Thoughts - Where the Shore Meet's the Water's Edge

Where the Shore Meets the Water's Edge

Okay, all of you ESA Mars Express followers know that this image is a Marsis composite, specifically an ESA/ASI/NASA/Univ. of Rome/JPL/Smithsonian derived image of a place on Mars where the the highlands meets the lowlands. The various colors relate to elevations with blue being low and so on. But for the life of me, that blue sure does look like a lake touching a jumbled shore. Perhaps this is an area that many years ago was the shore of a large Martian sea.

Enjoy!

Mataiva Atoll FP - Unwelcomed Treasures

Mataiva Atoll - Google Maps

Mataiva Atoll - Landsat Image S-06-10_2000 (1:50,000)

I have looked at this atoll a few times and each time I decided to not digitize it. The reticulated lagoon represented many hours of digitizing. I knew the finished map would look great, but I just didn't want to do the work. Besides the lagoons near surface coral formations, the outer reef is raised and consequently much of it needed to be digitized into an island polygon layer. A challenge that I took up today. After four hours of digitizing and map composing, I'm finished.

Mataiva Atoll - Raised Reef (WikiMedia Commons)

This photo shows the raised reef of Mataiva Atoll. In the distance is a smaller motu. It makes for a pretty picture, but a digitizing challenge.

Mataiva Atoll - EVS Precision Map (1:50,000)

And here is the finished EVS Precision map. It is an attractive composition as well as an excellent depiction of the atoll.

Now for a little about this atoll and the inhabitants unwelcomed treasures - submerged phosphates. These deposits have been known for some time, but the inhabitants have resisted the mineral extraction of these deposits. Too many Pacific islands are a mess because phosphate extraction was vicisously pursued with little thought to the island's future. Hopefully, the inhabitants of Mataiva Atoll will continue their strong resolve to not exploit these submerged phosphate deposits.

Enjoy!

Hikueru Atoll FP

Hikueru Atoll - Google Maps

Hikueru Atoll - Landsat Image S-07-15_2000 (1:70,000)

There are times Landsat ETM+ island imagery is obscured by clouds. That is when I go to plan ISS or International Space Station imagery. One is not guaranteed that cloud free imagery will be available, but that is where I search for quality imagery.

Hikueru Atoll - ISS Image ISS002-E-8866 (1:70,000)

In the case of Hikueru Atoll, ISS002 snapped some great cloud-free images of Tuamotu atolls. Hikueru Atoll is covered by the above image. Using the above two images I was able to create my finished map of Hikueru.

Hikueru Atoll - Other Precision Map (1:70,000)

This mapping is part of my on going effort to map the islands of the South Pacific at EVS Precision or better. Other Precision is always EVS Precision or better. The map was finished using Marplot mapping software.

Hikueru Atoll is covered by a brief article in Wikipedia. As of the 1988 census, 124 people live on Hikueru. They earn a living from copra, fishing and pearls. The atoll does have an airport, which can be seen in the ISS image, that was built in 2000.

Enjoy!

Data - 1:1,000,000 World Shorelines

I am not against a good resolution world shoreline. In my personal GIS, I have four world shorelines. They are: 1) 1:2,000,000 2) 1:250,000 WVS 3) 1:63,500 NGA PGS 4) 1:1,000,000 VMAP0. They all serve a purpose. I use the 1:2,000,000 for global and multi-country projects. The 1:250,000 WVS is used for most of my preliminary work on islands. For example, to locate individual islands and island group. Since I've loaded NGA PGS vectors, they have become my default layer for small island preliminary digitizing projects. I get to study the island prior to working on it in Global Mapper. Now, I have 1:1,000,000 VMAP0 world shorelines. They will most probably replace much of my use of 1:2,000,000 shorelines.

Why not share the wealth! I constucted this 1:1,000,000 scale world shoreline using VMAP0's shorelines. I simply loaded the boundary layers of the four area files, Europe, North America, South America and Asia, and combined them into a single global layer. I have uploaded this file and will share it with those of you needing a 1:1,000,000 scale world shoreline.

1:1,000,000 World Shoreline

Select the above link and download the file. It is in SHP format.

Enjoy!

How To Digitize Shorelines Using ISS Imagery

My mapping target for the night, Takume Atoll. The Landsat image, S-07-15_2000, looks pretty good. Clouds obscure the northern motus. So how does this intrepid mapper solve this digitizing problem.

