The above map shows some of my completed island mapping projects. Each icon contains the name of the primary island associated with the project and a link to the post. Once all of my projects are posted, the map will be covered with icons. To productively use the map, zoom into a region of interest. Then select an icon.

Each of my maps is constructed of numerous layers of information. All of the layers are vector files. I will make these files available upon request. You are free to use them with certain restrictions - 1) Don't sell them. You can use them on research projects, post them to your website or things of that nature. If you aren't sure about the use of my maps, drop me a line and we can discuss your idea. 2) Give me credit when you use my vectors or images of my maps. Credit them to Peter Minton @ EVS-Islands

If I have the island vector file(s) and based upon your need, I will make them available. Images of my maps are yours to download and use, with the above restrictions applicable. Enjoy!

Saturday, November 25, 2006

Thoughts - Creating Contours From SRTM Data Using Global Mapper

Eiao Island FP

Eiao Island - SRTM/DEM With Contours

Eiao Island FP - Contours (50-meters)

Eiao Island - Contours 50-Meter Intervals

This was going to be a "How To" post, but I am not ready to tell you "How To" yet. I am still figuring all of the intricacies that apply to creating contours from Global Mapper. Needless to say, it is a fairly simple process. Load the SRTM DEM/HGT file, determine contour criteria, select "Create Contours" from the File Menu and you have created a series of contours.

Obviously, the contours are only as good as the underlying data (SRTM).  As I work more with the data and how it foots with Landsat and Google Earth 1-Meter Imagery, I will gain greater confidence in creating a new layer of information to be included with some of my high islands.

I think it could be a great addition to my EVS Islands. Just have to wait and see.

Enjoy!

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1 Comments:

Does any GIS staff has experience with many types of visual analysis, can you tell me about some who can help us

By Anonymous GIS, at 5/31/2007 04:26:00 AM  

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Friday, November 24, 2006

Reitoru Atoll FP

Reitoru Atoll FP

Reitoru Atoll (17˚50'S., 143˚06'W.), a low atoll, has no en-trance into the lagoon.

(SD Pub-126)

More information about Reitoru Atoll can be found at an interesting link that gives some facts about the very small population that makes a living from pearling.

This is the finished map with vectors taken from the Google Earth 1-meter resolution image. The map took about four hours to complete. It is a very solid effort.

Enjoy!

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Tuesday, November 21, 2006

How To Georectify Images Using Global Mapper

Landsat Image

Landsat Image

Last night, I was searching for an island to work on. One not too large, but one I could finish in a single evening. I came across the above atoll. It is called Reitoru Atoll and is located in the Tuamotus. It looked like a great candidate.

As I do on all my projects, I searched various sources for more detailed imagery and Google Earth (GE) had it...cloud-free, 1-meter resolution of the atoll. I typically don't work in Google Earth to digitize, preferring Global Mapper (GM) instead. Before I can work off of this imagery, it must be loaded into GM and be georectified to ensure the vectors are created where they belong.

Image Rectification with 4 GCPs

Image Rectification with 4 GCPs

Georectification uses an original image to apply the same lat/lon grid to a new image. Given enough Ground Control Points (GCP) applied to shared geographic features, the new image (GE image) can be easily laid on top of the original image (Landsat image). Upon loading a raster image in GM, you are asked if you would like to rectify the image or load it to view. Since I wanted to digitize from the new image, it was necessary to rectify it.

The actual process consists of five-steps for each GCP. Step-1: Select an outstanding feature identifiable on both images. Step-2: Zoom-in to clearly encompass the feature on both images. Step-3: Selet the feature location on the original image. This becomes the initial entry that will become the 1st GCPs lat/lon. Step-4: Select the same feature location on the new image. This is defined by its pixel location. It completes the entry for the 1st GCP. Step-5: Select "Add To GCP List", then move to the next GCP to georectify.

I use something called the Polynomial with 4+GCPs to georectify images. If an image needs to be tugged or pulled this method allows it. Ultimately, the images lay directly on top of each other - the new image on top of the original image. GM allows me to manipulate the new image to guarantee the best format from which to create my Enhanced Vector Shorelines (EVS).

Georectification with 4 GCPs

Georectified Google Earth Image

Once the new image is georectified, I am able to create a very high quality product that I can then share with my readers. And that is how you georectify using GM. Isn't it easy?

Enjoy! And have a Happy Thanksgiving!

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3 Comments:

Seems to me like you could have saved a step: Loading it into the Map Rectifier from MetaCarta seems like it would have been a great way to rectify... unless I'm confused. It seems to me that you do have two images for which you already know the geography, so I'm not sure what was achieved by rectifying here, so maybe I'm wrong.

By Anonymous Christopher Schmidt, at 11/24/2006 05:54:00 AM  

I could have tagged the GE image and included lat/lons. However, in this case I took a screen image without coordinates. What I showed in this post was the end result of my georectifying process. Although the new image could have been geotagged making the georectifying process faster, GM's process allowed me to successfully drape the GE image onto the Landsat image.

By Blogger Mr Minton, at 11/24/2006 08:38:00 AM  

Very interesting!
I am confused (amused) at how little I understand about mapping. For instance, hills/valleys are compressed and actually greater(in length) than they appear from ortho view aerial photo.
Q: Does this mean that maps inherently compress hills & valleys?
Q: Does this (also) mean that parcels of land on hills/slopes actually more net area/acres (ie. Farmable) land than the land survey (flat projection) would state?

