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

Thoughts - Wow! I Didn't Know Global Mapper Could Do That or Discoveries at 4:00AM

Arutua Atoll FP - EVS Precision Map (1:170,000) - Upper Image

Arutua Atoll FP - EVS Precision map (1:75,000) - Lower Image

At first glance, except for a simple coordinate grid, use of a slightly different map scale and the addition of other necessary cartographic trappings, my original image of Arutua Atoll (upper) looks like the Arutua Atoll (lower). Although the images are both sized at 500 x 347 pixels, to fit into this web page, the two images are quite different. The upper image is JPG, whereas the lower image is PNG. I have been using PNG format images for my last few posts. Supposedly, they give one a better, sharper image at a much smaller size compared to JPG. Frankly, for what I am doing (posting an image of a vector map) the JPG format seemed to work fine. That is until I discovered my Global Mapper "Wow!".

I love my finished maps and enjoy sharing them with readers that appreciate my work. I believe most readers are often content to view an island image, read the brief article, ponder it and then go their merry way. As it should be. However, for the intrepid few that really want to check out the island map, that take the time to select the island image and view the original sized image in Flickr, have I got a treat for you!

If you select the lower Arutua Atoll image and follow it to Flickr, you will be able to view my original sized image of Arutua Atoll at a scale of 1:75,000. Global Mapper, my primary mapping software, allows me to capture a screen's contents to an image.

Global Mapper Image Capture

This is not a new discovery, as I have been using this option for years. But this morning I decided to changed the image size from a default of 1264 x 875 pixels to 2578 x 1750 pixels. This change transformed my 1:150,000 scaled island image into a 1:75,000 scaled island image. My original 1:150,000 scaled image will print on a standard 8.5" x 11" sheet of paper. To print my 1:75,000 scaled image would require a 21" x 14" paper. Within Flickr, the reader can view an image that more nearly displays the island at it's EVS precision viewing limits (between 1:75,000 to 1:50,000). Using Global Mapper to create my images, I am able to generate two additional files that allows one to view the island image with appropriate lat/lons (.pngw and .prj files).

My bottom line discovery - by varying Global Mapper's screen image capture size, I am able to quickly generate EVS precision island maps at meaningful viewing scales. And that's my 4:00 AM "Wow!"

Enjoy!

Arutua Atoll FP - Beautiful Atoll and Long Mapping Hours

Arutua Atoll FP - Base Image From Landsat S-06-15_2000 (1:170,000)

Arutua Atoll FP - EVS Precision Map From Landsat S-06-15_2000 (1:170,000)

According to a Wikipedia entry, Arutua Atoll has a population of 500 with the majority living in Rautini Village. These hearty souls earn their living off of copra, fishing and pearling.They do have a small airfield located on their island.

Let's talk about what went into the construction of this map. I worked in excess of 12-hours on this map over a period of 4-days. The excessive amount of time devoted to this project had to do with the size of the atoll (31-km by 24-km). This map consists of 812 unique features. The majority of these unique features are motus (small island polygons) and coral heads within the lagoon. The trick to digitizing this atoll is determination, patience and cloud-free imagery. I initially worked off of the Landsat ETM+ mosaic, digitizing at scales between 1:25,000 to 1:12,5000. The digitizing process was tedious and tiring, but the final map looks great.

Arutua Atoll FP - Rautini Village From DigitalGlobe Image (1:6,800)

Arutua Atoll FP - Rautini Village in Other Precision Map From DigitalGlobe Image (1:6800)

Just for the fun of it, I digitized Rautini village using a DigitalGlobe image from Google Earth as my base image. The village took about 2-hours to complete. I added the road layer as a bonus feature.

All in all, I am pleased with this series of maps and I hope you find them interesting.

Enjoy!