Zoning in on Landcover
We look at summarising vector polygon data within larger polygon zones using two different workflows. Polygons give us a handy way of creating zones, within which we might be interested in knowing what’s going on. Think of country boundaries, regions, school zones or even your own property boundary. Within those zones we often need to […]
Overflowing with River Data
We review several digital river networks and how they can be used. Spatial data for rivers are one of those fundamental data layers needed for many different kinds of analysis, along with elevation and landcover. Over the years there have been a few different datasets available so we’ll do a quick survey and see how […]
That Red Light
We use GIS for a bit of detective work with lines of sight, compass bearings, viewsheds and webmaps. (I’ll apologise at the outset for the quality of some of the images in this post. My camera doesn’t work that well in low-light situations.) As we stood out on the porch of friend and colleague Erin’s […]
A View from the Tops
A weekend walk gets us thinking about the tramping season. A walk up The Monument Track to Te Ahu Pātiki (Mt Herbert) over the weekend got me thinking about the up and coming tramping season. The family has the Heaphy Track planned for September so this was a bit of a warm up. One of […]
Degrees of Distance
When measuring distance it pays to be aware of which coordinate system your data are using. Hot off a discussion of coordinate systems and map projections in the GIS courses, I was reminded of something that threw me for a loop with some of the global scale analysis we’ve been doing lately. This one was […]
That Cat(fish) Scratched Back
We look at extending our marine ecoregion polygons to get more observations categorised – not as straightforward as it might sound. In a previous post we looked at extracting data on marine ecoregions to a set of observations points. For the most part it worked pretty well, but out of our 2million+ points, around 200,000 […]
The Cat(fish)’s MEOW
We look at mapping observations of different marine species globally. It’s been said that we know more about the surface of the moon than we do about our own Earth-bound oceans. I suspect that’s true. The amount of data available once we step off the land and into the briny is quite limited compared to […]
Carnival of Coordinates
We struggle with a point dataset’s coordinate system and delve into UTM. Ah, if only every day could be a carnival at GIS Central…sigh. Rather than a samba to start the day, here’s a fairly common occurrence: a colleague sends me some data in a CSV file and asks me to map them. As usual, […]
Only Connect
We use network analysis to find streamflow gauging stations downstream of phosphorus sampling points In his novel Howards End, E.M. Forster encouraged us to “only connect”. He was talking about connecting the prose and the passion in our lives, to the exaltation of both, but here we’ll talk about connecting sampling sites within a river […]
Nearer my Points to Thee
We use the Near tool to link streamflow gauging stations close to phosphorus sampling points. In a previous post we looked mapping some water quality sampling points using the visual hierarchy. We’ll continue looking at a few aspects of this project over the next few posts and hopefully see some interesting and fun stuff along […]
