The above map shows some of my completed island mapping projects. Each icon contains the name of the primary island associated with the project and a link to the post. Once all of my projects are posted, the map will be covered with icons. To productively use the map, zoom into a region of interest. Then select an icon.
Each of my maps is constructed of numerous layers of information. All of the layers are vector files. I will make these files available upon request. You are free to use them with certain restrictions - 1) Don't sell them. You can use them on research projects, post them to your website or things of that nature. If you aren't sure about the use of my maps, drop me a line and we can discuss your idea. 2) Give me credit when you use my vectors or images of my maps. Credit them to Peter Minton @ EVS-Islands
If I have the island vector file(s) and based upon your need, I will make them available. Images of my maps are yours to download and use, with the above restrictions applicable. Enjoy!
Reao Atoll - ISS004-E-12987, 12988, 12989 Images (1:100,000)
Reao Atoll - Other Precision Map - Source ISS004 Images (1:100,000)
This is my finished shoreline map of Reao Atoll FP. The imagery covering this atoll is of sufficient detail that other layers of information can be digitized, if I wish. For now I just want to complete shorelines within the Tuamotus at EVS precision or better.
Enjoy!
Labels: atoll, EVS Precision, ISS Image, Pacific Ocean, Polynesia
Zoom In to See Pukaruha and Reao Atolls
Reao Atoll FP - ISS004-E-12987, 12988, 12989 Images Modified (1:75,000)
For whatever reason Landsat ETM+ does not have a mosaic that covers Reao Atoll. Google Earth has Landsat imagery, but no imagery for this area at the NASA site where I download my Landsat ETM+'s. As I am making all of my maps without using DigitalGlobe imagery, because one day I might want to sell my shorelines, I must locate other imagery sources. The International Space Station (ISS) is a source of sometimes excellent imagery. And, in fact, ISS004 has 3 cloud-free, highly detailed images covering Reao Atoll, my current target project.
I downloaded, modified their sizes, constructed a "whole atoll" mosaic, rotated the image to align it with my base island shoreline vectors (NGA PGS vectors) and georectified this image using 7 GCPs.
Reao Atoll FP - Other Precision Mapping on ISS Images - Finished Motus (1:40,000)
Reao Atoll FP - Other Precision Mapping - Finished Motus (1:40,000)
Once I had a georectified image, my digitizing could proceed. I decided to map motus first, thus the title of this post. Motu mapping is quick, repetitive and gives one a sense of completion. Each motu is actually a small island. Reao Atoll will ultimately be made up of a 100 or more islands. The two above images show the results of about 2-hours worth of digitizing. I always strive for EVS precision, Landsat ETM+ resolution or better. This imagery allows me to exceed EVS precision. For mapping quality purposes, I label it as Other precision and label it's Source attribute as ISS-Hi Res. I have completed 58 Other precision island polygons. Let's look at the challenges one encounters as they map motus.
Reao Atoll FP - Other Precision - Digitizing Motu (1:10,000)
First, I am working at 1:10,000 scale. At this scale, I am able to maintain sharp feature clarity. In addition, this resolution allows me to make consistent shoreline determinations that will work with the scale of my finished map, between 1:50,000 to 1:25,000. My mapped shorelines consist of actual or suspected (based on color) above-water features. Sounds easy enough to consistently identify, but it isn't. After mapping a few thousand motus, I have learned to make a color(s) to shoreline decision and rigourously adhere to that definition. In imagery, color is god.
In the Reao Atoll image, the motu shorelines are identified as a white sand color. Having studied enough hi-res 1-meter imagery of reefs and motus, I know that between motus are features called hoas. These serve as channels allowing water to flow in and out of the lagoon. Eventually, these hoas fill up with coral rubble and sand, vegetation takes root and motus join motus to form a continuous land ring around a lagoon. Given enough time, the lagoon quite often fills in and, sea level cooperating, a flat island forms where an atoll once stood. Using my white sand color as my motu shoreline, I began digitizing.
Reao Atoll FP - Other Precision Mapping - Finished Motu (1:10,000)
If I do a good job, my project consists of a series of motu shorelines. The digitizing is monotonous, eye-straining and lately, my feet hurt because my chair is uncomfortable. But the finished map is what I work for. I'll share it with you when I've finished. Until then...
