EVS-Islands

Kalukalukuang Group - Landsat Image (S-50-05_2000)

I am currently mapping the above group of islands. They looked interesting. Also, their images were very sharp making the map making process relatively easy. The challenge when mapping an atoll is always the reef system. My early effort at reef mapping was to create a polygon that encompassed all visible reefs and call it EVS-Reef. Now I use a complex series of layers, a minimum of 10 different reef layers, that are often readily discernable.

Kalukalukuang Group - Map

I have created two of the island maps for this group. The other islands in the group are shown on the above map as WVS red outlines. The two islands have detailed renderings of their respective reef systems that are discernable from the Landsat image. (See previous post for Palau Kalukalukuang ID).

Kalukalukuang Group - Map (AMS SB 50-7 Series T503)

However, I was curious after studying the AMS map of the Kalukalukuang Group. I saw a much larger reef system that was not too far beneath the surface of the water. Where was this reef system using Landsat imagery. Global Mapper gives you options to create effects on your images that can sometimes allow you to see what was previously not visible. The initial effect is always "No Blend". It is how I typically work when digitizing shorelines. I have used the other effects (16 different ones) and have varied the darker-to-lighter effect as well. I still prefer "No Blend" for almost all of my projects. But what about those reefs? Where were they?

Kalukalukuang Group - Map Reliability (AMS SB 50-7 Series T503)

The AMS map relied on aerial photos to construct their original map. The bulk of their work was based on imagery gathered between 1922 through the 1950s. Using that imagery they showed outlines of the reefs. But it appeared Landsat didn't find them.

Kalukalukuang Group - Image Effect Color Dodge

I tried an effect called "Color Dodge" and the following showed up. The clouds show up as bands flowing up or down the image. However, the curious yellow signatures were part of that hidden reef. In fact, it is the reef system and it shows up clearly using the "Color Dodge" effect.

Kalukalukuang Group - Comparison of Effects

The final image shows the same area using both effects (Top - No Blend; Bottom - Color Dodge). So the hidden reefs were unhidden. My future maps of atolls will require that I employ the "Color Dodge" or "Color Burn" effects to display and map any hidden reefs.

Posted by Mr Minton at 5/18/2006 06:33:00 AM | Permalink | Comments | links to this post

WPI data is contained in my world map as an important data layer. In fact, some of my island maps posted here contain an anchor (my symbol for a port) along with the name. I do not make full use of the information contained within the WPI. My projects contain the name of the port plotted per the port's assigned lat/lon. Some of you might require more in-depth information on the ports. The US government pub you need is WPI Pub-150.

The World Port Index (Pub 150) publication contains the location, characteristics, known facilities, and available services of major ports, shipping facilities and oil terminals throughout the world (approximately 64,000 entries). The data in this publication is mostly tabular and new editions are published bi-annually. This publication is available in its entirety on the website and there are also database queries available for all of the port information contained within.

This pub is freely available at the Maritime Safety Information web page.

I am a map data hound. I scour the web to find FREE information. In another life, I used to sell repackaged US government data. It amazed me that smart people would pay good money for free information. However, after spending 15-years in the information industry I know now that "time is money". The entrepreneur repackages the free information in a useful format so that the end-user saves time (money). It costs less money (time) than the time (money) one would have to spend to compile their own database.

So, if you would like, there are a number of companies that will gladly sell you WPI data. They probably will charge you handsomely. Or you could follow the above link, download the WPI Access data, load it into MS Access, export the WPI data as an MS Excel file and then create a text file that can be loaded into your mapping program (or maybe your program handles MS Access or MS Excel). It all sounds so easy to me, but I do appreciate the difficulty some of you might have. If you require a map-ready file (shp), drop me a comment with your email address and I'll fix you up.

OT: Data

Posted by Mr Minton at 5/16/2006 08:42:00 AM | Permalink | Comments | links to this post

I have a couple of goals that I have shared with my visitors: 1) to map world shorelines and 2) to specifically focus my mapping efforts on island shorelines. By accomplishing 2) I will get to 1). Yes, the project is overwhelming. For a lone mapper, it is a quest worthy of Don Quixote.

How many islands are there scattered about the world? I spent a summer, 4-years ago, downloading island name point data from the GEOnet Names Server. 134,873 points later, I had my Islands of the World database. I sifted and sorted until I had 118,691 named islands, atolls and island groups. I isolated another group of 16,132 very small islands identified as rocks. I noted that many of the islands carried the same geographic coordinates. The listed was sifted and sorted again until I had isolated unique islands (No duplicate points). The list now stands at 68,674 islands, not counting rocks.

As I have mapped islands the number of islands has grown. Atolls, typically named by a single point, contain many individual islands (motus). My number of islands has grown significantly. The bulk of the islands will carry a label of "Name Unknown".

What is the final count? Are there 68,674 only? Are there 250,000 if you count the "Name Unknown"? I don't know! I can firmly state that there are more islands than I will ever be able to map in my brief lifetime. So many shorelines to map, so little time.

OT: Thinking

Posted by Mr Minton at 5/15/2006 06:19:00 AM | Permalink | Comments | links to this post

Pualu Kalukalukuang - Landsat Image (S-50-05_2000)

Pualu Kalukalukuang - Map

Pulau Kalukalukuang (5°12'S., 117°40'E.), 59m high and covered with coconut palms, stands on the NW side of the bank about 48 miles NE of Sibbalds Banks. It was reported to be radar conspicuous at 24 miles, and is visible at least 12 miles in clear weather. A coral reef fringes the island. A light is shown from the N extremity of Pulau Kalukalukuang, and a racon transmits from the light. A shoal, with a depth of 12.2m, was reported to lie 9 miles S of the S extremity of Palau Kalukalukung.

There are no fantastic web sites for this island. It is part of an extensive coral reef. I wil tell you that as I researched this site I discovered a collection of Army Map Service 1:250,000 maps of Indonesia (all 13,000+ islands). These maps have been digitized and are part of the University of Texas Map Library. The details of Pulau Kalukalukuang are poor, as you would expect on a 1:250,000. The above map is at a scale of 1:50,000. Looks good, doesn't it?

Posted by Mr Minton at 5/14/2006 09:31:00 PM | Permalink | Comments | links to this post