EVS-Islands

***First off, most of these images come from MS Windows Live Local (WLL) and Getmapping plc.  If I am in violation of any copyright infringement issue, I will swiftly rectify the problem by removing the images.  By the way, my maps are not intended for commercial purposes.  I just like to make maps.***

With that said, let's get started!

Some months back I posted a Landsat image and EVS map of Caldey Island UK.  I felt the digitizing was as good as I could extract from the Landsat image.  That is until I checked out WLL's image of the island.  More specifically, the Getmapping plc image of the island.  It has to be 1-meter resolution or better.  The imagery is exquisite.  Just the kind of imagery that would tempt me to redigitize a shoreline and enhance a map.  So I did.

Let's begin with my original Landsat image.

Landsat ETM+ 2000 Imagery of Caldey Island (N-30-50_2000)

Not bad, actually it is very good resolution.  It is cloud-free and the shoreline is clearly discernible.  It is a good image from which I am able to create an EVS precision shoreline.  Of course there is better resolution, but it is not readily available.  That is, not until WLL and Getmapping plc teamed up.

WLL Imagery of Caldey Island

Now this is high resolution imagery.  I looked at the tools available in WLL and sure enough the program has a path creation tool.  Actually, it is more like a path drawing tool that pales in comparison to Google Earth's (GE) path tool.  Whereas GE's path tool records vertices as lat/lons, the WLL tool doesn't.  At least, I couldn't easily figure it out.  GE let's you save your finished path as a KML file, that can easily be converted into vector files for use in many mapping programs, WLL's path tool just made a thick line on top of the image.  Not very useful for a map maker.

So, I did what any respectable GIS geek would do, I worked with the WLL imagery to make it fit into my mapping program.  Frequent readers know that I primarily use two different mapping programs: Global Mapper and Marplot.  Both offer me the ability to create EVS precision maps easily and cost-effectively.  I can georectify quickly using Marplot, so that became my mapping program for this project.

This Flickr slideshow begins with my first modified image of Caldey Island, an overview of the island.  The next five images are of detailed sections at a scale of 1:200-meters from which I could digitize the shoreline with a high degree of precision.

WLL Modified Images in Marplot - Ready to Digitize Shorelines

I took these images and stitched them together in Marplot and ended up with the above georectified image.  How was it georectified?  I aligned the images using my previous EVS shoreline of the island as a guide.  No! It is not as precise as other methods, but for the purposes of this exercise and in the absence of quality ground control points, this will do.  I worked at 1:5,000 and created five distinct layers of information in addition to my new shoreline.

Caldey Island - Marplot Map (1:12,500)

My additional layers of information are the result of a quick photo interpretation of the base imagery.  If this map were to be produced for commercial use a more careful, systematic study would have generated a number of other useful layers of information.

WLL has some great imagery that I would love to be able to work with in my EVS mapping.  However, it requires a great deal of image manipulation before a mapmaker can make a map.

Alex Daley, Technical Evangelist of Microsoft's Virtual Earth Business Unit, please evangelize the enhancement of WLL to include robust map-making tools.  The GIS geeks of the world would be most appreciative.

Enjoy!

Posted by Mr Minton at 10/14/2006 03:43:00 PM | Permalink | Comments | links to this post

Manuhangi Atoll - Landsat Image S-07-15_2000

Manuhangi Atoll - Marplot Map

Manuhangi Atoll (19˚12'05"S., 141˚14'50"W.) is a small atoll that lies 29 miles W of Paraoa. There is no entrance to the lagoon.

(SD Pub-126)

About the only substantive information I could find on this island was in the Seamount Catalog maintained by Seamount Biogeosciences Network. This catalog contains a number of interesting images along with map files for seamounts throughout the world. I use it occasionally to gather proximital information.

Additional information is available at UNEP Islands Directory - Manuhangi Atoll.

Manuhangi Atoll is reported to be uninhabited, but visited occasionally by villagers from a nearby atoll. Most probably they come to harvest copra or to fish.

