Reao Atoll FP - Finished . . . At Last!

Reao Atoll

Reao Atoll - ISS004 Image Mosaic (1:70,000)

Reao Atoll - EEVS Precision Map (1:70,000)

Reao or Natūpe is an atoll in the eastern expanses of the Tuamotu group in French Polynesia. The closest land is Pukarua Atoll, located 48 km to the WNW.

Reao is 24.5 km long and its maximum width is 5 km. The whole length of its north-eastern rim is occupied by a single long island. There is no navigable pass into the lagoon.

Reao Atoll's population is 344 inhabitants.

That is about it for Reao Atoll on the internet. There might be some scattered bits of information, but nothing of newsworthy significance. Why? It could be the location. Unlike many of the other atolls making up the Tuamotus that receive numerous pleasure cruisers, Reao Atoll is situated away from the normal cruising routes. In addition the lagoon has no entrance for sailing vessels making for percarious landings on and off of the main island.

Even with the geographical difficulties associated with Reao Atoll, I wouldn't mind visiting. The southern end of the atoll looks a bit on the wild side. If not real wild, it looks to be far from the population center of the island located on it's northern end. One could perhaps find an isolated small motu along the atoll's western edge. There are in the neighborhood of 50 motus along this edge of the atoll. I am certain one of these small motus could offer one a few days of solitude. If not a few days, for sure a few hours.

Now for a few comments on the map. First, the base imagery is from ISS004. I took 3 excellent images and assembled them into a mosaic of the entire island. I rotated the image about 37° to align it with the atoll's true alignment. I had created a shoreline of Reao Atoll a few years back, but had not saved the georectified image. All I had to work with was the island polygons which came from the ISS004 imagery. I used over 37 GCPs (ground control points) to georectify the ISS004 image mosaic. It wasn't until this weekend that I had both time and energy to complete my typical four vector layers - island polygons, vegetation polygons, shallow reef polygon and lagoon polygon. I completed all of the layers as Phil Mickelson was busy winning the Masters for the 3rd time.

P.S. - Later that day, I compiled my first OSM formatted vector file consisting of the island polygons. Ultimately my goal is to place my EVS copyright free vectors onto OpenStreetMap. That is another story for later time.

Marutea Atoll Nord FP - An Uninhabited Atoll...Kind Of

Marutea Atoll Nord FP

Marutea Atoll Nord FP - Landsat ETM S-07-15_2000 Image (1:150,000)

A portion of the Landsat ETM+ image looks great, the other portion is cloud covered. If I had only used the Landsat image to create my EVS precision map, it would have been an incomplete effort. Fortunately, ISS imagery helped to fill in the gap.

Marutea Atoll Nord FP - ISS006E37438 Image Modified (1:150,000)

First I had to rotate the ISS image and georectify it to my Landsat base image. I was able to do it after much tweaking of the ISS image it was positioned properly for my mapping purposes. Many of the coral heads, which I classify as shallow reef, were derived from the ISS image.

Marutea Atoll Nord FP - EVs Precision Map (1-150,000)

And here is the finished map! If one requires hi-res imagery, it can be found in Google Earth. Located at the channel leading into the lagoon are a few houses. I suspect they are used by coconut or black pearl harvesters. Although the island is uninhabited, people frequent the atoll doing the things that people do, harvesting resources.

Looking at the DigitalGlobe imagery found in Google Earth, large stretches of the island appear to be without a sand covering. It looks as if the island was washed over by a typhoon or a storm surge. Perhaps someone with first hand knowledge might share more about this uninhabited atoll...kind of.

Enjoy!

Thoughts - Which Color Scheme Works Best for EVS Maps?

King George Islands FP

King George Islands FP - Landsat ETM S-06-10_2000 Image (1:175,000)

King George Islands FP - EVS Precision Map (1:175000)

Takapoto Atoll FP - EVS Precision Map (1:80,000)

I spent today digitizing the King George Islands located in the Tuamotu Islands FP. The top atoll, Takapoto, was just completed using my new NIMA color scheme. Not only am I limiting layers to EVS island projects to island polygon, reef shallow, lagoon and island water feature, but I've changed my color scheme to match NIMA's nautical charts. My current color scheme is as follows:

island polygon is R-245 G-245 B245

reef shallow polygon is R-205 G-225 B-235

lagoon is R-225 G-250 B-255.

