Showing posts with label tutorial. Show all posts
Showing posts with label tutorial. Show all posts

Tutorial: Using the Quantum GIS Browser

Tutorial updated and moved to

QGIS 1.8 introduced a new standalone application called ‘Quantum GIS Browser’. This is a useful companion tool to QGIS and helpful in managing GIS datasets. ArcGIS users may think of it as an application similar to ArcCatalog. In this tutorial, I will cover some basic use cases of the QGIS Browser.

Tutorial: Using Online Data via WMS in Quantum GIS

Tutorial moved to

Often you need reference data layers for your basemap or to display your results in the context of other datasets. Many organizations publish datasets online that can be readily used in GIS. A popular standard for publishing maps online is called WMS (Web Map Service). This is a better choice for using reference layers as you get access to rich datasets in your GIS without the hassle of downloading or styling the data.

Tutorial: Working with Projections in QGIS

Map projections often cause a lot of frustration when working with GIS data. But proper understanding of the concepts and access to the right tools will make it much easier to deal with projections. In this tutorial, we will explore how projections work in QGIS and learn about tools available for vector and rasters - particularly reprojecting vector and raster data, enabling on-the-fly reprojection and assigning projection to data without projection.

Tutorial: Working with Terrain Data in QGIS

Tutorial moved to

Terrain or elevation data is useful for many GIS Analysis and it is often used in maps. QGIS has good terrain processing capabilities built-in. In this tutorial, we will work through the steps to generate various products from elevation data such as contours, hillshade etc. The Raster menu comes from the GdalTools plugin. If you do not see the options under Raster menu, please follow this tutorial to find and enable the plugin.

Tutorial: Using Tabular Data in QGIS

Tutorial moved to

Not every dataset you want to use comes as a shapefile, or in a spatial format. Often the data would come as a table or a spreadsheet and you would need to link it with your existing spatial data for use in your analysis. For example, you may be working with census data for a country where the data is in a table, csv, excel file, access database table or any other non-spatial format. To map this data, you have to merge this with a shapefile containing boundaries of census tracts. This operation is known as ‘Table Join’ and this tutorial will cover how to carry out table joins in QGIS.

Tutorial: Styling Vector Data in QGIS Using Size-Scale Field

As you saw in this previous tutorial, there are many options available to style vector data in QGIS. But you may have noticed that all the basic method of styling vector layers uses only a single attribute or a single column from the attribute table. Usually GIS data is pretty rich in information and you have more than one useful attribute in your data layer. Presenting two or more of the attributes together can create a very useful map or communicate a powerful story. In this tutorial, we will explore using ‘size-scale field’ option to draw symbols whose area is proportional to an attribute.

Tutorial: Styling Vector Data in QGIS - Basics

Please see Basic Vector Styling for an updated version of this tutorial.

To create a map, one has to style the GIS data and present it in a form that is visually informative. There are a large number of options available in QGIS to apply different types of symbology to the underlying data. In this tutorial, we will explore some basics of styling.

Tutorial: Selecting Multiple Features in QGIS

When working with GIS data, you might want to delete certain features or run your query on a subset of features from a layer. There are many methods available that can help you save time and select a large number of features easily. I will cover some of these in this tutorial.

Tutorial: Setting Up A Working GRASS Environment in QGIS

GRASS is a popular open source GIS toolkit and has a large number of useful raster, vector and terrain tools for GIS analysis. You can use these toolswithin Quantum GIS with the GRASS plugin. Unfortunately, GRASS is fairly unintuitive for beginner GIS users and it can be daunting to use these tools. In this tutorial I will show you how to setup a simple and generalized working environment that will enable GRASS tools to be used within QGIS.

Tutorial: Digitizing in QGIS

Tutorial moved to

Digitizing is one of the most common tasks that a GIS Specialist has to do. Often a large amount of ‘GIS time’ is spent in digitizing raster data to create vector layers that you use in your analysis. Quantum GIS has powerful capabilities to digitize raster data. In this tutorial, we will take some high resolution satellite imagery and digitize it to create a vector polygon layer.

Tutorial: Performing Spatial Queries in QGIS

Tutorial moved to 

Spatial queries are core to many GIS analysis. In ArcGIS, you probably use ‘Select by Location’ all the time. In Quantum GIS, this functionality is available via the ‘Spatial Query’ plugin.
The example I am showing you here is a pretty trivial one, but demonstrates how to do spatial queries. As usual, the data is from Natural Earth public domain dataset. The question we will try to answer is, ‘What cities in Europe are within 10 kms of a river?’. 

Tutorial: Calculating Line Lengths and Statistics

Tutorial moved to 

Here I will show you how to calculate length of each feature in a line shapefile. This is a very useful operation when working with line data and Quantum GIS has a built-in feature that help you easily calculate line length. In the process, I will also show you how to re-project the vector layer to a different projection, enable on-the-fly CRS transformation and also calculate basic statistics on a particular data-field.

Tutorial: Working with Attribute Table - Basic Queries

Tutorial moved to

GIS data has two parts - features and attributes. Attribute Table contains data about each feature. Here I will show you how to carry out some basic operations on the attribute table using Quantum GIS.

The example here contains a point shapefile of populated places around the world. These are from Natural Earth public domain dataset. The task is to find ‘all capital cities in the world that have a population greater than 1000000’.

Tutorial: Using Plugins in Quantum GIS

Please see Using Plugins for an updated version of this tutorial.

Plugins in Quantum GIS add useful features to the software. Plugins are written by QGIS developers as well as other independent users who want to extend the core functionality of the software. These plugins are made available in QGIS for all the users. Here I will show you how to access the official as well as un-official plugin repositories and install these plugins in QGIS.