Enhanced Vector Shorelines of the World - One Island, One Coastline, One River and One Lake at a time.
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!
Thursday, February 14, 2008
Guadalupe Island MX - A Cloud-Free Image
6 x 16 Grid
Using DigitalGlobe imagery from Google Earth, I selected 96 carefully sequenced screenshots, each at a scale of 1:15,000. From these screenshots I was able to create this complete 4.56MB standalone cloud-free image of Guadalupe Island MX. The 6 x 16 grid shows how the screenshots were arranged to complete the mosaiced image.
A Cloud-Free Image of Guadalupe Island, MX (1:15,000)
The experienced reader knows all one really needs to do is log into Google Earth, center on Guadalupe Island and zoom onto and about the island. So, it is fair to ponder, "So what!"
My image is portable. I load my DigitalGlobe imagery taken from Google Earth, into my mapping software, Global Mapper, and explore the island at my leisure. I made sure to credit both sources, using their standard image trademarks (see very bottom of image).
Guadalupe Island - Cypress Groves (1-25,000)
Now, I can zoom above the cypress groves located in the upper portions of the island...
Guadalupe Island - Southern Portion (1-12,500)
Or head south to view the area of one of two semi-permanent villages located on the island.
This is about counting trees. Not just any trees, but Critically Endangered Cupressus Guadalupenses trees, according to the IUCN, Conifers Division. And this is about counting trees using Digital Globe imagery found in Google Earth. And, finally, this is about counting trees and placing their location and characteristics into a database that feeds into a vector map of Guadalupe Island.
Counting Cypress Trees On Guadalupe Island
So let's get started.
Slide-1) The first image shows the entire island. The island is 34-kms by 11-kms and is a high island with elevations in excess of 1200-meters. The lower elevations are desert like, whereas the higher elevations receive abundant moisture from rain and frequent fog. It is in these higher elevations that we find the Cupressus Guadalupenses. This post will focus on two of the larger groves of Cypress trees located above and to the west of the island's center.
Slide-2) Here are the two groves. The southern grove, at 1,440,000 sq meters, is twice as large as the northern grove, at 650,000 sq meters.
Slide-3) The area calculations are derived from my vector map of the island. Using DG imagery and Marplot mapping software, I digitized and mapped the shoreline and the stands of Cypress trees I could easily identify.
Slides-4,5 and 6) Let us look at the southern grove at a scale of 1:12,500. An accurate area boundary can be digitized at this level of resolution. Slide 6 is a ground-level view of the Cypress grove from a distance of perhaps 1-km.
Slides 7 and 8) These images display the benefit of hi-res DG imagery when it comes to flora identification and inventory. Single trees are easily discernable. To the trained eye, individual trees could be identified. Their color and foliage would permit health assessment. Dead trees, both standing and toppled. could be inventoried as well.
Slides 9 and 10) The northern grove has a greater density of trees. The same assessments could be conducted here as well as in the southern grove.
Currently, using Marplot, my name field for each tree would contain data unique to that specific tree. The database creation is a chore, but done once, anyone could maintain it. This sort of database, anchored to a vector map, would be invaluable to all of those with an interest in the preservation of these Critically Endangered trees.
I have wanted to map this island for quite some time. Landsat imagery was full of clouds, not good to map details of both shoreline and the island proper. I located some ISS imagery that was relatively clear. The resolution was crude compared to Landsat. Finally Google Earth managed to snag some 1-meter resolution Digital Globe imagery. I had the perfect image, now I just needed time, like Christmas vacation. I have worked on this map and the various layers for about 10-hours. The shoreline is as good as it gets. The northern end of the island is cloud obscured and I had to use ISS imagery to approximate the shoreline. However, the bulk of the shoreline is crystal clear.
Mapping in Google Earth is a challenge. In Marplot it is easy to create multiple features within the same layer (i.e., five Cypress Tree Groves). In GE, each feature stands by itself. I had to create five separate files for each grove of trees. The problem comes when you have many features (i.e., small islets ringing this island). I had to create 13 separate KML packets. Each had to be handled separately to reformat so that they could drop into Marplot.
This island was ravaged by a variety of feral animals, goats and rabbits primarily. The goats eat anything and everything. They were eating the Cypress tree seedlings. They were destroying this unique ecosystem. The Mexican government and US agencies have worked cooperatively to eradicate these feral pests. I noticed that the large stands of Cypress trees are ringed by fences. Reportedly, the goats are almost completely gone. The fragile ecosystem is recovering.
Not in our lifetime, but in our children's children, they will be able to visit a verdant forest that will cover the entire higher elevation of this island. They will stay in a swank lodge and for fun take long hikes. No, not in our lifetime, but perhaps our children's children will experience it.
Enjoy!
PS - The SRTM data was great, so I created 100-m interval contours. Now the map image contains the EVS Contours layer. And now I am finished with Guadalupe Island.
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.