This project was actually completed quickly. The Landsat image is too "washed out" and consequently much of the otherwise visible details are "washed out". GE does not have any imagery for this atoll, just a blob. The only shuttle image is of poor quality. So you work with the best imagery possible and construct a map. My EVS shoreline tracks the visible Landsat shoreline better than the PGS shoreline does.

Enjoy!

Labels: atoll, EVS, Global Mapper, island, Landsat, map, Marplot, Pacific, Polynesia, Tuamotus

Posted by Mr Minton at 10/14/2006 09:20:00 AM | Permalink | Comments | links to this post

Atoll Tematangi - Landsat Image S-07-20_2000

Tematangi (Tematagi) (21˚40'S., 140˚37'W.) is the farthest W of the dependencies of Iles Gambier. The atoll is about 7 miles in extent. The sea breaks violently on some coral blocks on the NW side. Landing is fairly easy and safe a few hundred meters N of the SW point of the atoll; there is no pass into the lagoon.

A rocky spit, with a depth of 3m, extends about 1.5 miles SE from the SE extremity of the atoll. (SD Pub 126)

Tematangi Atoll - Marplot Map

This map took about 4-hours to complete. I digitize small sections of the image, upload into Marplot, process and save. Each small section (this map was made up of about 6-sections) is complete when finished processing. The final layers are the various reefs. I am trying something new by posting my images into my Flickr account. If you want a copy of the images I use, you can download them from Flickr.

Tematangi Atoll - Google Earth

I did want you to see an image of Tematangi Atoll used in Google Earth. For whatever reason they have a lousy set of images for many ocean islands. Specifically, most of the islands in French Polynesia and the Marquesas look like the above image. I guess they haven't gotten around to downloading the free images at NASA Applied Sciences Directorate.

Enjoy!

Labels: atoll, EVS, Global Mapper, island, Landsat, map, Marplot, Pacific, Polynesia, Tuamotus

Posted by Mr Minton at 10/12/2006 10:55:00 PM | Permalink | Comments | links to this post

Suvorov Atoll - Landsat Image S-03-10_2000

Suvorov Atoll - Marplot Map

Suwarrow Atoll (13˚16'S., 163˚06'W.) consists of several wooded islets lying on a barrier reef which encloses a lagoon. Anchorage Island on the NE side and High Island on the W side of the island are covered with coconut trees from 18 to 25m high; they are easily recognized. The barrier reef shows a little above HW. It is dangerous to approach the reef on its S or SE side unless the weather is clear. The N side projects to a sharp point; on the E side of it, there are some islets covered with brush.

Northeast Reef lies about 0.5 mile E of Anchorage Island and forms the E side of the entrance. East Reef lies 0.3 mile E of the S extremity of Anchorage Island, and South Reef lies about 0.2 mile SSW of East Reef. South and East Reefs can be distinctly seen from 3 miles.

The coast in the vicinity of the passage is said to be dangerous to approach at night due to irregularities in the line of the barrier reef. The lagoon entrance is just E of Anchorage Island. A vessel, with a draft of 4.6m, can use the channel between Anchorage Island and South Reef, but caution and local knowledge is necessary. Currents in the lagoon entrance are irregular. Rates on the flood reach 0.5 to 1 knot, while the ebb flows at rates of 2 to 3 knots. At the anchorage within the lagoon, the ebb current starts about 1 hour 30 minutes before HW.

Suvorov Atoll - Marplot Map (Detail) Entrance to the Lagoon

Anchorage.—Anchorage, unsafe in N weather, may be taken inside the lagoon, 0.2 mile off the W side of Anchorage Island, in a depth of 33m.

(SD Pub-126)

Suvorov Atoll (aka Suwarrow) is made up of many little islands scattered around the barrier reef. The islands are low to the water and are not safe in storm tossed seas. According to sailors that write on their blog sites, the islands in the north have a caretaker that ensures the safety of the islands.

This was the home of Tom Neale, a guy who decided to get away from it all. He escaped to Suvorov and stayed "away from the world of man" ("Joe vs The Volcano"). He stayed on the island two separate times and loved it, both times. The above link will give you more detailed information.

