…And Standing Up Straight
In this post we cover New Zealand’s new gravity-based vertical datum, NZVD2016. Along the way we’ll get familiar with the weirdly wonderful geoid and WGS84. This post follows on from Keeping Our Heads Above Water, hence the title, and has benefited greatly from comments by LINZ’s Geodetic team – thanks! In a previous post we […]
Keeping Our Heads Above Water
In this post we discuss the highs and lows of sea level. So everyone knows where sea level is, right? When we talk about elevation, we usually put it in the context of how far above (or below) sea level something is. Simple, yes? Well….not quite. Sea level is one of those things that’s easily […]
Getting to the Point(s)
In this post we look at how points can be mapped from their raw coordinates in a text file or table. So the GIS Helpdesk got a call last week – a postgrad was having some trouble mapping some points. Ah, it reminds me of that time all those years ago, before I knew about […]
A New Window on the World – ArcGIS Pro
In this post we look at a new application in the ArcGIS suite – Pro. Like most behemoth software applications, ArcGIS is ever changing. There’s a new horse in the ArcGIS stable and it’s probably one that’s worth getting to grips with, especially as the tea leaves seem to point to this as the direction […]
The GIS Detective – Have LiDAR, Will Travel
In this post we’ll see how LiDAR data were used to help understand a tricky problem. So I’ve got a bit of an issue at my house – and here it is: We live out on the Lyttelton Harbour on steep loess soils, which are prone to tunnel gullies – sub-surface channels that develop in […]
Python Scripting with the Field Calculator
This post details how you can use some Python scripting to do if/else statements in the Field Calculator. If the title of this post and the intro haven’t put you to sleep already, read on! Perhaps they’ve even piqued your interest! (There are support groups available for this condition.) I was recently contacted by a […]
Fun with Cholera!
This post looks at how data can be symbolised in different ways to make for more effective communication using data from John Snow’s mapping of the cholera outbreak in Soho. Well there’s nothing fun about cholera, really. But there are some important lessons we’ve learned about spatial thinking from cholera, particularly with an outbreak in […]
Cholera, Spatial Thinking and John Snow: Soho 1854
A particularly bad outbreak of cholera in Soho in 1854 led one man to identify contaminated water as the mode of transmission and apply one of the most famous instances of spatial thinking. At a time when the fledgling Canterbury colony was getting itself sorted out, the London of 1854 was a stinking, festering hell-hole. Growing from the tiny […]
LiDAR Data – Thousands of Tiny Luminous Spheres
This post covers the basics of LiDAR data and how very high resolution DEMs can be derived from LiDAR data. With an appropriate nod to The Bats, we’ll cover LiDAR data, which, while sort of luminous but not spherical, are certainly tiny and numerous. Thousands is a HUGE underestimate. LiDAR is a form of remote […]
Getting Consistent Symbology with Layer Files
This post covers how you can get consistent symbology across several layers using layer files. So the good people in ERST310/607 have been doing some fun analysis lately (though they may disagree), getting some high-resolution elevation models from LiDAR data (more to follow on that topic). Using three separate datasets, they’re creating DEMs for three […]
