Thursday, March 5, 2015

GIS3015: Isarithmic Mapping

The last two weeks have been quite challenging and more fun than anyone should be allowed to have. I am so happy to finish week 8! This week, I learned all about Isarithmic Mapping.  The learning objectives were:

- Understand the PRISM Interpolation Method
- Work with continuous raster data
- Implement continuous tone symbology
- Utilize the legend wizard and properties to make map appropriate legends
- Utilize the Spatial Analyst Extension
- Implement hypsometric symbology
- Employ hillshade relief
- Use the Int Tool to convert floating raster values to integers
- Manually classify data
- Create contours using the Contour List Tool
- Use the Spatial Analyst Toolbar to create graphic contours
- Compile maps using craftsmanship to create unique and polished Isarithmic maps.
- Summarize and present lab objectives and outcomes

After the Choropleth map (last week's assignment), the isarithmic map is probably the most widely used thematic mapping method dating back to the 18th century. Isarithmic maps depict smooth, continuous phenomena, such as rainfall, barometric pressure, and topography or elevation. The most common form is the contour map. Contours are lines that connect locations of equal value. They can also be referred to as isolines (iso means equal or the same in Latin). Additional terminology is used in reference to contour lines depending on what is being measured: Isopleths depicting general meteorological features, isobars depicting barometric pressure, and isotherms representing points of equal temperature. All of these are forms of isarithmic maps.

The task was to make two maps (depicted below) with data for the state of Washington. The data is prepared using PRISM. That stands for: Parameter-elevation Relationships on Independent Slopes Model. I elected to use contours on my hypsomatric map. Hypsometric tinting differentiates contour values with stepped color shading. The Continual Tones map makes a pleasant presentation but my favorite is the Hypsometric Tints with Contours map.  Hope you enjoy both these maps!

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