How to Map Caldey Island Using Windows Live Local Imagery
***First off, most of these images come from MS Windows Live Local (WLL) and Getmapping plc. If I am in violation of any copyright infringement issue, I will swiftly rectify the problem by removing the images. By the way, my maps are not intended for commercial purposes. I just like to make maps.***
With that said, let's get started!
Some months back I posted a Landsat image and EVS map of Caldey Island UK. I felt the digitizing was as good as I could extract from the Landsat image. That is until I checked out WLL's image of the island. More specifically, the Getmapping plc image of the island. It has to be 1-meter resolution or better. The imagery is exquisite. Just the kind of imagery that would tempt me to redigitize a shoreline and enhance a map. So I did.
Let's begin with my original Landsat image.
Landsat ETM+ 2000 Imagery of Caldey Island (N-30-50_2000)
Not bad, actually it is very good resolution. It is cloud-free and the shoreline is clearly discernible. It is a good image from which I am able to create an EVS precision shoreline. Of course there is better resolution, but it is not readily available. That is, not until WLL and Getmapping plc teamed up.
WLL Imagery of Caldey Island
Now this is high resolution imagery. I looked at the tools available in WLL and sure enough the program has a path creation tool. Actually, it is more like a path drawing tool that pales in comparison to Google Earth's (GE) path tool. Whereas GE's path tool records vertices as lat/lons, the WLL tool doesn't. At least, I couldn't easily figure it out. GE let's you save your finished path as a KML file, that can easily be converted into vector files for use in many mapping programs, WLL's path tool just made a thick line on top of the image. Not very useful for a map maker.
So, I did what any respectable GIS geek would do, I worked with the WLL imagery to make it fit into my mapping program. Frequent readers know that I primarily use two different mapping programs: Global Mapper and Marplot. Both offer me the ability to create EVS precision maps easily and cost-effectively. I can georectify quickly using Marplot, so that became my mapping program for this project.
WLL Modified Images
This Flickr slideshow begins with my first modified image of Caldey Island, an overview of the island. The next five images are of detailed sections at a scale of 1:200-meters from which I could digitize the shoreline with a high degree of precision.
WLL Modified Images in Marplot - Ready to Digitize Shorelines
I took these images and stitched them together in Marplot and ended up with the above georectified image. How was it georectified? I aligned the images using my previous EVS shoreline of the island as a guide. No! It is not as precise as other methods, but for the purposes of this exercise and in the absence of quality ground control points, this will do. I worked at 1:5,000 and created five distinct layers of information in addition to my new shoreline.
Caldey Island - Marplot Map (1:12,500)
My additional layers of information are the result of a quick photo interpretation of the base imagery. If this map were to be produced for commercial use a more careful, systematic study would have generated a number of other useful layers of information.
WLL has some great imagery that I would love to be able to work with in my EVS mapping. However, it requires a great deal of image manipulation before a mapmaker can make a map.
Alex Daley, Technical Evangelist of Microsoft's Virtual Earth Business Unit, please evangelize the enhancement of WLL to include robust map-making tools. The GIS geeks of the world would be most appreciative.
Enjoy!
