Day 35: It’s the end of GIS (sadly), but maybe I’ll get to spend less time starring at my laptop and hissing

A few days ago when I leaving class a little late because all my rasters were turning out strange and squiggly, I noticed I was blinking a lot upon leaving the building because it was…bright? The sun was up with no clouds! I had to just stand on the sidewalk and bask for about five minutes.

Hello Sun!

I can’t really say I disliked it being dark all the time (I loved the stars too truly to be fearful of the night, and all that), and it was interesting having a day/night cycle as disconnected from the world as I usually feel to it, but is nice to see the sun again. Even if it isn’t on the regular because of clouds rather than astronomy, but oh well.

Today’s snowier view, of grey skies and grey mountains and grey water.
It’s still pretty, just grey.

We finished up the GIS class today, so everyone did a little presentation about the maps we’ve all been making for the last week. I half remembered that there was an equation involving soil moisture and soil depth and slope angle and some other things that you could use to calculate landslide risk. Basically, you sum up the forces holding the hillside together and sum up the forces pulling it apart, and if the pull-apart forces are bigger than the hold-together forces, your slope is unstable and at risk for landslides, whereas if the fraction of hold-together over pull-apart is much bigger than 1 your slope tends to stay put. So I did a lot of scrounging through USGS to find the requisite soil data and hot damn but those people don’t make their website easy to navigate. I know it’s free to use to the public, and I’m very grateful, but the search function for data sets is crap and it’s very easy to get stuck in little link whirlpools where the pages all link each other and never actually take you to a data set.

Anyway, I got my data set, I did my unit conversions (because Americans continue to insist on measuring things in slugs per square inch. no, I’m not kidding), and extracted all my rasters, which would insist on being slightly scronked due to projection trouble I never actually manged to solve but hacked around instead, it was time to do the calculations. Which meant repeatably putting a complicated algebraic expression into a raster calculator. Luckily I put the whole function in a text file First, which saved me oh god so much effort, but even so I had to do a lot of end-parenthesis hunting whenever I realized I’d mistyped while substituting a value, or needed another set of parenthesis to clarify a division. Truly, the smartest thing I did all project was put this: ((“cohesion@1″)/((0.75″dry_weight@1″+ 0.25″wet_weight@1”)+”depth_m@1″+sin(“slope_deg@1″)))+(((0.25″wet_weight@1″)/(0.75″dry_weight@1″+ 0.25″wet_weight@1”))(tan(“soil_int_angle@1”)/tan(“slope_deg@1″)) ) into a separate file so I could copy and paste it with different moisture values rather than typing it out every time, because naturally the built in calculator to the mapping software doesn’t have ”last function please”. ugh. I did not miss parenthesis hunting from programming, I really didn’t.

a Map!

But I made a map! and I’m actually pretty please with it! The professor suggested that I add the equation and the mini-Massachusettses both for visual interest and to try and explain how I got the results I got, and I realized far too late in the game that with each raster layer laid out like that, it looks a little like a pride flag. Ah well. It is both visually interesting and deeply appropriate for Massachusetts. It also occurred to me only after looking at everyone else’s map that I had built a project that required me to do absolutely no fussing about with labels, which is the Worst part of mapping stuff.

I made a cake last week (spare raspberry jam into the practically perfect Fanny Farmer gold cake with chocolate frosting) into between fugue states of trying to get the mapping program to do what I wanted it to, and told the housemates they could have as much as they wanted. And it’s still here? At home, I’d be very surprised if a cake lasted three full days with three people in the house, but here it is, six days later. I keep forgetting most people don’t eat as much dessert as we do, in the same way it’s not normal to budget a pound of potatoes per person or a minimum of four biscuits. I don’t understand these people; they looked at me like I was a weirdo for grabbing a slice for breakfast. Luckily, it turns out that one of magic things about this cake is that it always tastes better on the second day, and while it doesn’t continue to improve over five more days, it still isn’t stale and is instead delightfully edible.

Sadly, this is the end of the GIS class, but the next one is Fisheries Management, which seems like it should be a fascinating class, if one of those professions where everyone is mad at you all of the time because everybody wants something else. The guy who’s teaching it is a fish biologist though, so I’m guessing he’s going to have a pro-fish bias.

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