EVS-Islands

Cook Islands - Landsat ETM+ Coverage

I have been very busy digitizing islands. In fact, I have just completed digitizing over 3,000 large and small islands making up the western portion of the Solomon Islands. I'm currently digitizing island shorelines in Papua New Guinea. All of this work is being done at EVS precision - using Landsat ETM+ base imagery and digitizing shorelines at a scale between 1:25,000 up to 1:50,000. Some of you have reminded me that because Landsat ETM+ is typically 14.5-meter resolution that digitizing at the scale I work at is overkill. After spending close to 3-years working with 14.5-meter resolution imagery, the maps I am able to produce work quite well. I wouldn't want to sail into a lagoon using only ETM+ imagery, but I could do excellent advance planning and rough navigation using maps derived from this imagery. I know my maps are often far superior in shoreline validity when compared to some of the very old nautical charts still in use today.

Anyway, this is supposed to be about green dots on a deep black sea. In between work on the Solomons and Papua New Guinea, I completed EVS precision mapping of the Cook Islands. The first image in this post struck me. It took seven Landsat ETM+ mosaics to cover the Cook Islands. If you study the above image at full size, almost all of these very small islands are impossible to see. Yet, they enable countries, like New Zealand, to claims (EEZ) enormous chunks of liquid real estate. These very small islands play a significant role in the distribution of world resources. Interesting.

Cook Islands - Marplot Map with 25-km Ocean Masks

The Marplot map of the Cook Islands shows their distribution more clearly. They are scattered about within a peculiarly shaped border, that is if one finds rectangles peculiar. Actually, their EEZs would spill outside of their international border. I'm not sure if the border serves to limit their 200-NM EEZs. If that is the case, too bad for New Zealand and the Cook islanders.

Penrhyn Atoll CW - Landsat S-04-05_2000 Image (1:125,000)

Just to confirm that there are islands located in this broad expanse of black ocean, here is one of them, Penrhyn Atoll. It has a classic atoll shape with a lagoon full of near surface coral heads. I have not researched Penrhyn as I was in a digitizing mode when I worked on it, not in an investigative one.

Penrhyn Atoll CW - EVS Precison Island Polygon Map (1:125,000)

This is my EVS precision map of Penrhyn Atoll. It is a solid shoreline depiction. My customary mapping effort of an atoll would include a number of additional layers of information - reefs, beaches, vegetation. As my client requires only shorelines, I digitizied and mapped the island's above-water shoreline and portion of it's awash reef. Again, it is a solid shoreline mapping effort and one that I will revisit to complete the other layers of information I would typically map.

I am still here, just not able to post as often as I would like. When I finish my paying mapping project (Whoopee!), I will share many, many, many more islands. Until then...

Enjoy!

Labels: Cook Islands, digitize, EVS Precision, Landsat ETM+, Papua New Guinea, Solomon Islands

Posted by Mr Minton at 4/30/2008 08:22:00 AM | Permalink | Comments | links to this post

It has been a few days since my last post, but it has been a very busy few days. I am working on a paying island mapping project. The client ( who shall remain anonymous) wants the eastern Pacific islands mapped at EVS precision (using Landsat ETM+ as base imagery). For the past four days I've been mapping the Solomon Islands. All I have to do is create a shoreline polygon for each island. If you've ever studied the Landsat imagery for this part of the world there a lots of clouds. Clouds are a royal pain to the shoreline digitizer. However, I am an enterprising soul and am using Landsat 1990 imagery to try and skirt the cloud issue. It works! Now for the challenge associated with this project. I have 1,000s of islands to digitize, label, add elevation contours and bathymetry, create urban polygons and label, and all of this within two to four weeks. This is what I wished for and now I have it. I will work many many many hours on this project and get paid a few thousand for my efforts (it's never enough). But am I complaining. No, not at all. This is what I want to do - make EVS precision maps of islands. At the end of this project I will have completed EVS precision mapping for the eastern Pacific. That is quite an accomplishment. So my "For Hire" shingle is out. Any more takers? Enjoy!

Labels: EVS Precision, Landsat ETM+, Landsat WRS, Pacific Ocean

Posted by Mr Minton at 4/22/2008 08:48:00 AM | Permalink | Comments | links to this post

Gough Island - Landsat S-29-40_2000 (1:65,000)

Gough Island - EVS Precision Map with 50 Meter Contours (1:65,000)

Gough Island, a dependency of Saint Helena Island, is located in the distant south Atlantic. Today, South Africa maintains a weather station on the southeastern tip of the island. This is a blustery portion of the Atlantic and the island is subject to weather extremes. For more detailed information follow this link.

I actually digitized the island shoreline last summer. I wanted to fancy the map up, but had other chores to do. Now that I fancy my maps with Marplot, I finished this map tonite, April 15th - Tax Day. Taxes are a drag, but my map is nice.

Enjoy!

Labels: Atlantic, EVS Precision, Global Mapper, Landsat ETM+, Marplot

Posted by Mr Minton at 4/16/2008 12:34:00 AM | Permalink | Comments | links to this post

Lukuga River - Entire River Overview Landsat S-35-05_2000 (1:1,000,000)

I am done! To manually digitize a river is a challenge. Lots and lots of twists and turns make up the river's shoreline, as well as water-inundated areas. One frequently must decide where the river shore ends and the river begins. After one completes the river shore, then comes the islands. The Lukuga River has almost 1,000 island polygons. The majority of this polygons are very small, but the conscientious map maker digitizes every visible feature that might possible belong to a certain layer. Let's take a look at what I was able to accomplish.

