Data - WVS/GSHHS Global Shorelines

WVS/GSHHS - Pacific Centered

Over three years ago I learned of the GSHHS vector map file of the world shorelines. The data is reworked WVS, which allows one to construct a 1:250,000 world map. My problem was the only mapping software I used at the time was Marplot. Unfortunately, Marplot is quite limited in files that can be imported into it. So I held this data until I purchased software that could read and display the data. Along came Global Mapper.

WVS/GSHHS - Atlantic Centered

WVS/GSHHS - Atlantic Centered without Inland Water Features

I did not want to work with a Pacific-centered map. The version of the GSHHS only came as a Pacific-centered map. I prefer working with Atlantic-centered map. So I asked Mike, at Global Mapper, if he could modify the file into an Atlantic-centered map file. He said sure, and he did it that same day. This map I could use. I loaded the files into Marplot and used them extensively as a primary global shoreline. But somebody stuffed a batch of water features into this database. So, for the past 4-hours I carefully removed, named and relayered these inland water features.

GSHHS - Atlantic Centered with Inland Water Features Modified

WVS/GSHHS - Atlantic Centered with Inland Water Features; Detail Caspian Sea

WVS/GSHHS - Atlantic Centered with Inland Water Features and Streams; Detail Caspian Sea

After removing these inland water features from the WVS/GSHHS data set, I converted them into polygons and placed them back into the WVS/GSHHS map. I then inserted the VMap0 stream/river/intermittent stream line file which I had extracted from VMap earlier. The final map above shows the Caspian Sea with all of the streams that feed into it.

What prompted me to go through this exercise, was the four or five readers every day that come to this website looking for world shorelines. The WVS/GSHHS data is excellent. It allows one to plot a highly accurate view of the world. Using the NGDC Coastline Extractor one can download various layers of boundary information, along with the global shorelines.

It turns out that the GSHHS data is now available as an Atlantic-centered map with all of the inland water features bundled with the primary shoreline data as additional layers of information. And the price is FREE!

I really like the WVS/GSHHS data. Once loaded, it gives one an excellent shoreline resource. What you need after loading the WVS/GSHHS data is the VMap0 data layers (Roads, Railroads, Contours, Depth Contours, streams, lakes, etc.). Then you have a very slick map to work with.

Enjoy!

Thoughts - Sherbro Island SL and a Mystery Landform

Sierra Leone and Sherbro Island

Sherbro Island - Landsat N-28-05_2000 (1:275,000)

Sherbro Island is located in the center of the first image. As can be seen in the next image, it is a fairly large river-mouth island, which typically results in large portions of the island being water-saturated with highly dynamic shorelines. That is the case for much of this island. However there are other parts of the island that are of a more permanent nature. For example, the southwestern ocean-edge of the island is uplifted and less subject to the whims of the weather and river dynamics.

Sherbro Island - EVS Marplot Map (1:275,000)

This project has resulted in long hours of water-feature digitizing. Because the vectors were created using Landsat imagery, the digitizing task was simplified. However it has been a chore getting the project to this point. I still have a number of landforms to digitize (swamps, mudflats, sandbars, etc.).

Sherbro Island - What is this landform?

I think this landform is a series of old shorelines. The zoomed images show trails crisscrossing them leading to a from the ocean shore. When I first saw this feature, I thought it might be areas of cultivation. After studying the DigitalGlobe image from Google Earth of this landform, it doesn't appear to be cultivated areas.

My question to EVS Islands readers, "What is this landform?". Thanks in advance.

View Sherbro Island on Google Maps

Enjoy!

Thoughts - Easter Island; Almost Done

Easter Island - EEVS Map (1-100,000)

As the title so aptly states, "Almost Done." I still have a few more features on the island to digitize and then I need to add the "fancy" stuff using ImageForge, like titles, lat/lon, north arrow, credits, legend and feature names. Stay tuned. This should be finished within the next few days.

Enjoy!

Thoughts - Easter Island Road Layer

Easter Island - EEVS Map Roads (1:100,000)

Easter Island - EEVS Map Detail Hanga Roa Village Roads (1:6,250)

It is 8:30 AM and I have finished the Easter Island road layer. The village, Hanga Roa, has the majority of the roads found on the island. The image resolution I am using does not show hi-res details outside of Hanga Roa. I will compare my digitized road network with the road network found on the DigitalGlobe image in Google Earth.

Let's call this road layer my preliminary effort. I have some verification work remaining and road segment determination to complete before I finalize this layer.

Easter Island - EEVS Map Vegetation and Roads (1:100,000)

This is the extent of my Easter Island mapping project; shoreline with off-lying rocks, vegetation (trees) and roads. I have invested about 14-hours of labor to create the current view of Easter Island. My next layer will be another vegetation layer. It will include all other low-lying vegetation.

Enjoy!

Thoughts - Easter Island Vegetation Layer

Easter Island - EEVS Map Vegetation (1:100,000)

Easter Island - EEVS Map; Detail Hanga Roa Village with Vegetation (1-6250)

I am continuing work on Easter Island. Just having finished a vegetation layer that shows distribution of trees, I decided it was time to post a progress report with a couple of observations.