This island took about 6-hours to complete. I divided the work into two sessions. The reefs were fairly complicated to digitize. The finished map consists of 14-different layers of information. The island map turned out quite nice. The finished map was as much fun to admire as the process to complete it was.

Enjoy!

Labels: atoll, Cook Islands, EVS, island, Landsat, map, Marplot, Pacific

Posted by Mr Minton at 10/12/2006 10:25:00 PM | Permalink | Comments | links to this post

Niau Atoll - Landsat Image S-06-15_2000

Niau Atoll - ESA Image 2006 Oct 9

Niau Atoll - Marplot Map

Niau (16˚09'S., 146˚22'W.) lies 17 miles SW of Toau. This circular island, 5 miles in diameter and 8m high, is covered with forest, and visible from a distance of 12 miles.

The population was 160 in 1996. The town of Tupani, to the NE of the island, is well visible from sea and has an open basin where craft can approach even in moderate wind from the E. Another landing point is located to the NW of the island, on a sandy beach in front of the abandoned town of Ofare.

Vessels can anchor, in E winds, in 25m, in front of the village, and 100m from the reef. There is a radio station at the town of Tupana. The current in the vicinity of Niau is strong, sometimes setting W and E. (SD Pub-126)

Finally, I am back in the Tuamotus. Niau Atoll was relatively easy to digitize. I was able to determine the reef by using the "Color Dodge" effect in Global Mapper on the image. I also determined the two large wetlands using that effect. The balance of the work was done using a typical Landsat ETM+ 2000 image and a "No Blend" effect. The project took about 3-hours to complete, map and post. It was fun to work on.

Enjoy!

Labels: atoll, EVS, Global Mapper, island, Landsat, map, Marplot, Pacific, Polynesia, Tuamotus

Posted by Mr Minton at 10/12/2006 10:10:00 PM | Permalink | Comments | links to this post

Makatea Island - Landsat Image S-02-15_2000

Makatea Island - Marplot Map

Makatea Island - Marplot Map with Contours South (1-31,250)

Makatea Island - Marplot Map with Contours North (1-31,250)

Makatea Island (15˚50'S., 148˚15'W.) is an island about 4 miles in extent in a NW-SE direction. The highest point of the island, 110m high, is near its N extremity. The island can be seen at 20 miles. Cliffs border the island and at the foot there is a narrow strip of low ground which is covered with coconut trees. (SD Pub-126)

Islands throughout the Tuamotus are typically low-lying atolls, maybe 4 to 5-meters high. There is, however, the occasional island that is different in geologic structure. Makatea Island is one of these "different" islands. The island type is called "makatea" which is a dramatically uplifted island. This island has cliffs that are 80-meters high. A French Polynesian website titled "Makatea" is a tremendous source of information about the above specific island. It tells the story of phospate mining in the center of the island. A practice that ended in 1966. The island is reported to be uninhabited. Photographs of the island depict dramatic cliffs the make up much of the island's shoreline.

The mapping of the island was fast, as the image is cloud-free and the shoreline relatively uncomplicated. The most difficult feature to map was the sand features and the phosphate extraction scar in the center of the island.

Enjoy!

Labels: atoll, EVS, Global Mapper, island, Landsat, map, Marplot, Pacific, Polynesia, Tuamotus

Posted by Mr Minton at 10/11/2006 11:15:00 PM | Permalink | Comments | links to this post

Guinni Koma - Landsat Image N-38-10_2000

Guinni Koma - Marplot Map

Guinni Koma (Grande lle du Diable) (11°32'N., 42°32'E.), 166m high and about 0.1 mile SE of the above islet, is steep and of a yellowish-red color. The passage between these two islets has general depths of 14.6 to 22m, but an 8.5m patch lies in mid-channel. This patch can be avoided by passing close to Guinni Koma. The coral shoal extending from the smaller islet is visible at all stages of the tide and is easily avoided.