Lukuga River - Entire River Overview EVS Precision Map with 100-Meter Contours (1:1,000,000)

At this scale the effort might not look very impressive. However, having digitized this east-west flowing African river and it's many islands, it is an impressive effort. I've added SRTM generated 100-meter contours. Lake Tanganyika makes up the eastern edge and the Lualaba River is the western edge. Now for a few close-ups.

Lualaba and Lukuga Confluence - Landsat S-35-05_2000 (1:50,000)

Lualaba and Lukuga Confluence - 3D View Landsat S-35-05_2000 (1:50,000)

Lualaba and Lukuga Confluence - EVS Precision Map (1:50,000)

This series of images show the confluence of these two rivers. The Lukuga has meandered over relatively flat westward sloping terrain for about 200 kilometers before joining the Lualaba. The large island at the western end of the Lukuga is a water inundated feature that was a challenge to digitize. Water and land quite often blend making digitizing difficult.

Lake Tanganyika and Lukuga Confluence - 3D View Landsat S-35-05_2000 (1:250,000)

Lake Tanganyika and Lukuga Confluence - EVS Precision Map with100-Meter Contours (1:250,000)

These images show the Lukuga flowing from Lake Tanganyika through the town of Kemba. The Landsat image shows agricultural lands throughout this area. The river then courses through a cleft between the hills to the west.

I'm going to go ahead and post this. I have one more series of images to include, but I'll add them when I return after a date with my wife. I hope you all find this effort interesting. I, myself, find it extremely satisfying. This river is mapped at EVS precision, manual digitizing from Landsat ETM+ 14.5-meter resolution base imagery.

Enjoy!

Labels: EVS Precision, Global Mapper, Landsat ETM+, Lualaba River, Lukuga River, riverine islands

Posted by Mr Minton at 4/13/2008 12:12:00 PM | Permalink | Comments | links to this post

Bastoy Island - Landsat ETM+ Image N-32-55_2000 (1-20,000)

Bastoy Island - EVS Precision Map (1-20,000)

When I was a young man I learned a language that used to be widely practiced. Now it is an oddity employed by radio amateurs. Morse code was once the primary method of communication within many sectors of the world of the 1960's and 70's. I encountered it in the military. I still enjoy hearing the "dits" and "dahs".

This island is home for Norway's privledged prisoners. Apparently, Bastoy Island is a minimum security prison that is a choice location for all convicted Norwegian criminals. Not only prisoners visit this island, but radio amateurs as well.

Bastoy Island will be the location that LA4HNA and friends will transmit from between June 20-22, 2008. He will not transmit in CW (morse code), but will use RTTY and SSB. Oh, well, that's ok. I like RSGBIOTA (Radio Society of Great Britain Islands On The Air). They encourage amateur radio transmissions from islands around the world - a real natural for me.

Someone that looked at LA1NIS's website visited EVS Islands, perhaps looking for a map of Bastoy Island. If they wanted one, now they have it. The map took about 2-hours to complete. The best resolution imagery is Landsat ETM+. However, Statens Kartverks has excellent, highly detailed mapping for all of Norway. I used their mapping to digitize the road network on the island.

. -. .--- --- -.--!

Labels: EVS Precision, LA1NIS, Landsat ETM+, Norway, Staten Krartverks

Posted by Mr Minton at 4/05/2008 08:18:00 PM | Permalink | Comments | links to this post

When I was in 5th grade (10-years old), I told my folks that as soon as school finished, I planned to leave home and do a "Huckleberry Finn" along the Missouri and Mississippi Rivers. I would construct a raft and float along at a carefree pace. I yearned for that freedom, that independence. Needless to say, I didn't make the raft trip, but a long voyage into uncharted, unexplored waters still holds a fascination for me.

Lukuga River (280-km) - Landsat S-35-05 (1-1,500,000)

The Dark Heart of Africa, the Congo River basin is an expansive, sparsely traveled hydrological highway encompassing the center of Africa. To the west is the Atlantic coast and to the east is the Rift Valley lakes. What a place to explore!

The above image is centered on the Lukuga River, the only major outlet for Lake Tanganyika. It connects to the Lualaba River, which flows into the Congo River. 3067-kilometers later, one would arrive along the Atlantic coast of Africa. What a magnificent journey it would be! The trip of a lifetime.

Lukuga River - Landsat S-35-05 (1-25,000)

My mapping of the Lukuga River, is progressing. I have completed 60% of the river shorelines. The additional 40% of shoreline will be completed before the weekend. Then I will work on the many riverine islands that are found within the river.

Congo River Journey (3067 km) - Lukuga, Lualaba and Congo (1-7,700,000)

Picture yourself in a kayak plenty of supplies and with the assurance you will always have access to necessary supplies. Each day the beauty and magnificence of tropical Africa would be yours to explore.