First, about the trees. In the movies Rapa Nui the inhabitants destroyed the forest to transport their mega-moais. What I have learned from this current mapping exercise is that trees are growing on Easter Island. There are a number of large tracts of trees and many individual trees are scattered about the village of Hanga Roa.

Second, What about the detail? The second map is a zoom of the southern portion of the village of Hanga Roa. The scale is 1:6,250. This is possible because I am using a DigitalGlobe image found in Google Earth as my base image. I was able to map shoreline details (offshore rocks above water and awash) that have, most likely, never been mapped before, primarily, because of the availability of hi-res imagery. The final map will distinguish between rocks awash and rocks above water. For now they are part of the Land-Island layer.

My next layer will be the roads, paths and airfield. I'll post it when I've finished the next layer. So far, this is one of my most complex mapping projects consisting of lots and lots of vectors to show two layers of information.

Enjoy!

Thoughts - Easter Island Shoreline 12,615 Vectors Later

Easter Island - EEVS Map (1:100,000)

This is a continuation of my previous post. EEVS quality mapping requires lots of vectors. As the title states, at this preliminary stage, 12,615 vectors were digitized by me to create this shoreline. I worked in Google Earth using the path tool. The first pass was relatively fast taking about 6-hours. The final pass, the fine tune, took another 3-hours. I will have to work on this shoreline in Global Mapper to finish it. Two parts of the island, the north and western edges will be digitized using Landsat as they are not included in the Google Earth map. I have loads of work to do on this map digitizing layers of information.

My point is that DG imagery is great, but to execute a quality shoreline, one must do lots of digitizing.

Enjoy!

Thoughts - Landsat = EVS / DigitalGlobe = EEVS

Groupe Acteon - Landsat Image S-08-20_2000 (1:200,000)

Groupe Acteon - EVS Map (1:200,000)

Ignorance is bliss. or so they say.

Two years ago I was thrilled to make a map using Landsat ETM+ as my base imagery. These Enhanced Vector Shoreline (EVS) maps are some of the most detailed, consistently formatted and visually appealing maps freely available to any and all. I have mapped islands, employing rigorous and proven procedures, ensuring that the stage, which consists of Landsat images and EVS maps, is clearly rendered so that their individual stories can be told in their unique geographical context, as evidenced by the Groupe Acteon Landsat image and EVS map above.

Groupe Acteon - DigitalGlobe Image in Google Earth (1:200,000)

Ignornace is bliss. until you know what you know.

What used to be, in Google Earth (GE), a smudge of green suggesting land, is now DigitalGlobe's (DG) high resolution imagery. GE and DG, working together, gives us exquisite high resolution views of islands throughout the world, including Groupe Acteon. Where Landsat ETM+ used to rule, not so anymore. The new ruler is DG using GE's mapping platform. DG's high resolution imagery costs big bucks, unless you are a mega-funded government agency. Big bucks that us little folks will never be able to afford. Working with GE, this imagery is now ours to view. Oh, yes, and ours to use as base imagery to create non-commerical maps (just make sure you credit sources).

Last night, I finally faced up to a harsh reality - EVS quality pales in comparison to Extremely Enhanced Vector Shorelines (EEVS) quality which comes from DG's high resolution imagery. The improvement in shoreline resolution is dramatic. What Landsat suggests, DG clearly shows. Striving to produce the best map, I am faced with a genuine dilemma, to redo EVS quality maps when EEVS quality is available, or not. I want to say "Not.", but I realize "Redo" is, most often, the correct response. Let me explain. The islands I map are very small chunks of real estate. Consequently, little digitizing inaccuracies become very big mapping inaccuracies. Take a look at the following.

Matureivavo Atoll - Landsat Image S-08-20_2000 (1:20,000)

Matureivavo Atoll - EVS Map (1:20,000)

Digitizing from the Landsat image, I was able to create the above EVS map of Matureivavo Atoll. Considering what Landsat was able to show, in my opinion, the resulting map was a solid effort. However, Landsat, at 14.5 meters per pixel is not DG HiRes at 1 meter per pixel.

Matureivavo Atoll - DigitalGlobe Image from Google Earth (1:20,000)

The EEVS map I will create, using the above DG imagery, will be considerably different than my Landsat effort, as it should be. I will map the majority of this complex reef as being water inundated. The small sand bars will be mapped as above water features. The sparse vegetation layer along this reef will be designated as underwater vegetation and be mapped accordingly. The resulting shoreline of this section of reef will be considerably different. Much of the original EVS quality shoreline will now be mapped as an underwater feature. I will make many different mapping decisions based on this high quality image, resulting in an EEVS quality map.

The horns of my dilemma - Is there room for both EVS and EEVS quality mapping?

Obviously, when Landsat imagery is the only available imagery, EVS rules. However, when DG imagery is available for the same area, EEVS rules. As I compare my EVS maps to DG's EEVS quality imagery and I find the EVS details are of sufficient quality to qualify as an accurate map, it will remain. If I compare an EVS map to DG's EEVS quality imagery and find it lacking in detail and accuracy, I will redo it.

Enjoy!