Anchorage can be taken, in a depth of 29m, about 0.1 mile W of the middle of the W side of Guinni Koma. The space is limited by the extending reefs and the great depths close W of the anchorage. This anchorage is sheltered, but violent squalls occasionally come down from Guinni Koma.

Petite Ile du Diable (11°32'N., 42°32'E.), 80m high, lies close SE of the SW entrance point of the above inlet. The lava on the coast of this island is clearly visible. A coral shoal extends about 137m S and 0.1 mile W from the islet.

I mapped this coastline and islands about 6-months ago. I only posted a few of the islands. These two were not posted. Gunni Koma is part of a volcano. Here is a picture of it from the shore. The other site I have found that discusses the islands is an Excursion to this region. It is in French, but the photos are wonderful.

Enjoy!

Labels: Djibouti, EVS, island, Landsat, map, Marplot, volcano

Posted by Mr Minton at 10/11/2006 01:11:00 PM | Permalink | Comments | links to this post

Abou Maya - Landsat Image N-38-10_2000

Abou Maya - Marplot Map

This map is more about a natural "choke point" and only a little about islands. I think that islands, no matter how small they are, that are part of a "choke point" are fascinating. They become larger than their actual size. Abou Maya Island is located in Djibouti. It is 185-meters from the northern shore and 500-meters from the southern shore. It turns out that the northern pass is the deeper one. Ghoubbet Kharab is the bay that Abou Maya fronts.

As I was preparing to republish this map I noticed that the WVS layer was turned on along with the EVS layer. Everytime I compare the two layers, my zeal to produce a new level of mapping accuracy is reinforced. The world needs an improved "free" shoreline map - Enhanced Vector Shoreline

Enjoy!

Labels: Djibouti, EVS, Indian, island, Landsat, map, Marplot

Posted by Mr Minton at 10/11/2006 01:10:00 PM | Permalink | Comments | links to this post

To date, I have created and posted over 129 Island Projects. Each project consists of a minimum of: 1) the Landsat image used in creation of the shoreline and other layers of information. 2) Map of the island, either showing shoreline only or including other layers of information. 3) Any additional information that might reveal aspects of the island to my readers. My (SS) posts contain Flickr slideshows which often consists of many images, both Landsat, GE and maps, of the island project.

My Thoughts are just that, things that interest me or might interest my readers. The thoughts are my free-form opportunities to express myself. Some of them are rants, some are dinky and some are heart-felt aspirations. Almost all of them are GIS-related.

I am not a programmer. I know enough HTML to fashion this blog. Most of the look and feel of this site comes from snippets of code made available through the generosity of countless souls trying to make the Internet an easier place to work in. I am not a professional cartographer/photogrammetrist. Those in the profession have my sincere admiration for what they do. I am a map-maker. My maps contain a specific set of data - vectors that delineate shorelines derived from Landsat ETM+ 2000 imagery. I create vector shorelines, Enhanced Vector Shorelines (EVS). Consequently, I am confident sharing my How To ideas with my readers. These ideas typically focus on experiences gained during work on mapping projects. I believe there are many excellent ways to construct the maps that I make, but I follow my methods and will share them with you.

The last two types of posts are Data, which is typically very popular. The data I seek out and share is almost always free. It might require some work to get it into your mapping software, but it can be done. The data I share typically becomes a layer of information on my world map, so, I know, it can become a layer on your world as well. The second and last type of post is my Comparison. It happens when I find something that could and should be visually compared. My comparisons are typically done side-by-side. They should never be viewed as an "end all". The comparisons are my attempts to better understand an item of interest.

Use the View link to connect to a post of interest.

I hope you enjoy my efforts! I trust you will find them helpful, informative, fascinating and entertaining. For those of you that are living hectic, stressful lives, take a journey to one of my islands and relax. We all deserve a break.

Enjoy!

