Thoughts - Continuing Yesterday's "Wow"!

Arutua Atoll - Four EVS Precison Layers Loaded into Google Earth

A reader of EVS Islands suggested that I load my island maps into Google Earth. He had taken the Flickr image of Arutua Atoll and created a Google Earth overlay. He did all of this work by manually matching the EVS image to the GE base image. After viewing his work I had another Wow! moment. It turns out Global Mapper creates KML/KMZ files. I have generated GE KML/KMZ overlays previously, but I thought I would try something different. Using the Arutua Atoll vectors, I created a separate overlay for each vector layer using PNG image format's transparency function. I began with my Reef Shallow and the ocean as my first layer without any color transparency.

Arutua Atoll - Base Layer Reef Shallow with Ocean (1:75,000)

The other three layers would rest atop this base layer. The next three layers were EVS Island Polygons, Vegetation and Inland Water. I made the blue ocean the transparent color for these layers. This resulted in overlays consists of 12 georectified tiles per layer neatly positioning an EVS precision island map into GE.

Arutua Atoll - Four Layers Loaded into Google Earth (1:75,000)

Loading these four layers in proper order (Reef Shallow, EVS Island Polygons, Vegetation and Inland Water) one is able to switch layers on and off to view this atoll from a number of unique perspectives. Pretty cool!

Arutua Atoll - Four Layers in KMZ Files

I have posted the four layers and you are welcome to download them and try them out. They are at the following links: Reef Shallow, EVS Island Polygons, Vegetation and Inland Water. Remember to load Reef Shallow first, EVS Island Polygons second, Vegetation third and Inland Water last. The map is at a scale of 1:75,000. That allows you to view the map at the 4.00 kilometer center read using GE's scale bar. If you take the map below that scale it begins to get ugly fast (blurred lines and colors). Hope you find it interesting. Comments are appreciated, especially KML/KMZ types. I am certain there must be a way to load all layers within one KML/KMZ packet and still be able to retain the ability to pile layers on top of each other and exercise control over whether a layer is on or off. Thanks in advance.

Enjoy

How To Quickly, Accurately and Easily Overlay a Georectified Image into Google Earth Using Global Mapper v9.0

Very Large Kingman Reef - Vector Shoreline View from Google Earth

This is the map that got me started on the mysterious very large Kingman Reef. The sides of the reef are depicted as 140-kms in length. Whereas Kingman Reef is actually a 1/10th of that size. Somebody misdigitized the reef, most probably in the early days of government produced vector maps. Oh, well, that's another story for another time. Meanwhile, let's talk about creating a nifty georectified image overlay and placing it into Google Earth (GE).

Using Global Mapper v9.0 (GM), the process to take an image, georectify it, export it as a KML/KMZ formated file and finally load it into GE is, as my title promises, quick, accurate and easy. How quick - about 2 to 5 minutes, depending on the complexity of the georectifying needed. How accurate - as accurate as you are able to georectify your image against known coordinates. How easy - even a caveman could do it. (I really do dislike that commercial, but it works here.)

Georectify Image

Step 1 - Georectifying an image using GM's process, lets you compare known coordinates (my previously constructed vector files of Kingman Reef) to my image (DigitalGlobe preview image composite of Kingman Reef). I typically create 3+ Ground Control Points (Affine). The GM windows allow for zooming to enable extremely precise georectifying of an image.

Georectified Image

Step 2 - Admire your work! If the image is whacked, you can go back into the georectifying process and fix it. I am an old pro at this, so my images typically line up just fine with my original vector files.

Export Georectified Image as KML/KMZ File

Step 3 - Select File option and Export Raster and Elevation Data. You are given a list of export options. Select Export KML/KMZ.

Format Your Image KML/KMZ File

Step 4 - My georectified image of Kingman Reef is small and is the only image loaded into my work area, so when it comes to KML/KMZ formatting options, I stick with default choices. If this were a very large image (many MBs), I would be able to grid it into manageable file sizes and load each one into GE. I use the KMZ file format. The zipped image and geocoding data take up much less space and load fast into GE.

Name and Save Your KML/KMZ File

Step 5 - Name your file and save it.

Kingman Reef - Landsat ETM+ Image from Google Earth

Double Click File and Enjoy Your Georectified Image in Google Earth

Step 6 - Now for the fun part. (Make sure you have GE loaded into your computer.) Double click your newly created Kingman Reef KMZ file, pause and then admire your work in GE. If you want to share your image overlay with the world, sign into GE and share away. If you just want to admire your handiwork, admire away!

Like I promised - using Global Mapper v9.0, the process to georectify, export and load an image into GE is quick, accurate and easy. Give it a try.

Enjoy!