Enjoy!
Labels: atoll, DigitalGlobe, digitizing, Global Mapper, ISS Image, Landsat ETM+, motu
Yadua Taba Island - Landsat S-60-15_2000 (1:12,500)
Yadua Taba Island - EVS Precision Map (1:12,500)
As I was mapping this island, I kept repeating the Fred Flintstone saying "Yaba Daba Do". That was what Yadua Taba did to me. Now what it does for iguanas is something else. Yadua Taba is home sweet home to the few remaining Fijian Crested Iguanas. It is the hope of the Fijian Crested Iguana Project to enable the few remaining iguanas to survive. Not just survive, but perhaps to thrive.
Fijian Crested Iguana (from Reuters)
"A Fijian Crested Iguana sits on the head of a statue of a Komodo Dragon at Taronga Zoo in Sydney during an announcement of a funding boost for their conservation June 19, 2008. Only a few wild populations remain of the endangered iguana which is found on a several Fijian islands. The species faces possible extinction due to habitat destruction and competition from introduced species."
Enjoy!
Labels: EVS Precision, Fiji, Fijian Crested Iguana, Pacific Ocean
Raivava'e Atoll - EVS Precision Map on Landsat S-06-20_2000 (1-55,000)
As most of my regular readers know, the bulk of my mapping work is derived from Landsat ETM+. My primary reason for using Landsat ETM+ as base imagery is consistency of product. Typically, anywhere on earth this imagery is freely available, virtually cloud-free and consistently resolved to 14.5-meters per pixel. Great for my worldwide island mapping work. Plus, there are minimal copyright issues when using this imagery. All that is asked is that you credit the source imagery. Did I say "virtually cloud-free"? That is everywhere but in humid climates, in other words in and around islands. Oh, well, it is merely a challenge that the accomplished mapper learns to work around.
The above image is an example of cloud-obscured island imagery. Most of Raivava'e Atoll is visible, but those areas not visible are significant. How does one resolve these areas using copyright-free data (credit source data)? If I am unable to secure Landsat 1990 imagery, which quite often enables one to resolve cloud-obscured areas, I go to Shuttle photography. Specifically, searching for ISS (International Space Station) imagery.
Raivava'e Atoll - EVS Precision Map on ISD_ISS001-375-13 Modified (1-55,000)
Raivava'e Atoll has two images that show the atoll with virtually no clouds. These images are sufficiently large enough that one is able to zoom into and digitize features. First, however, the ISS image must be georectified. Global Mapper allows me to georectify ISS imagery using my Landsat base imagery. In georectifying this ISS image, I used 7 GCP's to ensure the ISS image lay precisely on top of the Landsat base image.
Raivava'e Atoll Outlying Motus - EVS Precision Map on Landsat S-06-20_2000 (1-10,000)
Raivava'e Atoll Outlying Motus - EVS Precision Map on ISD_ISS001-375-13 Modified (1-10,000)
Beginning with the cloud-obscured Landsat image above, I digitized as much of the atoll as possible. The cloud-obscured portions were identified and designated for further work. Visiting Shuttle photography, I found 2 cloud-free images of Raivava'e Atoll. I selected ISD_ISS001-375-13 as the better of the two images. I rotated it and cropped to the atoll. Using this modified ISS image, I was able to complete digitizing the cloud-obscured shoreline. When all else fails, I use WVS shorelines. They are crude compared to EVS precision, but they work.
I use red shorelines to designate EVS precision derived from Landsat base imagery. The green shorelines are designated as Other precision. The source for all Other precision shorelines in my Raivava'e Atoll map is the ISS imagery.
My EVS precision island map of Raivava'e Atoll is complete and I was able to digitize all shorelines in spite of clouds. Pretty cool, huh?
Enjoy!
Labels: EVS Precision, ISS Image, Landsat ETM+, WVS
Trial Download Global Mapper v9
A moderately priced, easy-to-use GIS package, which I use to load, view and work with Landsat ETM+ imagery from which I digitize layers of information for my island maps.
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