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View 10/11/2006 Makatea Island FP (Repost)

View 10/11/2006 Canton Atoll KR (Repost)

View 10/11/2006 Guinni Koma DJ (Repost)

View 10/11/2006 Abou Maya DJ (Repost)

View 10/10/2006 Comparison - EVS to GE Georectification

View 10/09/2006 Thoughts - Antipode of Qibla at Mecca (SS)

View 10/05/2006 Data - EVS Caspian Sea Shorelines

View 10/01/2006 Cu Lao Cham VN (SS)

View 10/01/2006 Thoughts - When is a Shoreline a Shoreline? (SS)

View 9/27/2006 Data - Free Benthic Habitats Map Files of Pacific Isles (SS)

View 9/27/2006 Isla San Benedicto MX (SS)

View 9/27/2006 Paraoa Atoll FP (SS)

View 9/22/2006 Data - World Shorelines @ 1:5,000,000 (Marplot) (SS)

View 9/21/2006 Minami-Tori-Shima (aka Marcus) JA

View 9/20/2006 Data - Global Bathymetry on the Cheap (SS)

View 9/18/2006 Isla Monserrat MX (SS)

View 9/17/2006 Pingelap Atoll FM (SS)

View 9/13/2006 Isla Alejandro Selkirk CI (SS)

View 9/13/2006 Thoughts - Kid's Play and ESRI's ARC GIS or Marplot?

View 9/11/2006 Thoughts - Digitizing is Child's Play

View 9/10/2006 Thoughts - Let's Get Lost

View 9/09/2006 Baker and Howland Islands US (SS)

View 9/09/2006 Darnley Island (aka Erub) AS (SS)

View 9/08/2006 Thoughts - "EVS" Means "Whatever"

View 9/06/2006 Comparison - Navteq River vs EVS River (SS)

View 9/06/2006 Thoughts - To All of You Searching For "EVS, Australia"

View 9/06/2006 Lake Kapchagai KZ - An Ambitious Digitizing Project (SS)

View 9/04/2006 Minami-Daito Jima JA (SS)

View 9/03/2006 How To Make a Map of a River at EVS Precision (SS)

View 8/31/2006 Isla Carmen MX (SS)

View 8/31/2006 Data - Free Digital Mexican Topos (1:250,000)

View 8/29/2006 Thoughts - Current Projects & Plans for Student Mappers

View 8/28/2006 Thoughts - Nukuoro Atoll FM & Korea's Fascination

View 8/27/2006 Isla del Espiritu Santo MX & Isla Partida MX (SS)

View 8/26/2006 Thoughts - 101 Countries and Counting

View 8/23/2006 Thoughts - How About Some Feedback on My Efforts?

View 8/22/2006 Clarion Island MX (SS)

View 8/20/2006 Thoughts - 2-Steps Forward, 1-Step Sideways, 1-Step Back

View 8/19/2006 Nikumaroro Atoll KR (SS)

View 8/18/2006 How to Make a Map Using Google Earth's KML - Revised (SS)

View 8/17/2006 Groupe Acteon FP (SS)

View 8/16/2006 Thoughts - PGS to EVS Precision Needs To Be A Reality

View 8/13/2006 Temoe Atoll FP (SS)

View 8/11/2006 Marutea Atoll FP (SS)

View 8/10/2006 Comparison - LINZ 1:25,000 Map to EVS Map (SS)

View 8/10/2006 Thoughts - For Your Viewing Pleasure: Pacific Atolls

View 8/08/2006 How To Show Off Your Projects With Flickr & Badgr

View 8/08/2006 How To Make A Map: Image To Map (SS)

View 8/07/2006 Thoughts - ESRI's Party & I Got To Go!

View 8/07/2006 Thoughts - My Blog's Look Has Changed

View 8/04/2006 Morane Atoll FP (SS)

View 8/03/2006 Fernando de Noronha BR

View 8/02/2006 How To Convert PGS Map Files into KML/KMZ

View 8/02/2006 Data - Example of Seamount Catalog Map Image

View 8/02/2006 Manuhangi Atoll FP

View 7/29/2006 Data - USGS Earthquake Locations 1973-2006

View 7/28/2006 Thoughts - ESRI's Private Shin-dig & I Can Attend

View 7/28/2006 Thoughts - ESRI's Private Shin-dig & I Can't Attend

View 7/28/2006 Gambier Islands FP

View 7/27/2006 Okino-tori-shima JA - When is a Reef an Island?

