EVS-Islands

Shoreline Map Comparison - Yahoo, Google, MS and EVS Precison

Shoreline Map Comparison - DCW and VMAP0

This post shows that Google Maps, Yahoo Maps and MS Live Search Maps use DCW/VMAP0 global shorelines for their mapping, at least in the area of Rabul. That is 1:1,000,000 scale global map coverage. James Fee, a well-respected GIS professional, commented, "When it comes to precision, I think the efforts for GYM (Google, Yahoo, Microsoft) should be on the navigation/geocoding/routing and not shorelines." First, one must agree with James' statement that GYM's maps are intended primarily for navigation/geocoding/routing. I believe that their customers, global in reach, would subject GYM's maps to many other GIS uses beyond navigation/geocoding/routing. I know that there is an agressive effort within the GIS community to provide a richer, more powerful set of tools, allowing any of us the opportunity to explore more complex spatial issues using Google Maps and Google Earth as platforms of choice. Ultimately, the end user, faced with a spatial problem requiring small scale maps would either have to make their own map, pay to have a map made, use a substandard map in place or not use a map at all.

In addition, James seems to suggest that 1:1,000,000 scale is satisfactory for GYMs primary efforts of navigation/geocoding/routing. I understand his reasoning, but I disagree. Before teaching, I did extensive geocoding of environmental risks. Locational precision was critically important. 1:1,000,000 was an unworkable geocoding scale. To follow the flight path of an enemy aircraft using 1:1,000,000 is doable. However, to locate enironmental risks at that large of a scale is asking for problems. A misplotted environmental risk could well result in a lawsuit. Business locations was another area I worked in and locational precision determined an exclusive market and was a contractual promise to the franchisee.

James goes on to say, "For me the shorelines are somewhat irrelevant to the routing provided. If I do need good shorelines, I'll probably just be using the aerial imagery in the first place." Again, his reasoning seems to make sense, but I disagree. First, shorelines are not somewhat irrelevant, they are a dynamic boundary between man and water. A raster image of a shoreline is practical for some applications, but a vector defined shoreline offer one a wide range of mapping possibilities. If I am GYM's map guru, I want my customers to have the greatest mapping precision possible. I don't want to impose precision limitations when there is no need. EVS precision shorelines, on a global scale, requires money to fund the mapping effort and time to complete the project. It will be money well spent. The resulting shorelines and other feature/land use layers will allow the "G", the "Y" or the "M" to be the number one mapping destination for all users and that could generate lots of ad dollars.

Finally, vector maps allow for infinite zooming with no lose of detail. If the initial vectors are created from quality base imagery (i.e., Landsat ETM+) and the map customers are able to easily access these detailed vector maps, they can tackle complex spatial issues using GYM's hi-precision mapping. Thus a marketing boon to the company savy enough to provide the product.

Enjoy!

P.S. - After yesterday's post, I received a query from an individual about EVS precision mapping for a section of Canadian shoreline. He had used WVS/GHHS vectors and they were unsatisfactory for his project. I sent him NGA PGS vectors covering his target area. They looked okay at 1:250,000 scale. He loaded them and acknowledged they were a significant improvement over the WVS/GHHS vectors, but were angular and did not track a cloud-free shoreline as one would expect. I created EVS precision vectors for him. He compared them to NGA PGS vectors and immediately acknowledged their higher quality. He asked if I would go ahead and create EVS precision vectors for his entire study area. I will, but wouldn't it have been cool for him to go to one of the big three mapping portals and find this mapping not only available, but downloadable? I think so.

Labels: DCW, Google Earth, Google Maps, GSHHS, MS Live Search Maps, NGA PGS, VMAP0, WVS, Yahoo Maps

Posted by Mr Minton at 6/25/2008 09:34:00 AM | Permalink | Comments | links to this post

Shoreline Map Comparison - Yahoo, Google, MS and EVS Precison

Whose shoreline maps are currently the most accurate? Is it Google Maps? They have loads of bucks and a keen desire to put the best product into their sites. They must have the most accurate shorelines. Right? Nope, not them. Yahoo! Maps, the current darling of the stock market and Google "wannabe", has the same clunky shoreline used by Google. MS Live Search Maps has the prettiest maps. Lots of shaded hills and valleys, but clunky shorelines. For sure, MicroSoft must have the most accurate shorelines. For sure, not.

Would you believe, EVS Precision Maps has the most accurate shorelines compared to the big three map moguls. EVS precision mapping is derived from Landsat ETM+. Typically, it provides accurate shoreline depiction at scales between 1:100,000 to 1:50,000.

Rabul - MS Live Search Map

All map maker struggle with PPL (populated place) placement. The PPL data is available through NGA. I'm reasonably certain most of their data and locational information was derived from ONC (1:1,000,000) charts. Looking at the PPLs on the MS Live Search Map of the Rabul area, we see towns lined up in a grid. In the real world, this only happens in the midwest, not on New Britain Island in Papua New Guinea. One should replot these PPLs using Landsat ETM+ or hi-res imagery. The only thing certain about the above plots, is their locational uncertainty. But, back to shorelines.

