Dot density maps can be powerful tools in displaying certain types of data.  This week we were asked to map the population density of counties in South Florida.  Using a surface water layer and a modified land cover dataset for urban land, we were able to place the dots in locations where the populations actually existed and not randomly spread throughout counties.  This made the appearance of the map much more realistic and meaningful. 

The assignment was well-conceived and working through it would enable me to accomplish the learning objectives.  Those objectives were assessing the overall design issues for dot density mapping, utilizing the arctool Excel to Table, creating a dot map in ArcGIS, experimenting with dot weights/sizes, and handling dot placement.

The assignment was challenging due to problems with ArcGIS crashing while experimenting with dot placement.

Despite my problems with ArcGIS, viewers should be able to see the effectiveness of dot density mapping to demonstrate the intensity of particular kinds of point data.

Flow line mapping was this week’s focus.  Using Adobe Illustrator, we were asked to create a flow line map reflecting immigration to the United States in 2007.  Another component of the map was a choropleth representation of the US using a five-class symbolization of the percentage of immigrants to each state.  The objectives of this lab was assessing design issues, using proper design techniques, and applying effective style and/or visual effects to create a compelling flow line map.

I utilized a drop shadow for both legends as well as for the title and subtitle.  I felt this made the elements more prominent.  I rotated the titles for some of the continents to better flow with how they situated on the map.  The flow lines were placed with graduated shades of black/gray corresponding to the level of immigration from each continent.  On the regional immigration legend I used a dashed line to connect the totals to the name of the continent for easier viewing.

This was a valuable learning experience and another chance to refine my skills in Adobe Illustrator.  Hopefully, the audience is able to quickly grasp the answers to these questions: 

(1)    Where did they come from?

(2)    Which continents provided the most/least immigrants?

(3)    Where did they end up?

If they can, then I've done my job.

Isarithmic mapping is one of the most popular methods of displaying data that is smooth and continuous.  The contour map is the most common style of isarithmic map and is widely used to present data on topography, elevation, and rainfall.  This week’s lab required that I make two isarithmic maps depicting average annual rainfall in the state of Washington.  One map would be symbolized with a continuous tone while the other would employ a hypsometric tint design.  Both maps would also use a hillshade effect to enhance the data contours.

The data for this lab was gathered from the U.S. Dept. of Agriculture through their Geospatial Gateway website but was originally created by researchers at Oregon State University by using an interpolation method called PRISM (Parameter-elevation Relationships on Independent Slopes Model).

Map 1 was titled “Continuous Tone” and was symbolized with the Precipitation color ramp provided by ArcMap.  I added a vertical legend and stretched it so the numbers and colors were easier to read.  I also added some key cities to the map to serve as a reference for viewers unfamiliar with Washington geography. 

Map 2 was titled “Hypsometric Tints” and symbolized in the same manner as Map 1.  For Map 2 I utilized a horizontal legend and manually adjusted the 10 classification values that were called for.  To make the classes easier to display in the legend we used a tool from the Spatial Analyst extension that rounded fractional numbers to whole numbers.  Another difference between the two maps was that for the hypsometric map I added contours at specified intervals related to the amount of average annual rainfall.  To add a bit of craftsmanship and refine the map I decided to make the precipitation layer 20% transparent and placed the contour layer below.  This arrangement offered the benefit of the contours layer without giving the map a cluttered appearance.  I felt this really improved the readability of the map when combined with the hillshade effect.  

I hope the audience will come to appreciate how effective and powerful isarithmic maps can be in understanding our world.