GIS5007 Isarithmic Mapping

This week we tackled Isarithmic Maps.  These maps depict smooth, continuous phenomena across an area, like precipitation for example. This is exactly what we we tasked with creating this week. Before creating our maps we first has to learn about the two different types of data; true point data where the values are measures at a point location, and conceptual data where values are collected over an area but are presumed to be point locations.

Next, we covered four different interpolation methods which are used to predict unknown values for a data set. The first was Inverse Distance Weight (IDW), second was Kriging, third was Splining and lastly was Triangulation.  For our lab we were provided with precipitation data which was downloaded from the USDA Geospatial Gateway. This data was derived and interpolated through the utilization of PRISM (Parameter-elevation Relationships on Independent Slopes Model).

With this data we first created a map using continuous tones. We changed the color scheme for our Annual Precipitation layer to Precipitation. Next, we added a hillshade effect layer. In this layer we edited the continuous color scheme giving it 6 colors with specific settings. This is the resulting map layout.

Our next step was to create a map using Hypsometric Tints. We used the same Annual Precipitation and Hillshade Effect layers in this map. We used the Int (Spatial Analyst Tool) and ran it on the Annual Precipitation raster to create a new layer. Once this was completed we removed the original Annual Precipitation and replaced it with this new one. The data was then manually classified into 10 classes and symbolized with a Precipitation color scheme. From  here we created contours using the Contour List Spatial Analyst tool. This is the resulting image.

Now having all the pieces we were tasked with putting together a final map layout using the cartographic design principles we learned in pervious labs.