Takaroa Atoll FP - EVS Precision Map (1:80,000)

Takaroa Atoll, completed a few months ago, contains my old color scheme:

island polygon is R-240 G-232 B-217

reef awash is R-208 G-234 B-224

reef shallow is R-153 G-214 B-236

lagoon is R-090 G-169 B-211

In both projects the vegetation layer R-157 G-179 B-151 and the deep ocean layer R-165 G-207 B-231 are unchanged.

For visual appeal, I like the old style. The NIMA nautical chart style gives a cleaner, crisper look. What do you think?

Enjoy!

Nosy Antaly-Be, MA - Fishermen, Tourists and WWII Japanese Midget Submarines

Nosy Antaly-Be, MA,

Nosy Antaly-Be, MA - DigitalGlobe Image from Google Earth (1:12,500)

Nosy Antaly-Be, MA - EEVS Precision Map (1:12,500)

Every so often I like to scout a coastline in Google Earth to find an interesting island to map. Nosy Antaly-Be's image is cloud-free, hi-resolution and located along the eastern shore of the northern peninsula of Madagascar. The two islands I mapped are the northern most of a cluster of islands that are just off shore as one enters Diego-Suarez Bay. I mapped these two islands because I was bored with my current project, remapping Papua New Guinea, a very big job. I wanted to make a pretty map and to use DigitalGlobe imagery. So far, so good!

I mapped the islands quickly and completed all of the additional details using Global Mapper. My cursory check for information concerning these two islands initially turned up nothing of great interest. The semi-permanent population was made up of fishermen and tourists. Then came the WWII Japanese midget submarines. In 1942 Japan flush with a number of victories in Southeast Asia looked to control the entire Indian Ocean. A key area to control was the northern end of Madagascar. From this vantage point they would have been able to intercept allied shipping with ease. They attacked ships located in Diego-Suarez Bay in May, 1942. One ship was damaged and another was sunk with a lose of 6 crewmen. If you would like to know more about the "Whys" and "What Fors" follow this link, Imperial Submarines. The article will give you loads of background information concerning Japanese midget submarines and the war in Madagascar.

Life never fails to intrigue me. I select two nondescript islands and they turn out to be used to screen Japanese ships prior to an attack on ships in Diego-Suarez Bay. Who would have thunk it.

Enjoy!

Caspian Sea Isobaths from Russian Topographic Maps

Caspian Sea Isobaths - Taken from 1:1,000,000 Mapping

Caspian Sea Isobaths - Entire Sea (1:5,000,000)

If I'm not careful, I can turn a finite mapping project into a never ending task, one that requires tweaks on top of tweaks. My Caspian Sea isobaths fall into that type of project. I have worked on the Caspian Sea shoreline and now isobaths since 2006 and I'm still not finished. The northern shore, including the Volga River delta remain my final shoreline to map. At my current rate I should be finished around 2012. In the mean time I would like to share my recently completed Caspian Sea isobaths. These isobaths were taken from Russian topographic maps downloaded from Poehali.org. One can download Russian topographic maps for free. The maps are georeferenced and load easily into most mapping programs. My Caspian Sea topographic map is a mosaic of 65 individual maps at scales between 1:500,000 to 1:100,000. All of these maps contain isobaths. Using the most detailed scale, I constructed the following isobaths: -10m, -20m, -50m, -100m, -150m, -200m, -300m, -400m, -500m, and -700m. Compared to the other Caspian Sea isobaths, mine differ. I hesitate to claim my isobaths are more accurate. I suspect they are, as they were derived from 1:500,000 to 1:100,000 scale maps. The other isobaths were taken from 1:1,000,000 scale maps.

Caspian Sea Isobaths - Baku Vicinity (1:250,000)

Where my isobaths prove most interesting is when one zooms into an area. An interesting area to study these isobaths is around Baku, the site of many oil rigs. The isobaths twist and turn in and around oil rigs as one would expect.

