Download QGIS 2.18.14-1 for mac Older LTR version: Download QGIS 2.14 for mac QGIS is a Free and Open Source Geographic Information System. With this software you can create, edit, visualise, analyse and publish geospatial information on Windows, Mac, Linux, BSD (Android coming soon).
Contents
Lesson Goals
In this lesson you will install QGIS software, download geospatial fileslike shapefiles and GeoTIFFs, and create a map out of a number of vectorand raster layers. Quantum or QGIS is an open source alternative to theindustry leader, ArcGIS from ESRI. QGIS is multiplatform, which means itruns on Windows, Macs, and Linux and it has many of the functions mostcommonly used by historians. ArcGIS is prohibitively expensive and onlyruns on Windows (though software can be purchased to allow it to run onMac). However, many universities have site licenses, meaning studentsand employees have access to free copies of the software (try contactingyour map librarian, computer services, or the geography department).QGIS is ideal for those without access to a free copy of Arc and it isalso a good option for learning basic GIS skills and deciding if youwant to install a copy of ArcGIS on your machine. Moreover, any work youdo in QGIS can be exported to ArcGIS at a later date if you decide toupgrade. The authors tend to use both and are happy to run QGIS on Macand Linux computers for basic tasks, but still return to ArcGIS for moreadvanced work. In many cases it is not lack of functions, but stabilityissues that bring us back to ArcGIS. For those who are learning Pythonwith the Programming Historian, you will be glad to know that both QGISand ArcGIS use Python as their main scripting language.
Installing QGIS
Navigate to the QGIS Download page. The procedure is a littledifferent depending on your operating system. Click on the appropriateOperating System. Follow the instructions below.
Mac Instructions
Windows Instructions
QGIS is very simple to install in most versions of Linux. Follow theinstructions on the download page.
Prince Edward Island Data
We will be using some government data from the Canadian province ofPrince Edward Island. PEI is a great example because there is a lot ofdata for free online and because it is Canada’s smallest province,making the downloads quick! Download PEI shapefiles:
Starting Your GIS Project
Open QGIS. The first thing we need to do is set up the CoordinateReference System (CRS) correctly. The CRS is the map projection andprojections are the various ways to represent real world places ontwo-dimensional maps. The default is WGS84 (it is increasingly common touse WGS 84 which is compatible with Google Earth type software), butsince most of our data and examples are created by Canadian governmentswe recommend using NAD 83 (North American Datum, 1983). For more on NAD83 and the Federal Government’s datum, see NRCan’s website. PEI hasits own NAD 83 coordinate reference system which uses a DoubleStereographic projection. Managing the CRS of different layers ofinformation and making sure they are working correctly is one of themost complicated aspects of GIS for beginners. Nonetheless, if thesoftware is setup correctly, it should convert the CRS and allow you towork with data imported from different sources. Select ProjectProperties
You are now set up to work on the tutorial project, but might have a fewquestions about what CRS to use for your own project. WGS83 might workin the short term, particularly if you are working on a fairly largescale, but it will be difficult to accurately work on local maps. Onehint is to learn what CRS or Projections is used for paper maps of theregion. If you are scanning a good quality paper map to use as the baselayer it might be a good idea to use the same projection. You can alsotry searching the internet for the more common CRS for a particularregion. For those of you working on North American projects identifyingthe correct NAD83 for your region will often be the best CRS. Here are afew links to other resources that will help you choose a CRS for yourown project: Tutorial: Working with Projections in QGIS
Building a Base Map
Now that your computer is driving with the right directions, it’s timeto add some information that makes sense to humans. Your project shouldstart with a base map, or a selection of geospatial information thatlets your readers recognize real world features on the map. For mostusers this will be comprised of several ‘layers’ of vector and rasterdata, which can be rearranged, coloured, and labeled in such a way thatthey make sense to your readers and your project’s objectives. Arelatively new feature on many GIS programs is the availability ofpre-fab base maps, but since this technology is under development foropen source platforms like QGIS we will walk through the process ofcreating our own base map by adding vector and raster layers in thismodule. For those who would like to add pre-fab base maps to QGIS, youcan try installing the ‘OpenLayers’ Plugin under Plugins->Manage andInstall Plugins. Select “Get More” on the left. Click OpenLayers andthen click Install plugin. Click OK and then click close. Onceinstalled, you’ll find OpenLayers in the Plugins Menu. Try installingsome of the different Google and OpenStreetMaps layers. At the time ofwriting this module, the OpenLayers plugin (v. 1.1.1) installs but failsto work properly on any Mac using OSX. It appears to work moreconsistently on QGIS running on Windows 7. Give it a try, as we expectit will only get better in the months ahead. Note, however, that theprojection for some of these global maps do not correct on the fly, sothe satellite images might not alway sync up with data projected in adifferent CRS.
Opening Vectors
Vectors defined: GIS uses points, lines, and polygons, also known asvector data. Its first order of work is to arrange these points,lines, and polygons and project them accurately on maps. Points may betowns or telephone poles; lines could represent rivers, roads, orrailroads; and polygons could encompass a farmer’s lot or largerpolitical boundaries. However, it is also possible to attach historicaldata to these geographical places and study how people interacted withand changed their physical environments. The population of townschanged, rivers moved their courses, lots were subdivided, and land wasplanted with various crops.
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This will add a dense map showing the different forest cover in 1935.However, to see the different categories, you will need to change thesymbology to represent the different categories of forest with differentcolours. We will need to know which column of the database tablesincludes the forest category information, so the first step is to openand inspect the attribute table.
An Attribute Table will open. It has a number of categories andidentifiers. Of particular interest is the LANDUSE category whichprovides information on the forest cover in 1935. We will now show youhow to display these categories on the map.
Qgis Download For Windows 10
How To Download Qgis
Note that in the Layers menu you can add and remove the various layerswe’ve added to the map much the same way you did in Google Earth. Clickon the check boxes to remove and add the various layers. Drag and droplayers to change the the order they appear. Dragging a layer to the topwill place it above the rest of the layers and make it the mostprominent. For example, if you drag ‘coastline_polygon’ to the top, youhave a simplified outline of the province along with place names.
Opening Rasters: Raster data are digital images made up of grids.All remote sensing data such as satellite images or aerial photosare rasters, but usually you can’t see the grids in these images becausethey are made up of tiny pixels. Each pixel has its own value and whenthose values are symbolized in colour or greyscale they make up an imagethat is useful for display or topographical analysis. A scannedhistorical map is also brought into GIS in raster format.
Qgis 3.12 Download
You have learned how to install QGIS and add layers. Download pdf files on mac. Make sure yousave your work!
Qgis Software Download
This lesson is part of the Geospatial Historian.
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