62,500, for digitizing purposes, in order to confirm my Landsat derived hand-made vectors are of greater precision than the PGS. And mine are! For the purposes of this comparison the PGS shorelines would give a person an accurate shoreline impression as long as it was not superimposed over the actual shoreline. The lite blue line is what I call E(xtremely) E(nhanced) V(ector) S(horelines). They are derived from DigitalGlobe's 1-meter resolution imagery found in Google Earth. Oh, that all the world were imaged at 1-meter cloud-free resolution. I feel that is a long way coming and I don't think the global shoreline vector files derived from them will be free. I suspect they will be quite costly.

Back to the land-sea mask, or what started this current study. The most accurate vector based global land-sea mask is mine. I call it GSHHS Derived Global Land-Sea Mask and you can download a copy here. Be forewarned, the file is 83.9MBs zipped and 340MBs unzipped.

The most accurate future global shoreline map should be the NGA PGS precision product, but it needs work to finish it (correct stutters, map non-mapped areas, etc.). Once it is finished, it will be THE GLOBAL SHORELINE. Until then, WVS rules.

Enjoy!

Labels: Land-Sea Mask, NGA, PGS, Tactical Pilotage Charts, WVS

Posted by Mr Minton at 11/25/2007 07:43:00 AM | Permalink | Comments | links to this post

Just Thinking About It

Back in 1964, I was checking out reference books at a library. I happened upon a Geographical Dictionary. Leafing through that dictionary, I came upon an entry describing a small obscure island, Eiao. The entry stated that this island was 8 miles by 4 miles with elevations of 3,000 feet in the island's central plateau. At one time the island was inhabited. During the later part of the 19th century, the French used the island as a prison. Now the island was overrun by feral animals which were decimating what little native vegetation remained.

From that single incident came my fascination with islands. Like many people with a keen interest in islands, my reasons are many and most of these reasons having nothing to do with geography (stress, explorer, master-of-my-domain, etc.). What I discovered early on was the absence of readily-available maps. There were a few WW-II maps in out-of-print books, but no available collection of island maps.

Scripps Institute of Oceanography and Maps

That led to Scripps Institute of Oceanography and their excellent map collection. SIO does ocean-oriented research throughout the world. Consequently, they have a paper map collection of the world oceans and islands that rivals the best in the world. During the early 1980s, I spent many weekend hours pouring over this collection of maps and charts. The map librarian and I became acquainted and he allowed me access to their entire map and chart collection. It was both a joy and a curse, a sensory overload. I had access to every island paper map in the SIO collection and all I could think was, "So many islands, so little time."

My first idea was to amass my own collection of paper maps. This was the pre-digital and pre-affordable computer age. I would need to copy thousands of maps. No way! At 15 cents a copy, it just wasn't practical or affordable. I thought I could trace the shorelines of islands. Too many islands, too complicated, too time-consuming. Again, No way! So I stopped. That's right, stopped any island map aquisitions activities and went about my non-island map life.

Affordable Computers...

Which takes us to the late 1990s, the time of affordable computers, mega-storage, www and information everywhere. This was a time of digitizing paper map collections and one of the first was the Perry-Castenada Map Collection at the University of Texas. I'm not sure of the precise date that their collection went on-line, but many paper maps were freely available as raster images. Anyone could download them and amass their own digital map collection. During this time, I downloaded 100s of island maps. It was great fun, but I knew there was more. Raster maps were okay, but what about vector maps. They were considerably smaller in size and offered greater flexibility. In 2001, I went the way of the vectors.

The Way of The Vector

Not having money to spend on software, I became the master of the freeware and shareware world. I finally settled on Marplot for my mapping software and World Vector Shorelines from the NGDC Coastline Extractor. I remember downloading 100s of vector tiles onto 1.4MB floppies, taking them to my computer where I uploaded them into Marplot. It took about a month and I managed to load all of the world shorelines at 1:250,000 scale, 20,000+ placenames of major cities, 86,000+ placenames of islands and various other opportunistic layers of information.

Free Landsat ETM+. Global mapper and Google Earth

It was about three years ago that I discovered free Landsat ETM+. Turns out Bill Clinton, at the urging of Al Gore and others, made Landsat ETM+ georectified photo mosaics available for free. I spent that summer downloading all of the Landsat ETM+ images that covered oceanic islands of the world. It was at this time that I actually spent hard currency on my mapping passion and purchased Global Mapper. This software can load Landsat ETM+ in MrSid format effortlessly and has an above average digitizing toolkit. The final piece to my mapping project puzzle was Google Earth with DigitalGlobe imagery. As more and more hi-res imagery comes online, the quality of my work will be greatly enhanced.

