GeoPearls - Thoughts

Yolanda, this should be Daniel's video.

Enjoy!

This is a disappearing island. It is not sinking, but sea level is rising and motus are disappearing. One estimate as to when this atoll will sink beneath the ocean surface is by 2015. As a result, the islanders are being relocated to dry land.

The Wikipedia article about Carteret Atoll is excellent in it's scope and detail. By 2007, according to the article, all inhabitants will be relocated. Due to rising seas, the island's fresh water supply is being heavily tainted with saltwater. Another article called "Carteret Islands Evacuation" includes a number of photos and an interview with inahabitants. And finally, The Guardian Unlimited, in an article entitled "Pacific Atlantis" discussed the plight of people living on low-lying islands in this age of melting ice and rising seas.

I love islands! They have an almost magical pull on my very being. This post makes me sad. I will not wade into a discussion of the reasons for this disaster. But a world without low-lying islands, without palm trees leaning from the shore to the water's edge, without beachs to explore, without the sounds of village life, without the sounds of a healthy shoreline is lessened. I don't know that they can be saved, at this point. For my part, I will continue to map them thus giving them a permanent place in our "Blue Marble" psyche.

This is not an "Enjoy!" post.

Labels: atoll, EVS, Global Mapper, global warming, island, Landsat, map, Marplot, Papua New Guinea

Eiao Island - SRTM/DEM With Contours

Eiao Island - Contours 50-Meter Intervals

This was going to be a "How To" post, but I am not ready to tell you "How To" yet. I am still figuring all of the intricacies that apply to creating contours from Global Mapper. Needless to say, it is a fairly simple process. Load the SRTM DEM/HGT file, determine contour criteria, select "Create Contours" from the File Menu and you have created a series of contours.

Obviously, the contours are only as good as the underlying data (SRTM).  As I work more with the data and how it foots with Landsat and Google Earth 1-Meter Imagery, I will gain greater confidence in creating a new layer of information to be included with some of my high islands.

I think it could be a great addition to my EVS Islands. Just have to wait and see.

Enjoy!

Labels: contours, EVS, island, map, SRTM

This post is all about EVS layers of information. You might want to pause it between slides and read my notes below the first time through. The next time, view it at a faster speed. So lets discuss the various layers used on this island.

The first 3-slides are for orientation purposes. Kaukura Atoll is located in the Tuamotus. It is a medium sized atoll.

Slide 4 - EVS Ocean Mask - I always place the atolls onto an ocean mask. Marplot has either a white or black background. Both not very practical to display an island on.

Slide 5 - EVS Shoreline - My shorelines were extracted from Landsat imagery.  This layer is one of my core layers.  It is the reason I make maps in the first place.

Slides 6 & 7 - EVS Land Island & EVS Airfield - The Land Island fills out the island giving it some land to view.  If the island I am mapping is high, often this is the only additional land layer I will include, since I do not include elevations. 

Slides 8 thru 13 - EVS Vegetation Layers - Althought the identification of vegetation from Landsat is relatively easy, to determine the density of that vegetation is difficult.  My EVS Vegetation layers are as consistently identified as I am able to visually do.  One of the difficult layers is the EVS Vegetation Wetlands.  These tend to show up as a darker shade of green on the base image.

Slides 14 & 15 - EVS Land Bare & Land Sand - These layers define vegetation free areas.  Land Bare is darker colored whereas Land Sand is most often white to shades of white.

Slides 16 thru 20 - EVS Reef Layers - The challenge with reefs is to determine depth of water based on what is visible.  The reef that is lighter in color I classify as EVS Reef Shallow.  As the color of the reef gets darker, I attempt to delineate logical divisions between various depths.  My final reef is called EVS Reef Deep which is the darkest area within the lagoon.

These are some of the decisions I have to make as I construct my maps of islands.  I strive for consistency and as clean and sharp a delineation as possible between layers.

Enjoy!

Labels: atoll, EVS, Global Mapper, island, Landsatg, map, Marplot

Lukunor Atoll FM

I've spent the morning exploring Pacific Islands using Google Earth while watching Saturday College Football. During my travels, I checked out Lukunor Atoll and noticed something that shows up all too frequently - people pollution.

Lukunor Atoll - The populated motu (1,000+)

What is that dark stuff along the lagoon shore of this motu? I think it is people residue - poop, pee and garbage. It only shows up where people live. These populated atolls aren't known for their state-of-the-art sewage facilities. Most often the poop, pee and garbage end up in the lagoon.  I can't speak for Lukunor, but the sewage and garbage most likely ends up in the lagoon. Just a guess.

Lukunor Atoll - The populated motu (1,000+) Detail

This looks like people pollution to me. Especially, when you compare this populated shoreline segment with an uninhabited motu within the same atoll.