View 7/26/2006 Delos Island GR with GE 1-Meter Shoreline

View 7/25/2006 Comparison - PGS, WVS, EVS & 1-Meter Shorelines

View 7/24/2006 How To Adjust PGS to EVS Precision: Example & Thoughts

View 7/23/2006 Nisos Psara GR

View 7/23/2006 Nisos Symi GR

View 7/22/2006 Thoughts - PGS Stutter & Sharp Turn Vectors

View 7/19/2006 How to Adjust PGS to EVS Precision: The Quest Continues

View 7/18/2006 Thoughts - What I Do For Fun, Besides Maps

View 7/17/2006 How To Work With 1-Meter Google Earth Imagery

View 7/16/2006 Namorik Atoll MH

View 7/13/2006 Comparison - Gavdos Island EVS vs PGS

View 7/13/2006 Thoughts - Don't Worry, Be Happy! Island Life is #1!

View 7/11/2006 Nukuoro Atoll FM - Motus with Names

View 7/11/2006 Nukuoro Atoll FM

View 7/07/2006 Rapa Island FP

View 7/06/2006 Thoughts - Construct your Own World Shoreline Map (1)

View 7/06/2006 Thoughts - Construct your Own World Shoreline Map (2)

View 7/05/2006 Comparison - EVS, PGS, WVS & SRTM (1) Shorelines

View 7/04/2006 Comparison - Admiralty: French Admiralty & EVS

View 7/03/2006 Atoll Kaukura FP

View 6/28/2006 Isla Conchaguita ES

View 6/24/2006 How To Adjust PGS to EVS Precision

View 6/22/2006 Comparison - WVS, EVS, PGS & GEVS

View 6/20/2006 Adalar Islands TU

View 6/19/2006 Rose Atoll AS

View 6/19/2006 Data - Limits in The Seas

View 6/17/2006 Pukapuka Atoll CW

View 6/14/2006 Comparison - PGS vs EVS: Pukapuka Atoll CW

View 6/14/2006 Comparison - PGS vs EVS: You Decide

View 6/13/2006 Data - Improved WVS? Rival EVS? What's Going On?

View 6/11/2006 Caldey Island UK

View 6/10/2006 Lan-yu Tao TW

View 6/09/2006 Comparison - More on SWBD & EVS Shorelines

View 6/06/2006 Comparison - SWBD, WVS & EVS

View 6/06/2006 Thoughts - Crashing System & The End of the School Year

View 6/06/2006 Kuei-shan Tao TW

View 6/03/2006 Thoughts - Enhanced Vector Shorelines - My Vision

View 6/03/2006 Makatea Island FP

View 6/01/2006 Data - Australian Estuaries

View 5/29/2006 How To Make A Map: Image to Map

View 5/28/2006 Niau Atoll FP

View 5/27/2006 Data - Ni'ihau Island HW - Using The USGS HDC Free Data

View 5/26/2006 Data - Free Fantastic Data for Hawaiian Islands

View 5/25/2006 Ma-tsu Tao TW

View 5/24/2006 Peng-hu Tao TW

View 5/23/2006 How To Contact Me to Get Free Map Files?

View 5/21/2006 Data - Free Caspian Sea Contours

View 5/19/2006 Pulau Bankobankoang ID

View 5/18/2006 How To Find Hidden Reefs

View 5/16/2006 Data - Anybody Need World Port Index (WPI) Data?

View 5/15/2006 Thoughts - How Many Islands To Map?

