Eye-SAH-Ryth-mik Mappin'

This week was isarithmic mapping...or how those contour and weather maps are made. Isarithmic mapping is different from choropeth mapping in that the data is not bound by enumeration units. Isarithmic mapping is good for data that doesn't correspond to to the artificiality of borders, data like weather patterns, other natural phenomena or even human activity that transcends enumeration units (population distribution as opposed to density). Isarithmic mapping works best with continuous smooth data.

First, in order to understand how isarithmic maps work, one needs to know interpolation of the data points. Enumeration units are not used, points are used instead. These points can be "true" (a weather station) or "conceptual" (data from over a larger area placed into one point). This, for me, wasn't that easy to grasp. Our book had tons of little formulas for the variety of interpolation it presented us with. I suppose though, knowing the basics is what's important because as a GIS user, I can better display and explain the information if I know the process that went into creating it. Like a car salesman who knows the basic of automotive assembly.

The objective for the lab was to use isarithmic mapping and display the data through 2 different symbologies. The first was continuous tone which shows colors or shades proportional to the data being displayed. In our case, the 30 years average of precipitation in Washington state.  The colors in a continuous tone map sort of flow into each other and I feel, is easy for any map reader to understand.

The second was hypsometric mapping. It's similar to continuous tone however it's used more to show how the data is impacted by elevation. I feel hypsoemetric mapping is somewhere in between choropeth mapping and the continuous tone symbology in that hypsoemtric almost creates clear breaks in the data. Those breaks are the change in elevation. It's useful when elevation's impact on the data is important. Below is the final map product, a hypsometric map with contours. The contour lines help to illustrate how hypsometric creates breaks based on elevation. Those breaks almost create the appearance of an enumeration units (knowing that there are no enumeration units, but instead points).

I feel the map, with it's symbology, shows use where precipitation is greatest by elevation where as the continuous map shows us a more general trend in precipitation.

This map presents us the 30 year average of rainfall over the state of Washington. It uses hypsometic symbology  and contour lines (see above). The data was created using PRISM. PRISM uses point data underlined with elevation and is related to "climate fingerprint" or the historical weather pattern of an area based on it's physiology (mountains, etc.).  

Thinkin' Design: Module 4 Lab GIS 3015

This week's objectives are to use Gestalt's principles in creating a map. We had to use visual hierarchy to help display information. Using VH well creates a balanced map that shows the 

end user the most important information while maintaining the needed geographical references.  

In my map, the first thing to do was to decide the colors I was going to use. I had to make sure the colors provided contrast without impeding balance. Sort of like using the right amount of seasoning

in a meal. Rosemary adds a nice flavor, but if overdone, it can ruin the meal. Again, I went with green. I don't know why but I find myself using this color a lot.  I feel I was able to create a good contrast using green. As you'll notice,  the DC area to the west and south of Ward 7 is lighter than Ward 7. If you look at it, your eyes start pushing towards Ward 7. Those DC areas provide reference without overwhelming the map. Now that your eyes are in Ward 7 (you may also notice that the white  background outside of the DC areas pushes your eyes toward Ward 7) you'll immediately notice the red icons. They jump out and you can quickly discriminate between  the different levels based on their shape. The river, I made a dark blue. Initially, the river was a lighter blue but the bridges blurred into the river and that blur was distracting. The colors were ultimately created in AI. 

Creating the map, I began in ArcGIS. I created the basics there: the symbology, the insert, the roads, etc. With the roads, I added state hwy 295. It's the only highway that cuts through Ward 7 (as far as I could tell). Adding the other highways and interstates didn't make much sense to me because they were outside ward 7 and my scale is around 1:35,000. When I turned those layers on, they would be in the left hand corner or towards the lower left hand side. The insert was easy to make. All you need to do is create a new data frame and place the layers inside that. You can even duplicate the layers (right click, copy). The extent was created by going to the properties and extent tab. I went with a red box. With the legend, I inserted it but that shows all the active layers. So I right clicked, properties and then moved all the items out except the schools. I listed the schools by level by going to the layer, right clicking and going to the symbology tab. In there I created categories based on levels (which were already in the data). I assume ES, MS and SHS were all abbreviations for the various school levels. I edited the labels, removed the heading. I then searched for a good icon. At first, I went with the little red school house icon that was used in the pdf. I decided that I didn't like because, even if you changed the sizes, it was still hard to discriminate. Instead, I went with the icons you see below. They're similar but different. I feel those icons make it easier to know what kind of school you're looking at without going back to the legend to keep checking. After all of that, I exported the mxd to AI. I changed the colors to my "better" greens and added the title. I kept the title inside the map area and created a color pattern (white with black outline) and a drop shadow that would help make it stand out and easy to read. I added a drop shadow t the ward 7 area that I think helps, but it is inconsistent. I added the border by creating a  hollow fill rectangle with a thick gray border. I'm really starting to enjoy using AI (my swearing was considerably less when manipulating layers and figuring out other things). 

The whole time, I was thinking in minimalist terms for everything including the insert map. My take away from the text was keep it simple ( albeit based on the needed information and audience)  

Side notes:

In ArcGIS I used the selection tool to select elements within Ward 7 and then exported that data as a new shape file. I then removed the previous shape file that I didn't need anymore. I did this with the schools and I even did it with the river and parks. I really enjoy using that selection feature. It really helps. 

I'm not too worried that I cut off bits of ward 7 (this is also shown with the extent box in the insert). It helped me make the area  a little bigger without taking any relevant information out. Our design starts with looking at the geography of an area.  It dictates the layout and placement of everything. (well duh right).

I'd like to take a litte time here to discuss alternate GIS programs. I was having connection issues (I need to use a VPN) and so I exported the data to Q-GIS which is already on my PC and played around with it. I found Q Gis to be faster than Arc and the maps look nice as you create them. Ultimately, I abandoned it (mostly because there's a lot to learn in Q-GIS) but this open source suite (along with others) may be worth the time to learn. It's free and seems quite powerful, at least for map making. I'm unsure of it's GIS analysis capabilities.