Caspian Sea Isobaths - Baku Vicinity Offshore (1:62,500))

Currently, my Caspian Sea isobaths are quietly residing on my hard drive. Before I do anything with them, other than my own mapping, I need to secure permission from Poehali.org. I know I did an excellent job tracing these unique isobaths. Not sure this is going to be a "give away". Would love to make a buck or two off of this data set. We'll see.

Enjoy!

Thoughts - North Sentinel Island Five Years After the "Big" One

North Sentinel Island - Pre December 26, 2004

North Sentinel Island is home to a few hundred of the most isolated people on the earth. This group of people has chosen to remain separate from all other peoples. To the credit of India, they have been allowed to remain separate. Prior to December 26, 2004, the inhabitants were content to hunt and gather on their small forest covered island. Then came the dreadful 9.0 earthquake that caused death and destruction throughout this part of the world. North Sentinel Island was not spared. It is unclear if any of the inhabitants were killed as a result of the earthquake. What is clear is that the island underwent a dramatic transformation. This small island was thrust upward. The submerged reef was no longer submerged.

North Sentinel Island - February 2005

The February 2005 image shows the once submerged reef exposed above water. The forest is intact, but the island's fringing reef is now permanently above water. The stark white indicates that the reef is a new comer to the above-water environment.

North Sentinel Island - November 20, 2009

Fast forward to last month and one sees the reef still above water, but undergoing a gradual color change. As the once bone white reef remains in contact with the outside air, dust particles are blown onto the reef daily, algae colonies live and die and organic debris flows out from the island proper onto the reef, all of this contributing to the raised reef's gradual discoloration.

North Sentinel Island - EEVS Precision Map (1:62,500)

My post-earthquake map still gives a good picture of this small uplifted island. I'm glad it remains isolated and it's inhabitants have yet to encounter the world of modern man.

Enjoy!

Thoughts - They Aren't as Good as EVS Precision and That's the Fact , Jack!

Olimarao Atoll Locator Map

You all remember my last post, Olimarao Atoll? I spent a few days prior to posting it doing research into available online mapping. I checked out the standard mapping packages for Olimarao Atoll vicinity maps. Check out my results below...

Olimarao Atoll - Vicinity Map from Google Maps - Some land polygons, no labels.

Olimarao Atoll - Vicinity Map from Yahoo Local Maps - Nothing here.

Olimarao Atoll - Vicinity Map from Bing Maps - And nothing here.

Olimarao Atoll - Vicinity Map from OpenStreetMap - Land polygons and labels.

Google, Yahoo and Bing Maps rely on satellite imagery. The underlying maps of these oceanic island areas are largely neglected in map coverage. Google Maps provides land polygons from a mapping file similar to WVS 1:250,000. OpenStreetMap uses NGA PGS polygons along with NGA Country name files. Clearly the superior map product for oceanic islands is found on OpenStreetMap. But wait! What about a vicinity map using what I call EVS rough precision digitizing. Using Landsat ETM+ imagery, I could quickly digitize island polygons and reefs giving a much clearer map of the island.

Elato, Lomolior and Olimarao Atolls - Landsat N55-05_2000 Coverage

Landsat N55-05_2000 is the imagery I initially tried to work with. As you can see, The vicinity is not covered. It is a blank. So I did what any good mapper would do, improvised. Using Google Earth, I found the blank area and DigitalGlobe had hi-res imagery of the islands located within the blank area.

Elato and Lomolior Atolls - DG Preview Image from GE

Elato and Lomolior Atolls - DG Preview Image from GE Cropped

I decided to use the DG Image Preview from GE. I copied it, cropped it and georectified it. From there, I was able to complete the digitizing within a few minutes. I did this for all islands within the Landsat blank area. Atolls should have reefs digitized as they make up a critically important aspect of this feature. My finished map uses five layers - 1) land polygon 2) reef shallow 3) reef deep 4) ocean and 5) name labels. My island name layer is an extract from NGA's country files.

Olimarao Atoll - Vicinity Map from EVS Rough Precision (1-500,000)

This was all done using Global Mapper. The scale for the above map is 1:500,000. Now that is what I call a real oceanic island vicinity map.

Enjoy!