Unfortunately, this part of Africa is in dramatic turmoil. It is the playground of thugs, killers and miguided fighters that believe a well-aimed bullet solves local, regional, national and multinational problems. Problems that the dead and dying will never solve. An intrepid river explorer would be well-advised to avoid exploring this stretch of river without local guides that have well-established connections with all warring factions. Even then, the trip would be extremely dangerous.

Now let's dream. Image exploring this river system without the fear of death from bullets or machetes. Where the only challenges facing you would be those presented by the rivers, not the people living along the rivers. Maybe a 10-year old kid could seriously dream of exploring these rivers that make up the heart of Africa.

Enjoy!

Labels: Africa, Congo River, Landsat ETM+, Lualaba River, Lukuga River

Posted by Mr Minton at 4/02/2008 05:06:00 PM | Permalink | Comments | links to this post

Kingman Reef - Landsat Image N-03-15_2000 (1-75,000)

Things can heat up at EVS Islands pretty fast, especially when National Geographic requests information about one of my mapping projects. Respected group that they are, they constantly research many areas prior to selecting a few primary areas for more thorough studies. One such area they are studying in depth is Kingman Reef. Since I have done mapping of the reef, one of their mapping team members contacted me and asked about my map of the reef. Needless to say, I was quite excited, yet apprehensive. I knew that the Landsat ETM+ imagery for this reef was not the most revealing. I remembered that in order to construct my EVS precision map I had to "trick" the image.

Kingman Reef - "Tricked" Landsat Image Over EVS Precision Marplot Map (1-75,000)

Using a Blend mode in Global Mapper that made the black colored sea transparent, the reef appeared as a murky yellow smudge. Using this yellow smudge to define the limits of the reef, I mapped it. Comparing my map to a nautical chart of the area, it turns out my EVS precision map of Kingman Reef is a solid effort. After numerous emails back and forth, I sent NGS my Kingman Reef vector files and various images to help them in their study of this reef.

Kingman Reef 10007409B01

Kingman Reef 10007409B01

Kingman Reef - Combined Image (10007318D01 and 10007409B01)

Let's talk about a "perfect world" where we all have access to the best imagery. I should have used DigitalGlobe's exquisite imagery of Kingman Reef to construct my map. A quick scan of DigitalGlobe's available imagery covering Kingman Reef reveals two nearly cloud-free views of the reef. An equally quick "cut and paste" gives me a revealing view of the reef. I could have made the ultimate map for this reef using these two images.

Let's do a "what if". What if my original Kingman Reef project had been constructed from these two DigitalGlobe images? What if I could have told the NGS rep that they were getting the best map availabe for this particular reef, because it was constructed from the best available imagery? What if I could have emailed them a copy of DigitalGlobe's imagery and my vector files for Kingman Reef? What if they would use and credit DigitalGlobe's imagery and my map of Kingman Reef in a future article? I think that is called "win-win".

And let's end this post with a proposition - DigitalGlobe, what would it take for you to make EVS Islands your island imagery charity case? Do you need me to be a non-profit? That is what I intend to do with EVS Islands. If you give me access to your island image archives, I promise I will make the best island maps possible. Using your imagery, I will teach young people the fine art of map making. I promise not to get in the way of your ongoing operations. I will quietly access island images from your archive, construct island mosaics and continue to make the best island maps possible.

Come on, DigitalGlobe, let's make a deal!

Labels: DigitalGlobe, EVS Precision, Kingman Reef, Landsat ETM+

Posted by Mr Minton at 2/25/2008 02:15:00 PM | Permalink | Comments | links to this post

Bikini Atoll - LIIM N-58-10 (1:200,000)

I decided to digitize this atoll because the Landsat Island Image Mosaic is cloud-free and it has a certain amount of notiriety connected with nuclear weapons testing and population displacement. As a youngster, I watched rebroadcasts of one of the blasts on TV. It was probably the Bravo blast, the one that left the big hole in the northwest portion of the reef.

The islanders are still displaced. It seems they tried to reestablish themselves back in the 70's. After awhile they were beginning to glow (figuratively speaking). They were taken off of their home and scattered onto other islands. Now, tourists are allowed to visit, along with divers and fishermen. The island and it's waters have been deemed safe for short stays. Just don't drink the groundwater, eat the coconuts, land crabs or fish. One advantage if you stay for a long time - you won't need a lantern at night, your radioactive glow will provide sufficient illumination. Just a joke. I know that folks earning their livelihood from tourists, divers and fishermen will resent my "glow" remarks. I apologize to them. But, the U.S. military screwed up when they blasted holes in this atoll. 60-years later, I still say, "Shame on you."

Bikini Atoll - EVS Precision Map (1:200,000)

Enough about my personal gripes. The EVS precision map of Bikini Atoll was a fairly fast project to complete. The digitizing took 8-hours over a period of 2 days. The map assembly and posting has taken another 2-hours. 10-hours from start to finish for an island of this size is good. The reef, thank goodness, was relatively simple to digitize. Some reefs are quite complex and require many layers of information. This reef consists primarily of three layers - EVS Reef Shallow, EVS Reef Middle and EVS Reef Deep. They are distinguished by their respective shades of blue. The majority of the lagoon is classified as EVS Reef Deep. I used only a single vegetation layer, EVS Vegetation Mixed (Hi-Lo). I use this classification on most Landsat imaged islands with a mixture of palms and other trees along with shrubs and low-lying plants. When I am able to study a DigitalGlobe hi-res image along with the Landsat, I am able to make better vegetation layer classifications.