Rabul - EVS Precision Maps

EVS Precision Maps provide the most accurate shoreline maps of the four being compared. The big three use, what appears to be DCW's 1:1,000,000 shorelines. 1:1,000,000 has it's uses, but when one zooms to 1:63,500 (1" to 1-mi), a shoreline that approximates reality is expected. EVS Precision Maps show that expected shoreline. Google Maps, MS Live Search Maps and Yahoo Maps do not.

Enjoy!

P.S. - I am aware of NGA PGS vector files, 24 tiles covering much of the world. They were derived from Landsat ETM+. EVS Precision Maps and NGA PGS should parallel each other. They do not. NGA PGS vectors used a digitizing algorithm to automate their work. Peculiar stutters, uncalled for strings of vectors and angular shorelines are often the norm. Also, NGA requested that water inundated areas (swamps, marshes, tidal flats) be excluded. This caused a great many problems in shoreline mapping. Also, the slightest cloud cover often thwarted their automated digitizing efforts. EVS Precision Maps consistently improve upon NGA PGS.

Labels: DCW, EVS Precision, Google Maps, MS Live Search Maps, NGA PGS, Yahoo Maps

Posted by Mr Minton at 6/23/2008 08:25:00 AM | Permalink | Comments | links to this post

I was explaining my mapping work to a person I met at a party earlier today. This individual asked all of the right questions ( What do you do? Where do you get your images? How do you digitize the shorelines? What do you do with your finished maps?) Poor guy! I answered every question with a detailed, lengthy and somewhat technically boring response. After my fifth lengthy reply, he excused himself and joined another group.

As I reflect on my exchange with this curious person, I am amazed at the breadth of my knowledge and convinced that I can be very boring. I really do know quite abit about digitizing shorelines. After a few thousand kilometers of continental shorelines and 9,000 island shorelines, I am able to digitize a precise shoreline (within the limitations of Landsat ETM+'s 14.5-meter resolution).

Early on, I had professional cartographers tell me my maps would be useful at 1:125,000 to 1:63,500. I have learned that my island shoreline maps are useful at scales well-below these upper limits. I typically post completed maps at 1:25,000 scale. After adding layers of information, they work well for an individual attempting to determine a relatively coarse view of an island. Landsat is not DigitalGlobe's hi-res imagery, but it does a great job at giving one a highly resolved broad view of a geographical area.

New Britain PP - Digitizing from Landsat S-55-05_2000 (1:19960)

So, how is it that I do what I do? In digitizing, that is. The above image shows a typical stretch of large island shoreline. An attempt to generate vector shorelines from Landsat ETM+ was done a few years ago. This data, called NGA PGS, is fairly good at defining a shoreline, but coastal swamps are excluded causing some very strange looking maps of islands. If the island or shoreline contains water-innundated shoreline, NGA PGS does not map it. They could have, but someone, somewhere thought it would be good to exclude it. My shorelines include these water-innundated areas. The red line in the above image is my completed EVS precision shoreline. Except for the final vector which I purposely placed in the sea, the shoreline is much more accurately delineated than NGA PGS, WVS, DCW or any of the other available global shorelines. I am not saying EVS precision shorelines are global yet. I am an optimist. Someone, somewhere, sooner than later will fund my mapping efforts and the result will be a global shoreline at EVS precision.

Enjoy!

Labels: DCW, digitizing, EVS Precision, NGA PGS, WVS

Posted by Mr Minton at 6/07/2008 10:46:00 PM | 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.

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

Comparison of Four Different World Vector Shorelines

If you look at most commercial digital atlases, their data is based on Operational Navigation Chart (ONC) data, which was originally compiled and maintained so that pilots could use these maps as reference tools when viewing features from 20,000 feet. They worked well for their intended purpose and were reasonably maintained. They were largely fashioned from pre-satellite data, much of it derived from aerial photography dating from WW-II through pre-Vietnam. Any cartographer worth their mapping "salt" will tell you that much of the data is, at best, only moderately accurate. ONC shorelines are close to actual shorelines, but not very close. The ONC shorelines were never intended to mirror the actual shoreline. I mean the scale is 16-miles to the inch!

So from this data source a product called Digital Chart of the World (DCW) was produced. Every atlas company producing small scale mapping uses some or all of the DCW data. Since my area of focus is global shorelines, I can state with certainty that if DCW shorelines are used in a map product, those shorelines are only moderately accurate. But for many map users, moderately accurate works. My Michelin maps got me from city to city and allowed me to navigate with a solid degree of certainty.

World Vector Shorelines, at a scale of 1:250,000 (4-miles to the inch), were fashioned from Tactical Pilotage Charts and other similar sources. Their shorelines are more accurate than DCW/ONC shorelines. However, they also more often miss the shoreline than track it.