View 5/14/2006 Pulau Kalukalukuang ID

View 5/13/2006 Comparison - Lundy Island Shoreline Map Projections

View 5/13/2006 Comparison - JPEG, MrSid, TIFF

View 5/12/2006 Lundy Island UK

View 5/11/2006 Comparison - UK Ordinance Survey 1948 & Landsat ETM+

View 5/10/2006 Isle of Wight UK

View 5/10/2006 Thoughts - Landsat Coverage & My Shoreline Quest

View 5/09/2006 Peng-hu Tao TW

View 5/09/2006 Peng-hu Tao (Middle Group) TW

View 5/07/2006 Data - How To Snag Free Landsat Imagery (WRS-1 or -2)

View 5/07/2006 How To Handle Clouds: Shoreline Obscurers

View 5/07/2006 Eiao FP

View 5/05/2006 Guinni Koma DJ

View 5/04/2006 Marotiri FP

View 5/03/2006 Thoughts - Maps and RSGBIOTA

View 5/03/2006 Iles Moucha DJ

View 5/02/2006 Thoughts - If All The World Were Imaged at 1-Meter

View 5/02/2006 Nisos Dilos GR

View 5/01/2006 Pinaki Atoll FP

View 5/01/2006 Oeno Atoll PC

View 5/01/2006 Henderson Island PC

View 5/01/2006 How To Use Greasemonkey, Script and Tags

View 4/30/2006 Peng-hu Tao (Southern Group) TW

View 4/30/2006 Taiwan TW

View 4/29/2006 Iles Glorieuse GO

View 4/29/2006 Isla Asuncion MX

View 4/29/2006 Isla San Roque MX

View 4/27/2006 Thoughts - Raster vs Vector - An Explanation

View 4/27/2006 Thoughts - Raster or Vector - Which Is Best?

View 4/26/2006 Nisidhes Fournoi GR

View 4/25/2006 Howland Island US

View 4/25/2006 Islas Coronados MX

View 4/24/2006 Thoughts - Be Careful You Map-Makers!

View 4/23/2006 Thoughts - Want To See a Partially Completed EVS Project?

View 4/21/2006 Swains Island AS

View 4/21/2006 Thoughts - CoastChart and Me - Coastlines of Africa

View 4/21/2006 Penon de Alhucemas and Other Islands SP/MO

View 4/20/2006 Motu One FP

View 4/19/2006 Bulgarian Islands BU

View 4/18/2006 Dumera Deset DJ/ER

View 4/18/2006 Swabi' Islands DJ

View 4/17/2006 Barim Island YM

View 4/17/2006 Miyako-Retto JA

View 4/17/2006 Outlying Islands of Miyako-Retto JA

View 4/17/2006 Yaeyama-Retto JA

View 4/17/2006 Iriomote-Jima JA

View 4/17/2006 Ishigaki-Jima JA

View 4/17/2006 Central Group of Yaeyama-Retto JA

View 4/17/2006 Outlying Islands of Yaeyama-Retto JA

View 4/14/2006 Nisos Patmos GR

View 4/14/2006 Nisos Pserimos GR

View 4/12/2006 Nassau Island CW

View 4/11/2006 Suvorov Atoll CW

View 4/10/2006 Thoughts - EVS Worldwide Map: My Vision

View 4/09/2006 Southern Cook Islands CW

View 4/09/2006 Mauke Atoll CW

View 4/09/2006 Mitiaro Atoll CW

View 4/08/2006 Thoughts - Many Greek Islands to Post. Are You Interested?

View 4/08/2006 Nisos Nisyros GR

View 4/08/2006 Geyikova Adasi TU

View 4/06/2006 How To View My Maps and Images

View 4/05/2006 Manuae Atoll CW

View 4/05/2006 Thoughts - Not For Nautical Purposes!

View 4/04/2006 Nisos Gavdos GR

View 4/04/2006 Atiu Island CW

View 4/04/2006 Thoughts - Global Mapper, Marplot and My Maps

View 4/03/2006 Takutea Island CW

View 4/03/2006 Thoughts - Any Interest In My Completed Greek Islands?

View 4/02/2006 Palmerston Atoll CW

View 3/31/2006 Tepoto Island FP

View 3/30/2006 How To Make a Map: Landsat to Marplot to Maps

View 3/30/2006 Thoughts - Reworking the Layers

View 3/30/2006 Data - UNEP Islands and My Projects

View 3/30/2006 Comparison - Landsat Images & NOAA Charts: They Match!

