Thoughts - Working on the Komodo Islands EEVS Precision Island Mapping Project

Komodo Islands, Indonesia

Bima, Indonesia (txu-oclc-21752461-sc50-4) Perry-Castañeda Library
Map Collection

Why Make Another Map of a Previously Mapped Island?

The highly detailed mapping for this group of islands is paper. I create digital maps. The paper map lives in a library map drawer. My digital map will be available for any person wishing to use it. The raster imaged map above is a US 1:250,000 scale topo created from aerial surveys conducted in the 1940s and 50s. The scale my finished map will be useful is between 1:50,000 to 1:125,000. My map will contain additional layers of information detailing types of vegetation and reefs. Plus, I just like to make island maps.

Komodo Islands - EEVS Precision Digitizing using Landsat ETM+ Imagery (1:20,000)

Komodo Islands - EEVS Precision Digitizing using ASTER Imagery (1:20,000) Credit: NASA/GSFC/METI/ERSDAC/JAROS and U.S./Japan ASTER Science Team

Komodo Islands - EEVS Precision Digitizing, Size Modified (1:20,000)

Better is Better and More Accurate is More Accurate

I love the ASTER imagery for this island group. It is extremely detailed and provides a cloud-free look at almost all of the islands within this group. One is able to get an excellent view of different types of vegetation - mangroves, dense forests and scattered brush. Comparing it to the Landsat ETM+ image, the ASTER image provides a greater amount of cloud-free coverage. Combining the two images, ASTER and Landsat, one is able to create a virtually cloud-free image of the Komodo Island group. In the tropics, cloud-free is unique. One challenge was the georectifying of the ASTER image to the Landsat ETM+ image. It took 27 unique ground control points to twist, stretch and tug the ASTER image so that it precisely overlay the base Landsat image. Once that task was accomplished, I got around to digitizing layers of information. My first layer is always the island shoreline. Then comes all of the additional layers. I have completed the beaches and an inland vegetation layer at the northern end of Pulau Komodo and am currently working on the mangrove forest layer.

Pulau Siaba Besar and Kecil Islands - Landsat ETM+ Image (1:20,000)

Pulau Siaba Besar and Kecil Islands - ASTER Image (1:20,000

Pulau Siaba Besar and Kecil Islands - EEVS Precision Map, Preliminary (1:20,000)

Mapping at EEVS using ASTER Imagery

The above map is an example of the level of detail one can extract from the ASTER image. Those dark green areas along the island's shore are mangrove forests. Interestingly, these mangrove forests seem to primarily form along the eastern shores of the islands. This would be where the water is less turbulent.

Komodo Islands - Mangroves

The vegetation layer identified as EVS Vegetation Wetland, mangrove forest, detailed on the Pulau Siaba Besar map above, would look like the above image, dense dark green foliage along the shore. The dense dark green foliage that one sees inland will be classified as EVS Vegetation Forest (Hi). As you can see from the above image, much of the land is sparsely covered with vegetation. I have identified that layer as EVS Vegetation Scattered, which will include low lying grasses and small bushes.

Comparison - Landsat ETM+ to ASTER Images (1:5,000)

Pulau Siaba Kecil Island - DigitalGlobe Image from Google Earth, Size Modified (1:5,000)

Pulau Siaba Kecil Island - EEVS Precision Map, Preliminary, Size Modified (1-5,000)

Mapping at Scales Between 1:1,000 to 1:2,500 Using DigitalGlobe Imagery

In a perfect world, maps created from DigitalGlobe imagery found in Google Earth would be owned by their map maker and that map maker would be free to use that map anywhere and anytime they wished. No restrictions. No ownership delimmas. Just a map one would be free to use as one sees fit. But this world isn't perfect and DigitalGlobe and Google Earth have stern restrictions on how one is allowed to use their imagery. Pulau Siaba Kecil EEVS precision map was constructed off of DigitalGlobe imagery found in Google Earth. I am able to post my map, but there are restrictions on how I might use this map further. With that said, let's move on.

I decided to experiement using DGs hi-res imagery found in GE. I have used their mapping tools before and found them easy to use, intuitive and flexible. There are drawbacks, but one can work around them easily. The DG imagery allowed me to digitize the dense vegetation along the island's western shore. I have mixed feelings working with hi-res imagery. It is the best for extremely accurate work, but sometimes it is too much. If you aren't careful, you can find yourself digitizing the location of individual trees or offshore rocks. That is overkill for my maps.