Landsat ETM+ 2000 Coverage

Now we get into the realm of space-based mapping. With a virtually cloud-free image of earth, Landsat gives us a georectified imagery base from which extremely precise shorelines can be extracted. And it was done! The Prototype Global Shoreline, using a carefully researched, crafted and tested digitizing algorithm created a global shoreline that can be used at between 1:125,000 to 1:62,500 scales. If DCW/ONC shorelines are moderately accurate and World Vector Shorelines are extremely accurate, Prototype Global Shorelines track the shoreline with a high degree of reliability. That is until one zooms in and studies the PGS vectors as they relate to the Landsat image from which they were derived.

EVS and PGS Vectors

Upon closer inspection, they do not track the shoreline very often. They are typically anywhere from 15-meters to 200-meters off-center. Their vectors have a habit of "stuttering" unneccessarily as can be seen in the above image. They also do not account for large sections of shoreline that is water innundated, per NIMA's request.

EVS Would Digitize the Water Inundated Areas

EVS vs PGS Precision

Finally I get to my product, Enhanced Vector Shorelines (EVS). All of my shorelines are done by hand. The vector plotting errors inherent with this methodology are minimal compared to PGS errors. EVS provides the most accuracte shorelines extracted from Landsat ETM+ 2000 mosaics. Unfortunately, that only includes the coast of Morocco, Taiwain, Madagascar, Baja California, Caspian Sea and many islands scattered throughout the world.

Now to repeat the question I posed at the beginning of this post, "Who cares?" Should the world shorelines be mapped at EVS precision? Is the PGS, which is pretty good, sufficient for most projects? Is pretty good, good enough?

I think that a world shoreline at EVS precision would be extremely useful. I believe, that properly constructed, it would become the base mapping data for military, government and private sector projects for years to come.

I know I have a large number of GIS savy readers. What do you think? Should the world be mapped at EVS precision? And if so, why? Feedback would be appreciated.

Enjoy!

Labels: DCW, digitize, EVS, Global Shorelines, Landsat, ONC, PGS, SRTM, WVS

Posted by Mr Minton at 3/11/2007 04:50:00 PM | Permalink | Comments | links to this post

For the past 3-days I've been lost in the world of DCW - Digital Chart of the World (aka VMAP). I know more about this grand mapping monument than I should ever know. It is based on ONC 1:1,000,000 scale military base maps that are based on some pretty old data (WW II and beyond). The ONCs were constructed for pilots to scan the earth as they are flying for identifiable features. ESRI took these maps, back in the early 1990s, and digitized them. From this data they created the Digital Chart of the World. Now let's fast forward to today.

I am currently teaching 6th graders about African geography. The region of Africa that is always a challenge is West Africa - Ivory Coast, Ghana, Togo and Benin. So I dutifully teach them and they dutifully learn all about African countries. In the process, curious soul that I am, I decided to study the available mapping of a small African country - Togo. One of my favorite mapping websites is Relief Web, a UN affiliated group that reports on people in need and helps to coordinate relief efforts, thus the name. They have a mapping library that is very interesting. So I wandered into their map library and snagged a few Togo country maps - one produced by the CIA (the bland one) and the other produced by the French government (the colorful one). The CIA map is a relatively old map, but the French product claims to be produced in 2006.

Curious soul that I am, I load the French map into Global Mapper, georectify it and digitize the road network for Togo. It didn't take long, maybe an hour. I imported this Togo road network into Marplot and compared it to the DCW Togo road network. You know the answer - it was the same road network, the DCW stuff.

And than it hit me. Almost every small scale base map found today still uses DCW layers of information. Some of these layers (elevation, rivers, etc.) will always be useful. Some of the layers, like roads, were poorly plotted on the ONCs originally and the same misplots are still being used today. Just overlay DCW roads on top of the appropriate Landsat ETM+ imagery and you will see DCW roads seldom, if ever, match the actual roads. Landsat ETM+ could be used to correct some of these transportation misplots, but it is tough to do at it's typical pixel resolution. The 1-meter resolution imagery is the ticket! (Are you listening Digital Globe?) I know it is being used to create up-to-date road maps in large cities, but it should be used to create the NEW and IMPROVED DCW. What a cartographic coup for the entreprenurial company (Are you listening Digital Globe?) that would sponser this effort!

And that was my tangent! What the heck am I messing around with Togo road networks and DCW when I want to make maps of islands. For 3-days I've been lost in DCW, Togo and off on a tangent. Oh, well, perhaps this evening I'll get back to my primary mission, island mapping, and leave my DCW / Togo tangent alone.

A word of warning - Tangents are alluring, but typically take you where you need not go. Stick to your target path. It's where you want to go.

Enjoy!

Labels: DCW, Digital Globe, ESRI, Global Mapper, Marplot, Relief Web, tangents, Togo

Posted by Mr Minton at 2/05/2007 05:49:00 AM | Permalink | Comments | links to this post