ArcMap 10.1 Tip - Importance of Projection

incaseyoucare:

So I had to create a 2kmX2km grid inside the polygon boundary of Ecoregion 135 for a new sampling project. Easy - I’ve made grids in polygons before. No sweat. So I go to make the grid, which I want to run straight N-S, and it ends up like this: 

image

Hm. It’s crooked >_< The fishnet tool was created by a co-worker of mine, and I don’t really understand Python THAT well, so I was just gonna wait until the next day to ask her or my boss. But then, after a night of thinking about it, I realized I should check the projection of the actual boundary shapefile. Every other polygon’s projection, that grids had been straight for, was NAD83 UTM18N in Transverse Mercator. So I checked the tilted grid and BAM, it was Nad83 Lambert Conformal Conic. Heart beating slightly faster with excitement, I opened up the tool to switch projections. 

image

I fixed the projection of the boundary shapefile, then re-ran the fishnet tool, and huzzah, the result:

image

So if ever you encounter a wonky looking shapefile, be it a line or a polygon, or something doesn’t line up right, make sure the file is in the correct projection!! 

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trilobitespentrasbildojn:

Welp, classes start a week from today. I just got back from my new-faculty orientation… though admittedly my ‘faculty’-ness has yet to thoroughly sink in. Still working on lesson plans…

I am halfway considering pulling out my big black cloak, asking my former-colleagues in the university library to help me locate a suitably large, arcane-looking, and preferably dusty volume of something or other, and showing up to the first class claiming at first that GIS stands for ‘Geomancy, Incantations, and Summoning’, if only to be less daunted by the whole endeavour…

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