Tuesday, November 24, 2009

Mapping Grenadines MarSIS with Google Earth

I haven't written in awhile nor kept this blog updated on my project work. I've been busily working away at CERMES on a decent first draft of of the Grenadines MarSIS Google Earth file that I discussed previously on my other blog. Though I have a post that says I got the geodata back on September, I really got the final, final data about two weeks before a workshop trip, launching the file that I'm going to explain in this post.

I went with MarSIS project leader and GIS data collector, Kim Baldwin, on a presentation tour to three public workshops the week of Nov 9 to 13, 2009, and you can read about that trip here. It was amazing. She presented the GIS work she's done and I showed the participants how to use Google Earth and how to use the MarSIS data in Google Earth. The MarSIS project is a marine-based resources project for the Grenadine Islands, between (but not including) the islands of St. Vincent and Grenada in the Caribbean. That's all about the workshops for now.

As a result of the workshops, we got terrific feedback on the usability and functionality of the project KML. There were some things that were not so clear, too. We are not ready to show or give out the final version of the KML. Once the file is ready, it will be launched on the MarSIS web site as a Google Earth API plug-in and I'll blog about it. The plan for this user-ready final product is February 2010.

Above, is a list of the subsets of data layers found in the MarSIS project. I basically took Kim's Geodatabase feature layers and exported them using the free ArcScript Export to KML or the not free Xtools Pro. There was some iteration involved but I used one for one thing and one for another. It was pretty painless.

The two screen captures below show some of the results of the export process. There's no legend which is something I will work on in the coming months.

Above, shows the shallow water habitat polygons, locations of whelks, and sea turtle nesting beaches around and near Mayreau Island.

And this screen capture above shows Space-Use Patterns (pink font) and Marine Resource Users (blue font) layers turned on for the area surrounding Union Island.

Kim has a lot of underwater photographs that she's used to identify habitat type and map the sea floor. Above is an example of what one of the photos looks like in the KML. I also blogged about the preliminary results on another blog I have. She also took a lot of underwater video for the deeper areas for the same reason, to map the sea floor. The videos will be included, but for the recent presentations, we used a representative single frame as a jpeg. There are nearly 400 locations and images that are in the KML. Here is how to put lot's of photos into KML.

Use Spreadsheet Mapper 2.0 You are given a choice of six placemarks templates that you can customize if you wish. You use a template built in a Google Doc spreadsheet that you then create a network link so that you can "automagically" build the placemarks for your georeferenced photos. Here is the Google Doc template. When you start to load you're information, you should prepare a table with latitude and longitude of each shot, URL to each photo (or video), some metadata perhaps (i.e., "The habitat shown in the photograph is classified as Sea Grass, the fisher classification is Sea Grass and the research description is: Rubble, w/macroalgae & syrigodium. The depth at this location is 29 feet.") which is semi-easily obtained from the shapefile table with a little concatenation. Link to the project page or blog. Then Publish your Google Doc and you're live!

Finally, I made a KML Screen Overlay described at the Google Earth blog with the MarSIS project logo. You can see it in the screen captures.

The plan for taking this MarSIS KML to a final version in the next couple of months is: 1) create legends for the polygonal habitat maps, 2) figure out how to use SuperOverlay to slice up and load a nautical map of the Grenadines (shown as an empty folder above called "Imagery/Maps"), 3) fix some of the metadata that didn't export properly from the geodatabase (i.e., island = 6 should be island = Palm Island), 4) figure out how to get rid of snippets, and 5) embed the map into the MarSIS web page using Google Earth API.

Note: Here is the final installment on steps I took to create this KMZ file.