All other mapping within the Komodo Island group will be taken from ASTER or Landsat ETM+ imagery. A variety of vegetation layers will be used, along with at least two reef layers. All of the islands are outlined and I am currently working on vegetation layers for Pulau Komodo. Wish me luck and...

Enjoy!

Musandam Peninsula OM - A Revisit of a Previous Post

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Oman - Landsat ETM+ N-40-25_2000 (1:175,000)

Musandam Peninsula - EVS Precision Map (1-175,000)

Musandam Peninsula - EVS Precision Map with 50-Meter Contour Intervals (1:175,000)

The above EVS Precision map project of the Musandam Peninsula was completed around the first week in September 2008. It was my last mapping "hurrah" before the start of this school year. I remember loving the look of this unusual piece of land calling it a "peninsula of peninulas.

Musandam Peninsula, Oman from Earth Observatory (EO)

It seems that the folks at EO dusted off a 2004 ASTER image of the Musandam Peninsula and posted it to their site today. The peninsula is still lovely to look at!

Enjoy!

The Great Blue Hole Located on Lighthouse Reef, Belize

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Lighthouse Reef and The Great Blue Hole from Advanced Land Imager (ALI) on NASA’s Earth Observing-1 Satellite

On April 3rd the above image was posted to Earth Observatory's Image of the Day. I read the article with mild interest. I was aware of the these features, cenotes, being found throughout this part of the world. After downloading the 4 MB image of the entire reef, I figured that it would be an excellent island mapping project. I checked out the Landsat ETM+ image and it is cloud free and quite detailed. So, I began to map it.

Lighthouse Reef and the Great Blue Hole - Comparison Landsat to ASTER Images

The small cays that are located on the reef at first glance looked to be fairly simple. They were not! Wanting to do justice to the details shown on the base image, my digitizing was ultimately complex. I worked at scales between 1:25,000 to 1:12,500 for most of my digitizing.

Lighthouse Reef and The Great Blue Hole, Belize - Landsat ETM+ N-16-15_2000 Image (1-220,000)

Lighthouse Reef and The Great Blue Hole, Belize - EVS Precision Map Preliminary (1-220,000)

10-days and about 20-hours later, I am done. All of the layer colors used are my usuals, except for the ocean layer. I went with a darker blue. In my opinion, the deep blue ocean color accents the many shades of blue used in detailing the reef system.

Great Blue Hole from National Geographic

If you are curious about this feature follow the links found throughout this post. Wikipedia also has an informative article about the Great Blue Hole you might find interesting.

From a mapping perspective, I am pleased with my finished product. However, to truely appreciate the amount of detail included on the map one needs to study the vector map. It is really cool! Oh, well...I'm glad it's done. Now on to the north coast of New Britian and more reefs.

Enjoy!

Kasatochi Island - Site of an August 2008 Volcanic Eruption

Kasatochi Island - Landsat Image from N-01-50_2000 (1:16,820)

Kasatochi Island - ASTER-Terra Image AST_2003273 (1:16,820)

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Kasatochi Island - EVS Precision Map (1:16,820)

I am an opportunistic island mapper. When I encounter an interesting island and it is mappable, I map it. So it goes with Kasatochi Island. Today's article in Earth Observatory Newsroom detailed the recent activities of Kasatochi Island. Located toward the western end of the Aleutians, this typically dormant volcanic island erupted on August 7, 2008. The eruption spewed out such a large amount of ash that Alaska Airlines cancelled 44 flights. The volcanic activity has continued and is being monitored daily by the Alaska Volcano Observatory (AVO). Follow the aforementioned link and it will give you all of the latest facts concerning this island's volcanic activity.

The Aster-Terra image is dated 09/23/2003, well before the current eruption. The Landsat image predates this by at least two years. I have no post eruption images, so all you get is a before map. The island is covered by vegetation, most probably low lying grasses. I am certain this eruption has refashioned the island's ground cover. At the bottom of the caldera was a small lake. It was probably vaporized in the eruption. When post eruption images become available, I will make a post eruption map to go with the above map.

Enjoy!

Jabal al-Tayr YM - One More Time

Jabal al Tayr - ASTER Image

This image is the latest post on one of my favorite websites - EO Newsroom. This site is always good for informative and interesting images, typically accompanied by well-written articles. If you've never visited, visit - it is worth the time.

I am including this ASTER image of Jabal al-Tayr. It is a closeup of the volcano that erupted September 30th. The image used in my previous post, Jabal al-Tayr YM, was extracted from a circa 2000 Landsat mosaic. This one, at 15-meter resolution, is clearer than Landsat. Fortunately, my original map is still a high quality rendering of the island shoreline and it's contours.

Enjoy!