Contours Made Easy
In this post we look at two different ways of creating elevation contours from a DEM. In one we derive and smooth the contour lines and in the other we smooth the DEM first. One of the most common questions we get here at GIS Central is about creating elevation contours. It’s not a difficult […]
Droning on…
This post covers some of the outputs from LU’s new Unmanned Aerial Vehicle, or drone. The university recently acquired a new unmanned aerial vehicle (UAV), or as they’re more commonly known, a drone. It’s an eight-rotor Altus Delta with three sensors: a high-spec Sony camera, a Sequioa multispectral sensor, and a WIRS thermal camera. That’s […]
Turning the Tables on Text
This post demonstrates how to use the field calculator to extract text values from a field and add them to another field. We join our programme already in progress… So here’s the thing – I’ve been doing some more analysis on the proximity of tobacco retailers to secondary schools, focusing on areas within 0 – […]
How to be in two (or more) places at once
Multiple coordinate systems are covered in this post. In these busy, busy times, wouldn’t it be nice to be in more than one place at a time? Good news! You can! In fact you have been ! You’re soaking in it! “How?” you may well ask. All thanks to multiple coordinate systems. This ties in […]
Map Projections 3: The Tour de Topo
This post looks in detail at our own Topo50 series of 1:50,000 scale topographic maps, building upon previous posts about map projections Finally. Some maps (he said in a huff). Having previously covered the concepts and specifics of map projections, we’re now well placed to look in detail at how map projections come into play […]
Map Projections Part 2: The Allegory of the Cave
In this second post on map projections we cover the range of different types of projections. Part 1 gave us a broad overview of different map projections In thinking about map projections I’m reminded of an old story. Now bear with me on this one: in this story, imagine some prisoners, chained in a cave […]
Keeping Your Feet Dry with Mosaic Datasets
Mosaic datasets can be used store and manage a collection of raster grids. We demonstrate this by downloading some high resolution DEMs and the stitch them together in a mosaic dataset. (Updated May 2019 to point out how to fix any problems from the start.) Even as we speak, students in ERST202 are engaged in […]
Don’t Let That Dragonfly Get Away! – Offline Mapping in Vanuatu
Offline mapping provides a way to collect data in the field without an internet connection. In this post we look at how an app is being used to collect dragonfly observations in Vanuatu. Several years back, Milen Marinov was working on his masters degree here. He’s an expert on Odonata species (dragonflies) and as part […]
Map Projections Part 1: Where on Earth are we?
We begin a discussion of the pluses and minuses, highs and lows of map projections in this post. We’ll always have problems flattening out our spheroidal earth onto flat maps. Not that I’m a huge basketball fan but I’d like to give Shaquille O’Neal the benefit of the doubt about claiming the earth is flat […]
A Shady Topic – Hillshade layers
This post looks at hillshade layers – how they are used and created and how our brain interprets them. I had an interesting mapping experience last winter. While taking a break in the lodge at Mt Cheeseman, I was confronted, yes, confronted, by a strange phenomenon. Now I take a fair bit of pride in […]
