Sunday, October 14, 2007

Sunday, Oct 14th Chap 10, 11 exercises

The test wasn't so bad but there were a couple that I just wasn't sure about. For example the last question: what are the two table types. Ya got me.

I mostly studied from the book so I couldn't remember what Isopleth maps are, even though I remember you mentioning that word one day.

This weeks exercises were quite interesting...clipping data, etc.

Tuesday, October 9, 2007

Tuesday, Oct 9th, 2007 Large vs. Small scale

Aldous Huxley said, "the mind is a reducing valve". In studying for the exam this Friday, I am struck by how maps are abstractions and reductions of reality. They are a metaphor for everything in life because everybody's experience at any moment of the day is just an abstraction of the reality. What we experience is just a tiny fraction of the complexity of all that is occurring at any moment. In map making we are forced to reduce. You could never make a map of all the detail that exists, and people don't want that. They want the complex boiled down to a subset of important features.

The confusion over 'large' scale vs. 'small' scale is understandable, but I think I have it straight in my mind now, but it still requires a conscious effort to overcome the instinctive impulse to assume that 'large scale' means a map that covers a large area (e.g. the entire U.S.) A large scale map covers a smaller area and has more detail than a small scale map. The words, large and small, refer to the ratio, or fraction. As in , 1/10th is larger than 1/1000th.

This confusion reminds me of when I worked in a payroll dept. We were paid twice a month and everyone called this the "bi-weekly" payroll. It drove me nuts because it should have been called "bi-monthly". Hard as I tried to change this usage, most people just resented me for it.

Friday, October 5, 2007

Friday, Oct 5th, 2007 -- Joining Tables

Today we pulled new data sources into our Map. This was very interesting because I can imagine that there are many times when valuable data is outside the original map document. It was also great to see how to query and restrict the data.

I want to get the Buncombe county data and do some queries, like how many parcels > 100 acres in east Asheville, where I live.... or, how many parcels are valued at greater than a million dollars, etc. Fun stuff.

As long as you have some common data element, like PID, PIN, you can tie the data together. Very cool.

A lot to study for next week's test.