I still have work remaining on this project - EVS Reef Awash where visible waves appear along the outer reef and confirmation of individual motu names When I am satisfied with the outcome, I will repost the map. Until then...

Enjoy!

Labels: DigitalGlobe, EVS Precision, Global Mapper, Landsat ETM+, LIIM

Posted by Mr Minton at 2/05/2008 04:26:00 PM | Permalink | Comments | links to this post

I most often digitize from LIIMs using Global Mappers's Blend Mode called No Blend (Slide 1). No Blend shows the various land and water features as Landsat ETM+ mosaics intended them to look - somewhat natural. For most projects, this image works fine. However, atolls present some unique challenges - What is above water and what is below? What is shore vegetation and what is bare earth that looks like shore vegetation? Where does the land end and the reef begin? Like I said, unique challenges.

When I encounter these challenges, I use a couple of different options - 1) changing the background color to either Yellow (R-157,G-191,B-202), Pink (R-255,G-128,B-192), Light Pink (R-255,G-193,B-224) and Blue (R-157,G-191,B-202) and using two new Blend Modes - Difference and Color Burn. Let's talk about Difference first.

Tauere Atoll - Blend Mode Difference and Blue Background

Difference creates a soft looking false color image that makes certain atoll features stand out, for example the sand. It is also a great way to distinguish underwater features. I always switch between No Blend and Difference to visually confirm my work.

Tauere Atoll - Blend Mode Color Burn and Blue Background

Color Burn creates a sharp separation using false colors. The blue background and Color Burn allows for some potentially very precise digitizing of various island features. Using the other background colors, other than blue, gives a washed out effect. Not very handy for digitizing work.

My biggest challenge when working on an island mapping project is determining the shoreline - where the water meets the mostly dry land. Using the Global Mapper's Blend Mode and changing background colors is a great way to meet this challenge.

Enjoy!

Labels: Blend Option, Color Burn, Difference, digitizing, Global Mapper, Landsat ETM+

Posted by Mr Minton at 1/25/2008 03:50:00 PM | Permalink | Comments | links to this post

Nisos Skiathos - LIIM from N-34-35_2000 (1:70,000)

Nisos Skiathos is the westernmost island of the Sporades. It is reported to be heavily forested with pine trees. However the ugly red splotch in the center of the LIIM is a burn signature. When a forest fire occurs on a small island, it puts all of the inhabitants at risk. This fire was restricted to the mountainous interior. It would have occured over 7+ years ago and I am confident organic ground cover has returned to the area. According to a Nisos Skiathos web site, the island is heavily populated with tourists during the summer months. They visit the old fortress at Kastro (NE), long stretches of sandy beaches and enjoy a festive nightlife in Skiathos town.

My perfect visit to this island would be off-season. I would spend my time exploring and visiting with the local folks. In the evening I would walk in the town looking at the shops and selecting a taverna to dine in. Then I would retire to my room overlooking the sea. I would relax on my balcony with a good book, a glass of 20-year old port wine, a Cuban cigar and soft music in the background. I would fall asleep at 1:00 AM, wake up at 5:30 AM and start all over again. Wow! Now that is living on the edge.

Nisos Skiathos - EVS Precision Marplot Map (1:70,000)

The map was created in approximately 4-hours. It was a fairly straight forward island mapping project. Nothing out of the ordinary. I am working on color schemes for my various map layers. The colors are still being explored. I have been using Marplot's text feature. One has the option of using five different fonts. You control the size of the text by selecting and dragging it until you are satisfied with the size. I have used Time New Roman font for this island mapping project.

Enjoy!

Labels: EVS Precision, Global Mapper, Greece, Landsat ETM+, LIIM, Marplot

Posted by Mr Minton at 1/16/2008 05:54:00 AM | Permalink | Comments | links to this post

Nisos Skopelos - LIIM From N-34-35_2000 (1:100,000)

Nisos Skopelos is a fertile and densely-wooded island. Adjacent to the town of Skopelos is a harbor that handles the ferry boat traffic - tourists and goods from the mainland. There are a few smaller harbors that provide safe haven for the sailing crowd, especially the harbor at Ormos Glossa.

Nisos Skopelos - EVS Precision Map with Roads (1:100,000)

This island project took about 6-hours to complete. The shoreline was completed quickly. The feature that took the greatest amount of time was the island's intricate road network. I used a map found on Skopelos Web Site. I georeferenced the map and placed it on top of my base image. I then carefully digitized the road network, paying special attention to the size classification of the roads. I imported the completed files into Marplot where I finished this map. The names and locations of various island features were taken from Sailing Directions Pub 132, Section 16-10.

I have secured approval to use the road network on this map from the copyright owner, Yiannis Chatzitrakosas. Landsat ETM+ does a poor job of showing roads and trails, where as Yiannis' map shows all class of roads on the island..

Enjoy!