View 3/30/2006 Thoughts - Why I Use Flickr

View 3/30/2006 Thoughts - Mapping Progress in the Tuamotus

View 3/29/2006 Atoll Vahitahi FP

View 3/28/2006 Socorro Island MX

View 3/28/2006 Isla San Benedicto MX

View 3/26/2006 Atoll Vairaatea FP

View 3/25/2006 Isla Partida MX

View 3/25/2006 Atoll Tureia FP

View 3/23/2006 Aitutaki Atoll CW

View 3/18/2006 Akiaki Island FP

View 3/18/2006 Nukutavake Island FP

View 3/17/2006 Ahunui Atoll FP

View 3/12/2006 Atoll Manuae FP

View 3/08/2006 Atoll Vanavana FP

View 3/07/2006 Phoenix Islands KR

View 3/04/2006 Orona Atoll KR

View 3/01/2006 Manra Atoll KR

View 2/28/2006 Rawaki Atoll KR

View 2/27/2006 Enderbury Atoll KR

View 2/26/2006 Birnie Atoll KR

View 2/24/2006 Iles du Duc de Gloucester FP

View 2/22/2006 McKean Atoll KR

View 2/21/2006 Atoll Nukutipipi FP

View 2/21/2006 Atoll Anuanu Ruga FP

View 2/21/2006 Atoll Anuanu Raro FP

View 2/21/2006 Atoll Hereheretue FP

View 2/15/2006 Ducie Atoll PC

View 2/14/2006 Ponam Island PP

View 2/14/2006 Atoll Tematangi FP

View 2/06/2006 Clipperton Island FR

View 1/21/2006 Atoll Maria Est FP

View 1/03/2006 Adalar Islands TU

View 1/02/2006 Hon Son Cha VN

View 12/31/2005 Cu Lao Cham VN

View 12/07/2005 Isla Danzante MX

View 12/06/2005 Isla Santa Catalina MX

View 11/29/2005 Isla Monserrat MX

View 11/20/2005 Isla del Espiritu Santo MX

View 4/10/2005 Buyukada, Adalar Islands TU

You will notice many titles contained in this list do not match the original post. I have standardized them to give them a consistent format. Eventually, I will do the same for each of my posts.

Posted by Mr Minton at 10/10/2006 09:00:00 AM | Permalink | Comments | links to this post

EVS Image with NGA PGS Shorelines Superimposed

As I worked on my previous post, Thoughts - Antipode of Qibla at Mecca, I asked myself once again "How does Google Earth image georectification compare with Landsat ETM+ 2000 image or with NGA PGS Shoreline data?"  So let's compare.  The above is my EVS Shoreline map which was constructed using Landsat ETM+ 2000 imagery.  I have marked a point on one of the northern motus with coordinates (decimal).  I have superimposed NGA PGS shorelines (in red) to show that they are very close to EVS precision.

GE Image with EVS Lat/Lon Compared to GE Lat/Lon

At this scale, approximately 1:25,000, the EVS Lat/Lon rests nearly atop the GE Lat/Lon.  At this resolution, EVS and GE seems to work together.  Now let's zoom so that we can see any difference between the points and then measure that difference.

EVS Lat/Lon Compared to GE Lat/Lon

The same point determined on two different images is only 12.33-meters apart. Using satellite imagery to snap a picture of moving earth and have a 12.33-meter wobble is doing very good.  That is unless you are going to build a house near the shore of this motu and it turns out your property is 12.33-meters from the shore and your house is now a houseboat.  Now that would be a problem.

Seriously, a 12.33-meter difference at the useful scale of these images is excellent.

Enjoy!

Posted by Mr Minton at 10/10/2006 06:05:00 AM | Permalink | Comments | links to this post

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!

Posted by Mr Minton at 10/09/2006 06:40:00 AM | Permalink | Comments | links to this post