First, I checked out DigitalGlobe's imagery in Google Earth. The northern section of the atoll is covered with cloud-free hi-res imagery. Since I am looking to possibly explore commercial opportunities for my EVS precison island maps, DigitalGlobe imagery is a "no go".

I visited the Gateway to Astronaut Photography and poked around to see what imagery was available for this atoll. It turns out during the ISS006 mission, this atoll was photographed. I downloaded both photos and went about putting them together.

I pieced the two images together using Irfanview and ImageForge. I loaded the northern section first and placed the southern section on top of it. I had to do a small stretch to make the southern image fit onto the northern section.

I trimed the modified image and saved it. Now I have to tilt it at the proper angle to better georectify the image.

Using a measuring feature in Global Mapper, I was able to determine that the atoll is at a 42° angle. Now I needed to tilt the image 42°. Irfanview allowed me to tilt the image the requisite degrees.

I used Global Mapper's georectifying module to georeference the tilted image. I selected a rectification routine called Triangulation which requires 5 GCPs. 3 GCPs were selected in the northern section and 2 GCPs were selected in the southern section.

And there is the georectified Takume Atoll ISS image.

I used the ISS image to digitize the cloud covered northern motus. Once they were completed, I tricked the top image (ISS) to complete digitizing the balance of the atoll.

I used a translucency option and converted the ISS image to 70% translucency. This allows the underlying image, primarily their colors, to show through the top image. I used this setup to complete digitizing the remaining shorelines.

Here is the finished northern section of Takume Atoll. All of the cloud covered motus are mapped using ISS imagery. Pretty cool, huh?

Enjoy!

Marokau and Ravahere Atolls - EVS Precision Map, Google Map, Yahoo! Map, MS Live Search Map, and MS MapPoint Map

Marokau and Ravahere Atolls - EVS Precision Map (1:250,000)

I am mapping my way through the Tuamotus, with a goal of having EVS Precision maps for all islands located in the South Pacific. I finished mapping shorelines and reefs for Marokau and Ravahere Atolls. The atolls have a reported population of 50 plus. The folks make a living off of copra, fishing and pearling. The eastern edge of Marokau's long motu has a number of pools, most probably saltwater created from heavy surf during a storm. It sure does make one ponder the tenuous life lived on a 1 to 2 meter high atoll.

Interesting, but not the complete reason for sharing this post. Let's take a look at how the big three internet map moguls handled these tiny jewels.

Marokau and Ravahere Atolls - Google Map (1:800,000)

Google Maps - Their shorelines are DCW (Digital Chart of the World). 1:1,000,000 is as good as it gets with Google Maps. Actually, the above map is at a scale of approximately 1:800,000. That was the closest I could zoom. I've had people tell me these maps are intended for routing and coarse direction finding. I think that is all one could hope for. DCW was a heck of a map during the infancy of the Internet. Now it is a mapping dinosaur, depicting shorelines with a very crude degree of detail.

Marokau and Ravahere Atolls - Yahoo! Map (1:300,000)

At least Yahoo! lets us zoom in to approximately 1:300,000 scale. Their map also includes the atoll names. Nice touch, but still DCW shorelines.

Almost ditto with Yahoo!'s map. MS Virtual Earth included the names of two villages found on these atolls. They neglected to include the names of the atolls, but we do have the villages named.

Marokau and Ravahere Atolls - MS MapPoint Map (1:400,000)

MS MapPoint can be found at a number of sites. It is an MS product that sells for between $250 to $70. At first glance, it looks to be a significant improvement over the DCW derived maps. However, it isn't. It is still a DCW derived map. The motus have a nifty blue ring around them and a reef feature ringing the atoll is identified. The reef feature is standard with any DCW country download. However the nifty blue rings around the motus looks to be a motu enhancer. The names are from NGA Country Files and the bathymetry is DCW standard issue.

This is the data world in action - take free government data, package it and sell it again and again! I acknowledge that TeleAtlas and Navteq should focus their mapping efforts on streets and roads within major cities. That is their cash cow. But to still be using DCW shorelines in many places throughout the world is silly. I'm sure that money dictates their every mapping decision. In this case, map quality should be the overwhelming determinant.

When my maps are consistently of far greater quality than Google, Yahoo! or MicroSoft or of their map providers, Teleatlas and Navteq, something is out of wack . . . and it isn't me and my maps. TeleAtlas and Navteq needs to spend a few bucks to upgrade their shorelines. WVS would be a significant upgrade over their current shorelines. For island shorelines, EVS precision vectors are the only way to go.

Enjoy!