Labels: EVS Precision, Global Mapper, Greece, Landsat ETM+, Marplot, Sailing Directions, Sporades

Posted by Mr Minton at 1/15/2008 08:20:00 PM | Permalink | Comments | links to this post

Nisida Ioura - LIIM From N-34-35_2000 (1:65,000)

So you've always wanted to hand-digitize an island shoreline. Your GIS friends tell you "No way! It takes way too long. And it's not as accurate as some of these slick black-box vectorizing software packages." You ignore them. Good for you!

First get you a good software package to digitize from. You all know where I stand - Global Mapper. You can always download and try their software for free. Just select my Global Mapper sidebar link and follow the instructions. Once you've got the mapping software loaded, it is time to get your base imagery. You can either download it from the NASA site or get in touch with me and I'll hook you up with imagery for your island.

Nisida Ioura - EVS Precision and GSHHS WVS (1:65,000)

Load the imagery into GM, zoom into a section of the shoreline where you will begin digitizing at a scale of 1:12,500, switch on Anti-Alias option in the Control Panel for your base image, select the digitizing tool, select the "Draw a Line" option and start digitizing. I like digitizing to music. This morning it was "The Planets" by Gustav Holst. I traced the above island's shoreline, listened to music and sipped a cup of coffee. I started at 5:50AM and finished Nisida Ioura's shoreline at 6:05AM - 15-minutes to digitize a perimeter of 30-kilometers - 2-kilometers per minute.

I always experience a satisfying sense of accomplishment when I complete an island's shoreline at EVS precision. I know that my island shorelines are as accurate as one can get using the tools I use. I have done enough comparisons to know that my shorelines can be used to create useful maps suitable for a wide range of activities.

If you want to make your own maps, just do it. Stop making excuses. Stop letting others tell you what you can or can't do. Go ahead and make your map. If your first one looks crappy, I promise your next one will look less crappy. And after a few years of making your own maps - you'll be able to say "Now, that's a nice map!"

Enjoy!

Labels: digitizing, EVS Precision, GSHHS, Landsat ETM+, WVS

Posted by Mr Minton at 1/14/2008 09:55:00 AM | Permalink | Comments | links to this post

Isla Pinta - Landsat N-15-00_2000 (1:90,000)

Isla Pinta - EVS Precision Marplot (1:90,000)

This project took about 4-hours to digitize. The shoreline is a composite of two images. The majority of the shoreline was taken from Landsat ETM+ imagery. When it is cloud free, this imagery is easy to work with. However, when you have cloud obscured shorelines, they are often impossible to discern. The second image used is DigitalGlobe imagery taken from Google Earth. This allowed me to digitize the eastern shore.

I have included four additional layers of information, besides the shoreline - a Vegetation Sparse layer, Land Bare, Land Lava and Land Rocky Shore. All of these layers were taken from the Landsat ETM+ image.

Isla Pinta - DigitalGlobe Image from Google Earth - Eastern Shore (Red Polyline)

I love DigitalGlobe imagery! It is the best to work with, but there are so many real and possible restrictions that apply to derivitive works, maps in particular, that it is more trouble than it is worth. The red polyline is what I digitized from the DG image. I imported it into Global Mapper and stitched it into my EVS precision shoreline.

Isla Pinta - EVS Precision Marplot with 50-meter Contours (1:90,000)

Isla Pinta - EVS Precision Marplot with 50-meter Contours 3D View (1:90,000)

I took my completed map image and georectified it on top of my Global Mapper data. I also added the SRTM data to create contours and explore 3D views of the island. The first map above has 50-meter contours. The second image is a 3D view of the island looking toward the NE.

Lonesome George at the Charles Darwin Research Station (Credit: Credit: Alison Llerena/CDRS)

And finally, here is Lonesome George. He is the last Pinta Island tortise. He was found in 1972 and removed to Santa Cruz Island. He has a couple of Wolf Island female tortises as his potential mates. So far Lonesome George continues to play hard to get. He is estimated to be between 80 to 90 years old. If he doesn't hook up with a female tortise soon his Pinta Island breed ends. I wish him well and his future mate many tortise children.

Enjoy!

Labels: DigitalGlobe, Ecuador, EVS Precision, Galapagos Islands, Google Earth, Landsat ETM+

Posted by Mr Minton at 1/04/2008 07:42:00 AM | Permalink | Comments | links to this post

Tuamotu Atoll LIIMs

List of Tuamotu Atoll LIIMs

What is a LIIM? It is an island image extracted from Landsat ETM+ imagery - Landsat Island Image Mosaic - LIIM. I have just completed LIIMs for the Tuamotu Atolls. These low-lying atolls are northeast of Tahiti and southwest of the Marquesas. I have created a total of 78 LIIMs - one for each atoll. They range in size (MBs) from Rangiroa Atoll at 28.7MBs to some of the small atolls under 1MB. As I did with the Greek and Turkish islands, each zipped file contains a JPG image and two georectifying files, they are 14.5 meters per pixel resolution and 300 DPI. I did not save them with DEM files as most of them are very low lying islands. All files are UTM projection with WGS-84 datum. A handful of the LIIMs have cloud-obscured areas, but overall the images are quite clear.

Before DigitalGlobe imagery in Google Earth, I did all of my island mapping with Landsat imagery. I would love to continue using DigitalGlobe imagery, but I feel the copyright restrictions are too cumbersome to deal with. Using Landsat imagery, one can map to their heart's content. One could even make money off of their mapping. Wouldn't that be a kick?

