GIS Blog

Data, data everywhere, but what about what I need?

This post outlines the data currently available on our network.

Those of you who have done any work with GIS will know how important the right data are.  Spatial analysis is very much a garbage in-garbage out process so making sure you’ve got good data to start out with is crucial.  Last week’s post was about getting data off the internet; this week’s is about letting you know what data we’ve already got on campus.

All of our data reside on the network, usually referred to as the J: drive (click here to see how to map to the J: drive and make a connection in ArcCatalog).  Once connected we can browse through the data using ArcCatalog:

Catalog

On the right you can see five folders – the Data folder is the important one for today’s post.  Inside that folder all of our datasets can be found, organised in folders by the name of the dataset.  At last count we had over 30 datasets.

With ArcCatalog you can select layers in the left-hand window (the Catalog Tree) and preview them (the map as well as the table) in the Right-hand window, using the Preview tab.  The map or table can be selected at the bottom.

Catalog2

I struggle with finding a way of covering all the data available without putting you to sleep, so I think I’ll just hit the highlights, or the most commonly used datasets.  I’ll break this down by General Data that might used to create decent maps and Specific Purpose Datasets.  Most of these are national scale data collected by various ministries, government departments or CRIs.  At this point you should be taping your eyelids open – not many pretty pictures from here on in.

General Data

  • Administrative_Boundaries – shapefiles of the regions and TLAs
  • Coastline – line and polygon shapefiles of the New Zealand coastline
  • KiwImagery – a selection of imagery from the KiwImage project; multispectral, panchromatic and pansharpened (for you remote sensists out there) – warning: large file sizes ahead.  The Pansharpend folder has gorgeous high resolution images of the 1:50,000 scale toposheets (I would recommend you use the jp2 versions)
  • Orthophotos – a selection of colour orthophotos (images that have been corrected for various distortions) for the North and South Island in either New Zealand Map Grid (NZMG) or Transverse Mercator (NZTM)
  • Postal_Code_Network_2006 – points and polygons of postal code areas
  • SPOT_data – imagery from the SPOT satellite (some imagery is not georeferenced)
  • SpotMaps – Background information on the SPOT data – some nice whole-island images in the SPOTMapsImagery folder (in NZTM)
  • Topoimages – TIF images of the 1:50K and 1:250K topomaps from LINZ.  If you don’t know which map sheet you need, add the topo50 Sheet Index.shp layer and that will tell you which sheet goes where (look at the PRIME attribute to give you the right sheet).  I often add that layer, make the polygons hollow (i.e. no fill colour) and label it withe PRIME attribute.
  • Toposhapefiles – shapefiles of all the features that can be seen on the 1:50K topomaps, so things like roads, rivers, ski lifts, quarries, the list goes on.  Note that there layers are all at the national scale so you probably want to clip out just the portions that you need.  There are some nice, general interest layers for the country in the AWNZ context folder.
  • World_Data – various generic data in Latitude/Longitude

Specific Purpose Datasets

Jeez – where do I start?

  • AgriBase2006 – a polygon layer of self-reported farms from 2006.  Attributes include farm type.  We’re working on getting an updated version of this one.
  • Bank_Peninsula_Wind_Data – a 500 m x 500 m raster grid of average annual wind speeds (m/sec) for Banks Peninsula
  • CensusData – shapefiles and spreadsheets from the 2006 Census
  • Christchurch – a collection of Christchurch specific data including bus routes, contours from post-earthquake (0.5 m intervals!), 2m contours, road, soils and zoning
  • Darfield Earthquake – mostly imagery post-September 2010.
  • Digital_Elevation_Models – North and South Island 25 m x 25 m DEM, plus some hillshade layers.
  • DOC_data – back country huts (not quite sure why we’ve got that…)
  • Freshwater_Ecosystems_of_NZ – this dataset will require a separate post to cover it all, but basically an enormous amount of data related to freshwater across the country – have a nosey.
  • Land Cover Database 2 and 3 – MfE commissioned a regular updating of this layer, which shows vegetation (land cover) across the country based on satellite imagery (mapped at a 1:50K scale).  We’ve now had three versions of this and so can track land cover changes from roughly 2001/02.  Roughly 50+ land cover classes.
  • Land_Environment_of_NZ – 25 m raster grids across the country that looks for areas with common environmental conditions at four levels of resolution.  This layer also needs its own post but have a look at the LENZ_Technical_Guide.pdf for a better understanding of what it’s all about (use Windows Explorer to look in that folder).
  • Land_Resource_Inventory – the grandaddy of NZ’s spatial layers.  The LRI is a polygon layer (1:50K scale) that groups land areas based on five parameters (soil, slope, geology, erosion potential and vegetation, plus a Land Use Classification code with rates the land based on suitability for agriculture.  This folder also contains the Fundamental Soil Layers (fsl) which uses the same polygons but includes soil phyiscal and chemical parameters, including texture.  Look for a separate post on these layers at a theatre near you.
  • Landform_Elements – 25 m raster grid of different landforms, such as ridge, shoulder, valley, footslope, etc.
  • Landuse_maps_2010 – maps changes in land use for the South Island
  • LUCAS_Landuse_Change_Map – Land Use and Carbon Analysis System
  • NZMG_data – there are plenty of people still doing analysis in NZMG so these are some legacy layers (topomaps, toposhapefiles, imagery, among others)
  • River_Environment_Classification – line shapefiles of stream reaches throughout the country, grouper hierarchically on catchment characteristics (climate, source of flow, geology, landcover, network position, valley landform)
  • South Island Climate Data – raster grids of climate parameters (annual and monthly rainfall, temperature, wind speed (500 m grids, so fairly coarse).

Pshew!  Still with me? There were quite of few of those datasets that I’ve not looked at for a while.  This has been a very cursory overview of our available data which probably raises more questions than it answers.  What we really need is a searchable database – I’ll add that to the list of things to do…

I can see lots of possibilities for posts that follow on from this: detail on specific datasets, clipping, other sources of data, projecting into different coordinate systems, among others.  What would you like to hear more about?  What datasets are we missing?

C

• April 10, 2013


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