Posts Tagged ‘geography’

Cartography and Ringmaps

Posted: November 9, 2013 in GIS
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The latest issue of ArcUser magazine (Fall 2013) has a great article and step-by-step instructions on how to create ringmaps (see “Looking at Temporal Changes”) along with a toolbox that can be added in to ArcMap. The article is well written and the toolbox that goes along with it is very clean, simple, and quick. The thing to watch for, especially with these kinds of maps, is the cartography. Making the map is great, but getting the right symbology, legends, etc. on the map is also critical, and ringmaps have some unique features.

The first and most obvious are the rings themselves. Identifying what each ring stands for is very helpful. In the example I created based off of the article, the inner ring stands for 2006 data and the outer ring for 2010, but how best to show it? I chose to insert the years into the rightmost rings themselves as text objects. This denotes them without detracting from the map or taking up space with another legend item. Another issue that has to be watched is the polylines that connect the rings to the map. I converted these to graphics and then adjusted them. I also annotated the labels for the counties and adjusted both these and the polylines to be as near the center of the county as practicle, but also watch and make sure that no two polylines crossed near where on ended, making sure it was clear where each line ended. I added the standard north arrow (I went fancy here just for show, the simpler the better with north arrows), the small text and information on where the data came from, and a scale. The scale in this case is not really necessary, but fills in some extra whitespace and helps balance the area. The last item is the legend. Ringmaps are mostly used to show trends, as this one does, so having the actual values in the legend is not as important as identifying the trend. In that case, I went with a low to high method which simplified the legend, helps the reader understand the trend, and makes for a cleaner design. If this was being used in a research paper or report, then I would assume the actual numbers would be found in a table or discussed in the body of the text.

Ringmaps are great and I have plans to use them in a upcoming paper I am working on and so this article and toolbox was very helpful and timely. The things I have shown here are not the only or best way, but work well for me. Try it yourself and let me know what results you come up with and where you see I could improve on this one.

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What do you see in the image below? A series of black blobs, or the words MAIL BOX?

mailbox

 

 

I recently started reading the book “Gödel, Escher, Back: an Eternal Golden Braid” by Douglas Hofstadter, and Chapter III really got me thinking. The chapter is on Figure and Ground, which mainly relates to art where the figure is the subject of the artwork and the ground is the background. Hofstadter’s book, though, is not so much about art as it is about logic and the way we think and perceive the world.

I started thinking about figure and ground from a geospatial point of view. As an example, let’s say we are analyzing an area of interest trying to determine a specific type of habitat or feature. Depending on the type of analysis, the features we are looking for may be small, complex, or not neatly defined. But what if we looked at it from the point of view of what is not our target feature? Then, like in the image above, the ground becomes the figure and the figure becomes the ground. Similar to the way astronomers used to look at the glass plate exposures from their telescopes. They would look at the negative image where the stars were black on a clear or white background, thereby making them easier to see because of the contrast. Using this same idea applied to geospatial analysis, in some cases, might useful in highlighting the areas we are interested in by looking at what it is not.

References

Hofstadter, D. R. (2000). Gödel, Escher, Bach: An eternal golden braid : 20th-aniversary edition with a new preface by the author. N.Y: Penguin Books.

 

Finally had a chance to make some changes to the site, so here is what’s new.

  • I have started a seperate page for the Putnam County @ Your Feet maps and moved the bedrock layer over to that page. I hope to have a surficial layer map up soon.
  • I am also creating a page for some heat maps and other items I am working on using the 911 call data from Putnam County, Indiana.
  • For my Advanced Remote Sensing class this semester, I am working on identifying Bobcat (Felis rufus) habitat in Southern Indiana. I will post the results of that here at the end of the semester and ask for feedback.

Besides maps, I am also taking a course on Applied Spatial Statistics (go Bayes’ Theorem!) and also data visualization class. Hopefully I can start adding some analysis to the maps and projects soon. As always you can follow my blog (I don’t post much so I won’t be cluttering up your life), also on Twitter (@JeffreyAshby) and on Facebook (jeffrey.ashby1).

The First Post

Posted: October 22, 2012 in Uncategorized
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So to start of this blog dedicated to GIS and Geography, I thought I would toss out a few quotes I stumbled across while sauntering around the Internet.

“Everything has to do with geography.” – Judy Martz

“Geography is important, because it opens our eyes; a landscape is no longer a static feature, but a complex battleground of physical and human interactions. Local is no longer local, but a collision point for the interaction of many ‘locals’ drawn from a global stage. With technology increasingly drawing the world closer together, it is important that the role of Geography in helping the public in understanding this complex and unpredictable world is championed!” – Tony Cassidy

“Anybody who believes that the way to a man’s heart is through his stomach flunked geography.” – Robert Byrne

“If geography is prose, maps are iconography.” – Lennart Meri

Ok, that’s enough for now. I plan on posting about projects I work on, modified versions of assignments for classes, stuff I do for fun, and any other geographic and GIS items that come across my desktop. Some of it will be informational, so whimsical, and some tutorial. If you want to know more, check out the About Got GIS? And Jeffrey Ashby page for more.

I am currently looking for a job in the GIS field, so would appreciate your help in finding one. Preferably in the Indianapolis, Indiana area, or Central Indiana, or the United Kingdom, or Sweden, any of those areas are good.

I am a member of the Association of American Geographers and Golden Key International Honour Society. While most of what I do and show will be using programs like ArcGIS and ERDAS Imagine or Exelis ENVI, I may also delve into some of the open source programs like QGIS and Multispec.

Geography is fascinating to me, the where of it all, but with the tools available today we can use a combination of GIS and Remote Sensing to understand our world far better than at any other time. From knowing how well the crops are doing in the fields (and what is being grown there) with space based imaging systems, to knowing who will be affected if a dam should break. It is an exciting time and I can only see it getting better.

Did I say check out the About page? Get over there and look at some of the cool things I have done, then drop me a note at jlashby@iupui.edu.