The same offer I made with my Greek and Turkish LIIMs applies to the Tuamotu Atoll LIIMs - drop me a line if you would like to try one of these out. I will email a link where you can download the appropriate LIIM. All I ask is that you give me some feedback as to their usefulness and ease of use. So, if you would like to try one of the Tuamotu Atoll LIIMs, drop me a line.

Enjoy!

Labels: DigitalGlobe, French Polynesia, Google Earth, Landsat ETM+, LIIM, Tuamotus

Posted by Mr Minton at 1/02/2008 11:25:00 PM | Permalink | Comments | links to this post

Three Vector Shoreline's Compared - WVS, SWBD and EVS Precision

One of my readers suggested I evaluate SWBD shorelines in comparison to other freely available shorelines. Previously, I compared these shorelines with my own EVS precision shoreline. I'll do it once more.

The WVS is widely available and manageable in size. There is another popular version of it called the GSHHS. It repairs varous WVS anamolies. In addition, it conveniently breaks the dataset into land, lakes, ponds and islands. At only 56MBs zipped, it is a very attractive option. As one can see in the two images, the WVS is the least precise of all large scale global shorelines. It is designed to be used at scales of 1:250,000 and above. For most of us designing projects for our classroom, employers or customers, this dataset does a fine job, it is free and the size is reasonable. It is when we need to do large scale precise shorelines that we require the next best global shorelines

Although the SWBD is a quality product and provides the end-user with precise SRTM water-defined shorelines, it tracks the water. The SWBD attempts to identify the place where the water meets the shore. That should be the shoreline, but it isn't. The top image shows the SWBD shoreline tracking the reef edges and ignoring the numerous motus within the reef. For us island mappers, the SWBD is not precise enough to identify the many shoreline features we require.

The same can be said for the NGA PGS shorelines. They are extremely precise, using Landsat ETM+ imagery as their base imagery. This is the same imagery I use to construct my EVS precision maps. I have the NGA PGS shoreline loaded into Marplot, a mapping package I use. The dataset is divided into 24 separate groups. My global coverage, using this dataset, is outstanding - except where clouds or other atmospherics obscure the shoreline or the shoreline consists of water-inundated areas (marsh, swamp, mudflats), which the NGA PGS product didn't identify. The cloud obscured areas on Landsat ETM+ imagery are validly poorly mappable to unmappable. The water-inundated areas are mappable, but the NGA contract called for the exclusion of these shoreline features, thus they were not mapped. I beg to differ. This is shoreline that must be mapped. There are massive river deltas NGA PGS mapped that depict shorelines that look nothing like the original Landsat ETM+ image, which is full of features that the NGA PGS product did not map. They just happen to be water-inundated. They are features you and I would describe as shoreline. Make no mistake, when the shoreline is cloud-free and not water-inundated, which most Landsat imaged shorelines are, this global shoreline dataset is outstanding. It's just all of those river delta islands that they didn't map that I have a problem with.

Four Vector Shoreline's Compared

However, my EVS precision shorelines are pretty outstanding as well. When one compares my hand-drawn shorelines to programmed color tracking shorelines (or many other automated processes), my hand-drawn shorelines track quite precisely. Something about using one's brain processing powers, manual dexterity and years of experience that consistently allows one to create more precise shorelines than the WVS, SWBD and NGA PGS products.

As I work with Landsat ETM+ imagery and learn more about the digitizing craft, I am certain software is available that could do what I do more accurately, faster and in much less time. But it wouldn't be as much fun! Would it?

Enjoy!

Labels: EVS, GSHHS, Landsat ETM+, NGA PGS, SRTM, SWBD, WVS

Posted by Mr Minton at 12/31/2007 09:30:00 AM | Permalink | Comments | links to this post

59 Greek and Turkish Island LIIMs

Like I said in my previous post, I wanted to complete the primary Landsat Island Image Mosaics (LIIM) for the Greek and Turkish islands located in the Aegean Sea before I returned to school. Well, I'm done. The largest LIIM, at 100MBs, is the 3-sections (West, Central and East) covering Crete. All of the large Greek and Turkish islands located in the Aegean Sea are now covered by a LIIM. What does this mean to you?

Not much, if you have your own collection of Landsat ETM+ mosaics. Or, you are a user of Google Earth or World Wind and you say, "I have all of the imagery. What do I need with LIIMs?

I make maps using Landsat ETM+ imagery as my base image. Using Global Mapper's digitizing tools, I am able to create complex vector layers of information. I've used the digitizing tools found in Google Earth. They are good, but not great. And if you make a series of polygons, you must create a unique record for each polygon. Not practical when you create hundreds of polygons on a single map.

I need some of you to try the LIIMs out. Give me the name of a Greek or Turkish island and I'll send you a copy of the appropriate LIIM. Let me know what you think? Is it useful?

Enjoy!

Labels: Global Mapper, Greece, Landsat ETM+, LIIM, Turkey

Posted by Mr Minton at 12/29/2007 08:55:00 PM | Permalink | Comments | links to this post

I have over 600+ Landsat ETM+ Orthorectified Mosaics that two summers ago I patiently downloaded and copied onto a series of DVDs. These mosaics cover all of the shorelines and oceanic islands throughout the world. It is an impressive collection. This collection, coupled with Global Mapper v9.01 (GM), allows me to load and view the individual mosaics as I desire. Each mosaic, even compressed in MrSID format, is typically 100 to 250MBs. Them is some big files!