By Blogger stevegyro, at 12/17/2010 05:27:00 PM  

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Monday, November 20, 2006

Tehuata Atoll FP

Tehuata Atoll - Landsat Image S-07-15_2000 (1-15,625)

Tehuata Atoll - Landsat Image S-07-15_2000 (1:15,625)

Tehuata Atoll - Marplot Map (1-15,625)

Tehuata Atoll - Marplot Map (1:15,625)

POL - Tehuata Atoll

Tehuata Atoll aka Rekareka Atoll is small in comparison to it's neighbors. According to the UN Island Directory entry for Rekareka Atoll the island is uninhabited. Most probably the island is visited to harvest copra. The digitizing was fast and uncomplicated. GE has a 1-meter resolution image available for this island. I might use it later. I did a quick comparison and find that what I mapped is good.

Tehuata Atoll - Google Earth Image (1-15,125)

Tehuata Atoll - Google Earth Image (1-15,125)

Tehuata Atoll - Marplot Map (1-15,125)

Tehuata Atoll - Marplot Map (1-15,125)

Okay, I am a perfectionist. I couldn't leave the map alone. Using the Google Earth 1-meter resolution imagery as base, I checked out my original vectors. A few minor adjustments. The primary change was a layer classification. I renamed EVS Land Gravel Sand, which I used once on Caldey Island UK, to EVS Land Distressed Sand. I believe that the grey sandy portion of the island is salt-water saturated. I like distressed sand instead of water saturated sand. Lots of things can distress sand besides water. And since it is my map, that is what I will continue to call it.

Enjoy!

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1 Comments:

This is really fantastic! The detail and accuracy of your maps is really amazing. :D

By Blogger Callista, at 7/22/2010 01:47:00 PM  

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Thoughts - GIS Blogger bloggers and Planet GS

If it wasn't for James Fee and his excellent work on Planet GS many GIS blogs would be read by the blog author and his or her close and loyal friends and family. Planet GS has allowed me to share my island projects with thousands of people throughout the world. I owe much of my blog's success to Planet GS.

My work is well received, being viewed by 50 to 100 visitors daily. My posts of island projects are typically found in the top five site references for a Google search. My point is - I am what I am (blog-wise) due to the quality of my work, the breath of my posts and the exposure offered by Planet GS.

So, it was with a great deal of displeasure I read the "Blogger Bashing" thread on James Fee's website dated November 02. To a person, everyone had fun bashing Blogger and the spamming-like problems that it supposedly creates in Planet GS.

As a Blogger blogger, I don't think the problem is with Blogger. The problem is with the blogger (little "b"). That is the individual blogging. Not all of us are HTML-pros. Not everyone works on the coding side of GIS. Some of us just have GIS-related ideas to share and Blogger is a great vehicle to carry our ideas forth. We sometimes screw up and post when we shouldn't post or post silly content. That is a problem of the blogger, not Blogger.

What am I trying to say? I resent that my site, EVS Islands, shows up on a list of Blogger derived sites (see the above link) as if it isn't worthy to be listed alongside non-Blogger sites. That is a bunch of elitist crap! I work long hours to ensure the quality of my posts meet my high exacting standards. I labor long and hard to maintain a consistently high standard of content. I never, knowingly, produce trite commentary, but strive to share topics relevant to my special interest, Enhanced Vector Shorelines of islands.

My product, high quality island maps, is for everyone, not merely the GIS expert. I am sure my readers include bored office workers, students and elderly dreamers. Great! And Blogger is how I am able to share my work.

James Fee - your work with Planet GS has allowed my product and that of others to be widely viewed throughout the world. If someone is messing up, determine the problem and let them know with a personal email. If they ignore your fair warning, since Planet GS is your site, delete their feed.

All of us in the GIS community truely appreciate Planet GS and all that you do.

Most especially this GIS Blogger blogger.

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2 Comments:

You'll notice that your feed is still in Planet Geospatial.

I only remove blog feeds (any type) after they spam Planet Geospatial twice. First you get a warning, then it goes. While the problem is 90% Blogger (I can't replicate it so you might be right it could be the blogger on Blogger), if the blog is on Wordpress.com and does it, then it too can be removed. Since I've removed about 5 problem feeds in the last 2 weeks, I think PGS has become much easier to read.

I do take a little exception with your blogger bashing comment. I mearly listed all the Blogger hosted feeds to show people it wasn't as simple as just removing any blog with "blogspot.com" on the end. My comment was to show that there were good blogs in the list and I didn't want anyone to forget that.

By Anonymous James Fee, at 11/20/2006 06:14:00 AM  

I thank you for your prompt reply and thank you for your clarification. I know that you work dilligently to maintain PGS as a high-quality resource for all users. Perhaps it was me reading the thread at 3:00 AM (I couldn't sleep), where your comments remained neutral, many of the responders seemed determined to isolate Blogger as the problem. And that is what I reacted to.

Again, PGS is great and as a GIS'er and Blogger blogger, Thanks!

By Blogger Mr Minton, at 11/20/2006 06:23:00 AM  

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