What Now? Just Do It!

Since 2004, I have been making island maps. Since 2005, I have been posting my island maps on to my blogsite. Since 2007, I have been producing high-quality vector maps of islands. To date I have produced close to 200 maps covering easily 1,000+ individual islands. People ask why I give these maps away. They suggest that I need to charge for my work. I say to them, "We'll see." What I mean to say is, "No, I will not charge for my raster images of maps." If you want them, you can download them and use them. Just give credit where credit is due.

Today and In To The Future

I would love to guide an international team of neo-cartographers to complete a world shoreline map, including islands, using Landsat ETM+ imagery. Yes, I know all about the NGA Prototype Global Shoreline. Trust me, my world shoreline will be more accurate. I would love to guide that same team of international neo-cartographers in fashioning the next-generation Digtal Chart of the World. I would love to make all of this information available for free. In the spirit of Google, free.

So that is what I do. I continue to make high quality island maps and post them to my website. I continue to actively solicit serious offers toward sponsoring a world shoreline mapping project using an international team of neo-cartographers. This passion is what drives me forward. And forward is always the best direction to be moving.

Enjoy!

Labels: DCW, DigitalGlobe, Eiao, Google Earth, Landsat ETM+, Marplot, neo-cartographers, NGA, PGS

Posted by Mr Minton at 8/25/2007 08:12:00 AM | Permalink | Comments | links to this post

Orkney Islands UK

This is a preliminary map of the Orkney Islands. So far I've used MS Live Local imagery, Landsat ETM+ imagery, NGA Prototype Global Shoreline and World Vector Shoreline to complete this first look at the Orkneys. Landsat ETM+ is largely cloud-obscured and only workable for the southern portion. MS Live Local uses some proprietary imagery that acts alot like Landsat, but I'm not for sure. NGA PGS makes up the northern end of Scotland and WVS was used as a check against other vectors. The project started with a viewers request for bathymetric data. He got the data, but the shorelines were WVS (1:250,000). My mapping is better than WVS, but not EVS quality. It is good, but not great. More will be coming on the Orkney's.

Enjoy!

Labels: EVS, Global Mapper, island, Landsat, Marplot, MS Live Local, NGA, Orkneys, PGS, UK, WVS

Posted by Mr Minton at 6/08/2007 12:38:00 AM | Permalink | Comments | links to this post

Malta - DigitalGlobe Image from Google Earth (1-50,000)

The first part of this post is called "Mapping Malta". Not necessarily a big island, but the shoreline has been quite a challenge to digitize. I am about 3/4's finished with the first pass using DigitalGlobe's imagery from Google Earth as my base and the digitizing capabilities of GE to map the shoreline. In the process, I have mapped moles, groins, breakwaters, quays, piers, slipways, ramps and a few dry docks. Thanks to DigitalGlobe's fantastic imagery, my shoreline mapping challenge is greatly magnified. But that's okay. Once this shoreline is finished, it will be a WOW!

Malta - DigitalGlobe Image from Google Earth (1-6,250)

Malta - DigitalGlobe Image from Google Earth (1-3,125)

Malta - DigitalGlobe Image from Google Earth Detail Shoreline (1-2,500)

The three detailed shoreline images above are extracted from the southern side of Malta. The coast appears to be made up of a base rock layer that sea and air manages to split apart and gradually weather these rocks into pebbles after many, many years. The rocks on the last images are very large. The rectangular-shaped boulder is over 17-meters by 17-meters! If that rock were in the sea, alone, it would be an island. Based on my mapping criteria, it is part of the shoreline. How should I classify this portion of the Malta shoreline? Rocky? That doesn't do it justice. Big Rocky? Better. Lots of Really Big Rocks Scattered Within 100-Meters of the Unfragmented Shoreline? Now, I like that name. I will work on the nomenclature to transform "wordy" into a succinct EVS label.

Malta - Landsat Image N-33-35_2000 Detail Shoreline (1:2,500)

I couldn't leave this post without giving you Landsat ETM+ 2000's comparable image of the same shoreline area. Digital Globe's HiRes imagery is amazing, from a mapper's perspective. The most accurate global shoreline freely available, NGA's Prototype Global Shoreline (PGS), approximately tracks the Landsat ETM+ shorelines. It is an impressive effort that will be useful in a wide variety of projects. But when you compare it to Digital Globe's derived shorelines - Forget about it! As you would expect.

Enjoy!

Labels: DigitalGlobe, EVS, Global Shorelines, Landsat, Malta, NGA, PGS

Posted by Mr Minton at 5/23/2007 11:15:00 AM | Permalink | Comments | links to this post