Over a year ago I had a discussion with a reader who wished to work with these files to make his own maps. I described where he could download the files. But, alas, he said the files, even in MrSID format, were too large for his system. Was there a smaller file of just individual islands, he asked. Not to my knowledge, I guessed and went back to making maps of islands.

That was until this past month and my work in image mosaics. First I worked with DigitalGlobe imagery. Sadly, they have never responded to my product idea. Oh, well, so goes life. Lately, I've been working with Landsat ETM+ again. And the following is my latest idea - Landsat Island Image Mosaic or LIIM.

Greek and Turkish Islands - Landsat ETM+ Mosaics

Some of my earliest mapping efforts were of Greek and Turkish islands located in the Aegean Sea. This area is virtually cloud-free and the clarity is outstanding. However, it takes seven Landsat mosaics to cover the area. Using a raster export feature within GM, I experimented with various raster formats and came up with georeferenced JPG. Pixel size of each resulting LIIM is 14.5-meters, 300 DPIs and projection is Mercator. The resulting image is outstanding.

Nisos Limnos - Landsat ETM+ N-35-35_2000

I zoomed into my target area encompassing the primary island and created the georectified JPG. The above Nisos Limnos LIIM taken from GM gives the user the complete resolution power of Landsat ETM+ without the size problems. The above file, along with it's accompanying DEM, is only 7.2MBs.

Greek and Turkish Islands - SRTM Tiles

To really bring the Nisos Limnos LIIM to life, the SRTM data is the ticket. To cover the Aegean Sea one needs 83 individual SRTM tiles. Loads of data for most of us. Many of these tiles require some fixing, which is done using SRTM Fill (freeware) to fill holes. Once this data is loaded, GM allows for DEM creation. One is able to take the Nisos Limnos DEM and drape the Nisos Limnos LIIM on top and get a variety of 3D views of the island.

Nisos Limnos - SRTM N039E025

So I exported the underlying area into DEM format. This allows for some nifty looks at the island

Nisos Limnos - 3D View

Pretty cool! This is the Nisos Limnos LIIM draped over the Nisos Limnos DEM. All of this wrapped up in a 7.2MB package. I like it. How about you?

I should add that I have created 16 Greek and Turkish Island LIIMs. The following islands have LIIMs - Bozcaada, Gokceada, Nisida Fournoi, Nisida Gioura, Nisos Agios Efstratios, Nisos Alonnisos, Nisos Chios, Nisos Ikaria, Nisos Lesbos, Nisos Limnos, Nisos Pelagos, Nisos Samothraki, Nisos Skiathos, Nisos Skopetos, Nisos Skyros and Nisos Thasos. I intend to complete coverage of the islands of the Aegean before I head back to school on Jan 03, 2008.

Enjoy!

Labels: DigitalGlobe, Global Mapper, Landsat ETM+, LIIM, Limnos Island, SRTM

Posted by Mr Minton at 12/26/2007 09:04:00 PM | Permalink | Comments | links to this post

Tsu-Shima - Landsat from USGS WRS - Original Image (1:500,000)

I did my "load and explore" exercise, where I take a random Landsat ETM+ mosaic, load it and see what looks interesting. Fortunately, I traveled to a part of the world I studied while in college, Japan. Although I speak some Mandarin Chinese and very little Japanese, my emphasis within my Asian Studies major was Japan. The islands making up Tsu-Shima rest between Japan and Korea. Both Korea and Japan claim ownership, but it appears Japan has "squatters rights" to the islands. The islands have a long history of human occupation, but the current human footprint is relatively small - over 85% of all of the islands land area is in a natural state.

So, why not transform the black and white Landsat WRS image into a useful colorized image. I decided to give it a try.

Tsu-Shima - Landsat from USGS WRS - Creating a Single Color Sea Mask - First Pass (1:500,000)

Tsu-Shima - Landsat from USGS WRS - Sea Mask as a Single Color (1:500,000)

My first task was to isolate the land area making up Tsu-Shima islands. I did this using a feature within Global Mapper v9.0 that allows you to isolate certain colors and to make them transparent. One merely identifies a RGB (i.,e., 010,215,215) color and turns it off. The first image in the two above shows a first pass. It took seven passes to convert the sea mask into a single color. Each pass required that I save the modified raster image as a TIFF file. After a number of passes, I ended up with the second image. The cloud-like features in the lower portion of the image are clouds. They were dealt with later.

Tsu-Shima - Landsat N-52-30_2000 (1-500,000)

The Landsat ETM+ image taken from N-52-30, has way too much black and the shoreline is tough to clearly makeout. I am certain others could easily determine shorelines with a smart routine that identifies shoreline colors, but I don't have this level of expertise or the software. So, I forged ahead in my pedestrian manner. Taking the above Landsat ETM+ image, which is georectified, I overlaid my modified Tsu-Shima Landsat WRS image on top of it. Again, using a Global Mapper v9.0 feature, I made the top image (Landsat WRS) 60% transparent, allowing the green vegetation layer to appear to drape onto the top image.

