Lab 5 questions

1.0) What does 7.5' represent in the name 7.5' DEM?

1.1) What is the horizontal resolution of 90as30.asc? What is the vertical resolution of this particular DEM? The original resolution of a DMA DEM is 3 arc seconds (3/60 of an arc minute or 3/(60*60) of a degree). At 33 degrees North Latitude, one degree of latitude is 100.9km, and one degree of longitude is 93.4km. What is the original horizontal resolution, in meters, of this 3 arc second DEM. Show all work.

2.0.a) What is the resolution of your DEM? Describe all of the metadata characteristics used by Arcview that define the spatial location of your DEM (information in the theme's properties).

2.0.b) You have the ability to modify the resolution when performing analytical functions in Arcview (and any robust GIS). If you increase cell resolution for the analysis (for example, from 100 meters square to 200 meters square), the amount of time to compute the results, as well as the resulting output map's size, will decrease. Assume the following:

How much faster will the analysis be done? Note that there is a clock at the bottom of your Windows screen. Show your work (equations). For example, you may wish to calculate the number of pixels processed per second in each case.

2.2.a) Generate a layout with a hill shaded relief of your DEM overlain with contour lines. Make sure your name(s) is in the legend of the map. Send it to your TA in the manner they wish to receive it.

2.2.b) Generate a hill shaded relief of the 90as30 DMA DEM with the same hillside parameters as the  hillside theme of your DEM. Compare the two DEMs by looking at the two hill shade maps (by themselves) and describe the differences you see. Why do these differences exist?

3.2.2.a) Which slope map, the original or the doubled resolution, has larger slope values? Why is this so? Compare the differing slopes to the Modifiable Area Map problem. What are the similarities between the two situations?

3.3.1.a) Explain precisely what the equation: likelihood purchasing supplies = 0.8 - (km from city) * 0.005 means. How was it derived from the assumptions?

3.3.1.b) After building the "likelihood of shopping at a computer store" map, you realize there is a problem with this map. What is wrong with this map? There is an problem with the assumption of linearity. Although Illinois is flat, what spatial features makes the linearity assumption not ideal (the information is available in the US Arcview data set for the US)?

3.3.2.a) Compare and contrast Arcview's proximity analysis in raster mode with buffer analysis in vector mode. Describe an advantage each has that the other doesn't have.

Make output files or printouts (whatever the TA says) of the maps from 3.3.1 and 3.3.2. Don't forget to include city locations as well as state boundaries. The easy way to get a state (or any polygon) boundary is to click on the "outline" icon -- upper left -- in the fill palette of the legend editor.