Easter Island - Finally Finished

Easter Island - Other Precision Map (1:100,000)

Yep! Finally finished with this map. I have worked off and on on this map for a year. Back in August 2007 I completed everything but the water features in Rano Kau crater and modifying three minor contours (20-m, 40-m and 60-m). A few months back I got an email from a person wanting to use this map in a publication. That presented two problems. First problem, the map was constructed from DigitalGlobe imagery. First problem solved - I got in touch with my contact at DigitalGlobe and explained the problem. He got back to me with permission to use the map ensuring proper crediting took place. Second problem, had to finish the map. Second problem solved - I went back to work and finished the Rano Kau crater water features and finished modifying the minor contours. Problems solved and map will appear in this person's soon to be published book.

Rano Kau Crater - DigitalGlobe Image from Google Earth

Just thought I would share the DigitalGlobe imagery I used to complete the Rano Kau crater water features. After many hours of small water feature digitizing, I am here to tell you there are lots of little ponds and puddles at the bottom of this crater.

Easter Island - Other Precision Map (1:8,340) - Rano Kau Crater

After finishing, I am satisfied with my completed Easter Island map. Also, I am happy that my map will be used to make a person's book a better one.

How To Map Reef Features at EVS Precision

How To Map Reef Features - EVS Precision Map with Island Polygons (1:95,000)

During the month of May 2008, I digitized approximately 8,000 island polygons scattered throughout the southern Pacific Ocean. All of Papua New Guinea to the Cook Islands were mapped at EVS precision using Landsat ETM+ base imagery. And I got paid for my efforts! The above map is of a stretch of coast along the eastern shore of Bougainville, specifically approaches to Kieta and Anewa Bays. The customer purchasing the vector mapping wanted only shorelines as depicted on Landsat ETM+. All of my digitizing was at scales between 1:25,000 to 1:12,500, pushing the limits of Landsat ETM+.

How To Map Reef Features - Aus 683 Nautical Chart

The above image is an enlargement of a thumbnail chart view provided by the Australian Hydrographic Service. It is intended to show you a rough depiction of the Kiela and Anewa Bays. Nautical charts have always been my inspiration for shoreline mapping. They typically minimize the on-shore details and focus, as you would expect, on the actual shoreline and off-shore features. I wondered if I could use Landsat ETM+ imagery to mirror Aus 683 reef details.

How To Map Reef Features - Landsat and DigitalGlobe Images (1:95,000)

Landsat is not DigitalGlobe. 14.5-meter resolution compared to 1-meter resolution is Minnie Pearl compared to Angelina Jolie. However, if you really work with the "Minnie Pearl" resolution, one can create an accurate, within reason, and pretty good looking map.

How To Map Reef Features - Landsat False Color Image (1:95,000)

Having gained considerable experience at mapping reef features over the last few years, I've developed a reef mapping method. Using Global Mapper's image enhancement features, I trick my Landsat image using an enhancement called "Difference". It creates a consistent series of false colors causing reef features to display more clearly. Using a blue background, the reef features appear as sickly yellow colors.

How To Map Reef Features - EVS Precision Map with Island Polygons and Reefs (1:95,000)

My first pass created reef polygons. I use a layer designation EVS Reef Shallow. Any yellow patch of color is identified as EVS Reef Shallow. I realize that one is able to extract a great deal of subtle reef information, given time. However, my goal is to try and emulate Aus 683's shorelines and reefs. The above map should be my finished product. It isn't.

How To Map Reef Features - EVS Precision Map (1:95,000)

How To Map Reef Features - DigitalGlobe, EVS Precision and Landsat

When one works at scales between 1:25,000 to 1:12,500 other reef features become visible, the white spots at the reef's edge, for instance. They could be sand bars, above water coral or waves. It turns out, when comparing 1-meter imagery of the same area, they are waves - turbulent white water sloshing across a reef shelf. I label these wave features as EVS Reef Awash. I define a reef awash feature as a visible feature typically at the reef's edge. Most often these features are waves. These breaking waves give a fairly consistent signature whether they are sliding across a reef or smacking against a continental shoreline.

My finished EVS precision map of this area now contain reef features - EVS Reef Shallow and EVS Reef Awash. I think they provide important information to all map users. And by the way, it turns out my EVS precision map of Bougainville is far superior to AHS's coverage. They have two charts covering this island. One at 1:300,000 (Aus 399) and the other covering five different areas along the east coast (Aus 683). My EVS precision map covers the entire island and outlying islands, with reefs, at scales between 1:125,000 to 1:50,000.

Enjoy!