Tsu-Shima - Landsat from USGS WRS - Land Mask Colored (1-500,000)

I saved the resulting image, moved it into ImageForge, my "poor man's Photoshop", and touched it up. I made the sea mask a single blue color and the urban areas were changed to a gold color. I saved the modified image. I loaded this final Tsu-Shima image into Global Mapper, where it was georectified. Tsu-Shima image is good to use between 1:500,000 to 1:62,500. Anything larger and the shorelines are a series of clunky pixel shapes.

Tsu-Shima - From Landsat WRS to Landsat Modified - Central Detail

From a black and white Landsat WRS to my Landsat modified image took 4-hours to complete. I have a series of georectified TIFF image of the islands. As with all of my previous projects, they are available at no charge. Just drop me a line and let me know what you need. I like the look of my Landsat modified image of Tsu-Shima. Don't you?

Enjoy!

Labels: Global Mapper, ImageForge, Landsat ETM+, Landsat WRS

Posted by Mr Minton at 12/20/2007 11:47:00 AM | Permalink | Comments | links to this post

Lake Tana - Landsat N-37-10_2000 (1:500,000)

Lake Tana - EVS Precision Marplot Map (1:500,000)

At times I like to open a Landsat ETM+ of a region of the world and explore. This time I traveled to Africa, specifically to Ethiopia. I know the country of Ethiopia is perched on highlands and Lake Tana is the primary source of the Blue Nile. I also have read the story of the Ark of the Covenant being spirited away from Israel first to upper Egypt at Elephantine Island, then to Tana Island and finally to St Mary of Zion Church in Axum. My curiosity about Tana Island got the best of me. My first task was to research to see if any maps of the island were available via the Internet. Nothing! Not even of the lake!

So my first task was to rectify the mapping of Lake Tana. The only mapping I have depicting this lake are at a scale of 1:1,000,000 (DCW). The shorelines are very coarse approximations of the Landsat imaged shorelines as depicted on N-37-10_2000. I have spent the last 6-hours mapping the shoreline of this lake. I worked at a scale of 1:31,250 for all mapped shorelines. Smaller islands in the lake were mapped at an even larger scale. The lake's shorelines were easy to discern and digitizing was uneventful, but tedious.

Nargadaga Deset - Landsat N-37-10_2000 (1:62,500)

Nargadaga Deset - EVS Precision Marplot Map (1-62,500)

This is the largest island within the lake and the largest island in Ethiopia. I carefully digitized it's shorelines, figuring the largest island had to be Tana Island. That is until I finished and began working in Marplot. It is there that I have my EVS Island name file (86,000+ named islands). It turns out bigger is just bigger. It is not Tana Island but Nargadaga Deset. Although it is a holy island, it wasn't the holy island I wanted.

After a little searching I found Tana Island located along the eastern shore of the lake. Not a large island, but at one time, the reputed resting place of the Ark of the Covenant.

Tana Island - Landsat N-37-10_2000 (1:31,250)

Tana Island - EVS Precision Marplot Map (1:31,250)

Here is Tana Island, all of 500-meters by 50-meters. It is a holy island, with a monastery located on it. No woment are allowed to visit the island. The priest living on the island will show any men visitors where the Ark was kept while on the island.

This was a fun mapping project. I got to map a number of islands at EVS precision. I went back to my mapping roots using Landsat ETM+ as my base imagery and didn't have to worry about offending any image owners and I mapped a major lake to boot! Now, that's living the high life.

Enjoy!

Labels: Ethiopia, EVS, Landsat ETM+, Marplot, Tana Island

Posted by Mr Minton at 12/17/2007 12:26:00 AM | Permalink | Comments | links to this post

My previous post elicited a question asking which image was georectified properly and wondering if I had verified the projection. I am a trusting soul and if, in the instance of my previous post, the NGA PGS vector coordinates are what I used to georectify the ISS image. I am reasonably confident the ISS image fit precisely into the NGA PGS vectors. Ultimately the ISS image I fashioned used a Geographic (latitude/longitude) projection with WGS-84 datum.

This evening I loaded the Landsat ETM+ orthorectified mosaic N-20-10_2000, which includes Isla Blanquilla, into Global Mapper. It loaded quickly. I zoomed into Isla Blanquilla at a scale of 1:62,5000, which was the scale of my final map project. I then loaded the ISS georectified base image of Isla Blanquilla on top of the Landsat image. It is right on! A precise fit. However, yesterday when I attempted to create an overlay of the ISS image in Google Earth and after spending 15-minutes stretching and twisting the image, it never quite fit. It was alway alittle off.

Google Earth to Landsat ETM+ Georectification Offset

This evening, I recorded the lat/lon location of three relative ground control points within Google Earth and in Global Mapper's Landsat display. They each showed the same image of Isla Blanquilla and supposedly at the same location. Each relative ground control point was easily discernible. After recording lat/lons for each point and determining the difference, it seems someone is off anywhere between 2-meters and up to 63-meters for this single island. So, who is it? Who has misplotted this island? Is it Google Earth or Landsat ETM+? Care to guess?

Enjoy!

Labels: georectify, Google Earth, ISS Image, Landsat ETM+

Posted by Mr Minton at 11/30/2007 09:19:00 PM | Permalink | Comments | links to this post