Putting Images in their Place

Ah, Monday morning… One message in the inbox this morning brought up a classic GIS workflow. How do I take potentially useful information in something like a PDF and add it to a map? This brings us to georeferencing and digitising. As an example of that, we’ve been working with Peter Almond to put together […]

Challenging Times – Challenging Patches

We dissect how to approach a challenging spatial problem by relying on some basic levels of analysis. We often get a lot of challenging problems of a spatial nature here in the GIS world. A common thread of these is that they often sound easy at the start but get much more complicated when you […]

Difficulties with Degrees

In this post we resolve the problem with our US data points In a previous post we looked in excruciating detail at some point data in the US. After first establishing that many, if not all, were in the wrong place, the next step was figuring out how to fix this, which meant getting to […]

Degrees of Difficulty

To work through a mapping project a bit of detective work was needed to get data in the right place. GIS Central has recently been involved with some global mapping as part of an Our Land and Water project. This has involved collating a wide range of environmental data covering soils, hydrology, vegetation, terrain and […]

Driven Crazy by OneDrive

Avoid losing precious data by practicing some Zen calm Here are GIS Central we’ve been fielding a lot of calls from frustrated users, along the lines of: “I finished my project last night but when I opened it up this morning, everything was gone!” -Frustrated in Whangarei “That layer I spent hours on doesn’t work […]

Spatial Joins Made Easy

We cover a quick and easy way to do temporary spatial joins When we opened up the mail bag here at GIS Central recently, out popped a request from a colleague: “Do we have a mapping table of LAWA monitoring site names to the regional council site names?”  Perhaps I should decode this a bit […]

Submitted for Your Reference

Setting the reference scale for you maps can make symbology more consistent across scales. Here at GIS Central we’ve been gearing up for some work on Lake Heron Station in near Mt Somers: As a start I thought I would pull together some of the already available data for this project, things like the LCDB, […]

Orderly Streams

Stream order is a way to categorise river reaches by size.  In this post we see how to add stream orders to a derived stream network. As the temperatures warm up, the tramping season has already gotten underway in our house so keen daughter Islay recently dragged me up the short but steep track to Carroll Hut […]

Burning the Streams

Here we talk about how GIS can be used to create catchment boundaries and river lines from elevation data. Far be it from a surface water person like me to advocate for burning streams in any way (we’re not talking about the Cuyahoga River here), but in a geospatial sense it can be a good thing. […]

Zones of Influence

The role of polygon zones in our lives is up for discussion with a zinger at the end. The image above should raise a number of questions.  What am I doing in the middle of a busy street? for one.  And what does busy Barrington Street have to do with anything?  Note a subtle difference […]