Question 2

How does a projection influence GIS representations?

Every GIS professional should be able to use the following concepts proficiently:

• Projection
• Central Meridian
• Standard Parallel
• Tissot's Indicatrix
• Conformal, Equal Area

In specific, practicing in North America in the current era, these are implemented as:

• State Plane Coordinates
• Universal Transverse Mercator
• (in other areas there will be National Grids, etc.)

1. "Professor, the map is tilted"... A quadrangle of USGS data (in either UTM or State Plane will appear "tilted", although the sides are meant to be meridians (hence directly north-south). Explain this phenomenon with reference to projections. What would you as a user do if your map readers are bothered by this? Where should you expect this to be a larger (or smaller) problem?
2. Scale error is unavoidable, it is just a matter of where it is located. GIS makes great use of perimeter and area measurements in the attribute tables of all areal features. How large is the effect of using UTM and State Plane within their intended areas? How much worse is it to use Washington State Plane South zone extended into all of northern Washington (as DNR does?) What would you reommend for a statewide database?
3. Standard coordinate systems are meant to enhance communication, but the number of standards make this somewhat complex. Should a GIS manager bother to use a standard? If so, which one, or if not, what custom projection might be more useful (specify your application area).
4. Consider what tradeoffs to make in producing a set of thematic maps for an Altas of the World (for some purpose...). What projections might serve your purpose? Who would be offended by your choices?

Your answers shouldn't be much longer than one page... See links from Lectures 4 and 5.