Lukunor Atoll - Populated motu and unpopulated motu

Lukunor Atoll - Unpopulated motu and a pristine shore

This is an image of a clean shoreline.  This motu seems to be unpopulated - no people poop, pee or garbage.  This lagoon is flushed continually by the deep blue sea which gains access through some very large hoa's.  The atoll would be able to maintain a decent level of cleanliness if it weren't for the people.  We apparently generate much more pollution than the normal flushing system can handle. 

People will live on islands. They will poop, pee and generate garbage. We need to do a better job at handling the pollution we generate. I know that the issue of pollution control on small islands is one that is oft discussed, but apparently difficult to solve. I don't have a ready answer, but the damage created is visibly evident. We need to be excellent stewards of our world. It is the only one we have.

Enjoy!

Labels: Digital Globe, environment, Google Earth, island, pollution, reef

Qibla at Mecca SA - Google Earth Image

I have had a number of visitors checking out Atoll Tematangi, the supposed antipode of the Qibla at Mecca. The curious soul that I am, I performed my own calculations. The above Google Earth image is of the Qibla at Mecca. I have annotated the image with the lat-lon (21.422508 39.826138) of the Qibla.

To calculate the antipode of the Qibla at Mecca do the following: 1) switch the sign on the lat 21.422508 to -21.422508. 2) take the lon and subtract it from 180 (180 - 39.826138 = 140.173874) then switch the signs (140.173874 to -140.173874).

Antipode of Qibla at Mecca - Marplot Map

The precise antipode of the Qibla at Mecca is located, as one can see, in the middle of the deep blue sea. The nearest land is Atoll Tematangi FP. However, that island is 50-km to the SW. If one wanted to pray from the precise antipode of the Qibla at Mecca a floating vessel would be required.

If one were to position themselves anywhere on Tematangi Atoll so that they might turn in any direction to pray toward Mecca, they would be 50-kms off (+ or - 6.7-kms the radius of Tematangi Atoll). The image below shows the location of the Antipode of Tematangi Atoll. It is not Mecca, but near a reservoir outside of Jeddah.

Antipode of Tematangi Atoll - Google Earth Image

A final word - the antipode of the Qibla at Mecca is an often discussed topic on the Internet. Some who discuss it do so with disrespect. I, on the other hand, have a great deal of respect for Islam and it's practices. So, I hope this post is not offensive to those of the Islamic faith.

Enjoy!

Labels: antipode, Mecca, Tematangi Atoll

Frequent visitors know that I have a dream - to map shorelines of the world at a level of precision which I call Enhanced Vector Shorelines (EVS). Using Landsat ETM+ 2000 imagery, which I might add is the same imagery used to create the Prototype Global Shoreline (PGS), I would delineate, using vectors, all shorelines. PGS came close, but still requires a considerable amount of "fine tuning" before it would mirror EVS precision. In addition, PGS, at the request of the National Geospatial-Intelligence Agency (NGA), followed a mapping protocol that excluded water-inundated shoreline (swamps, some wetlands, etc.). Not all was excluded, but some.

My initial question - When is a Shoreline a Shoreline? - begs to be answered. Intuitively, the WVS seems to track the shoreline. It would be the shoreline that EVS would follow, after improving upon it. PGS, however, follows the inland shoreline. I guess you would call it the permanent shoreline.

If I am a sailor steering my craft into this area, I would be sad when my boat ran aground well before the PGS depicted shoreline was reached. In NGA's zeal to create a consistent shoreline I believe they left out shoreline that all of us map makers, sailors, maritime engineers and coastal commissions would require.

As I make the above statement, I am keenly aware of the nature of these water-inundated shorelines. They are highly dynamic, fluid entities that often exist fleetingly. On the other hand, if they can be imaged by Landsat, or any of the other satellite imaging concerns, they should be mapped.

Most certainly, NGA, along with MDA, have a plan of attack for these shorelines that aren't shorelines. The PGS is a "prototype" waiting to be finished. It is most probably a funding issue that once satisfied will tackle the mapping of the world's dynamic shorelines.

My EVS-approach would be to map these outer margins as shorelines during phase one. If it floats and it is attached, map it. This would include the outer limits of wetlands, mudflats, river deltas, etc.) They would be tagged as dynamic in nature, subject to change. These shorelines, once tagged, could then be monitored on a scheduled basis for any substantitive changes. When changes are detected, digital mapping would be updated. Paper maps would be updated through existing channels (Notice to Mariners, etc.) on a less frequent schedule.

So all of you "sea-faring" folks, all of you with coastal shoreline interests - When is a Shoreline a Shoreline? PGS solution or EVS solution?

Labels: EVS, map, MDA, NGA, PGS, shoreline