Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Eduardo Mattenet Consultant 2013 Navigating with QGIS 1

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines The QGIS Desktop interface Map View Layer List (Table of Contents) Dockable Status bar Toolbar Menu bar Title bar Tools toolbar Tear-off and dockable Navigating with QGIS 2

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Map and Print Composer Views - Map View (data view) -For display, queries, editing, and analysis - Print Composer -For creating map layouts for output Print Composer View Map View (data view) Navigating with QGIS 3

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Map contains: -Data frames -Layers -Map elements - Data frame -Organizes layers -Layers -Represent symbolized spatial data Data frame Layers, data frames, and maps Layers Navigating with QGIS 4

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Managing the Table of Contents (TOC) Drag layers up or down to change display order Smart defaults for layer draw order: point, lines, or polygons Layers draw in the TOC in order, from the bottom up Remove layers Navigating with QGIS 5

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Layers - Reference spatial data sources - Set symbols, labels and other properties - Manipulate through context menu - Layer properties can be saved and shared as a style layer file (.sld) Navigating with QGIS 6

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Group Layers Create New Group Layer Right-click on Data frame > New Group Layer Group Layers: Allow layers with similar thematic content to be grouped as one collection Allow layers with similar thematic content to be grouped as one collection Control when collection layers are drawn (visible) on map Control when collection layers are drawn (visible) on map Useful for managing a collection of layers Useful for managing a collection of layers Group Layers: Allow layers with similar thematic content to be grouped as one collection Allow layers with similar thematic content to be grouped as one collection Control when collection layers are drawn (visible) on map Control when collection layers are drawn (visible) on map Useful for managing a collection of layers Useful for managing a collection of layers Navigating with QGIS 7

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines QGIS Project (.qgs) - Hold layers, data frame, graphics, map elements - Store information in a map document (.qgs) file - No spatial data is stored in the.qgs file. Navigating with QGIS 8

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Adding Layers to Group Layers To add a layer to a group layer: Add New Group Drag and drop layers under new group layer To add a layer to a group layer: Add New Group Drag and drop layers under new group layer CENSUS Group Layer EMS Group Layer Navigating with QGIS 9

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Broken link to datasource Layer with broken link to data sourceLayer with broken link to data source Red typing appearsRed typing appears A layer keeps track of the location of the data source A broken link to a data source may happen for several reasons: Deleted data source Change folder or data source name Corrupted data source A layer keeps track of the location of the data source A broken link to a data source may happen for several reasons: Deleted data source Change folder or data source name Corrupted data source Navigating with QGIS 10

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Fix Broken link to datasource Right-click on Layer Navigate to data directory Navigate to data directory Select Data Source Select Data Source Repeat until no more broken links (red) are fixedRepeat until no more broken links (red) are fixed Navigating with QGIS 11

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Fix Broken link to datasource All layers showing OK Ready to work! Navigating with QGIS 12

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Query Identifying specific features Parish with a population greater than 2,000 and less than 6,000 (6,000 > x > 2,000) Parish with a population greater than 2,000 and less than 6,000 (6,000 > x > 2,000) Identifying features based on conditions Navigating with QGIS 13

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Join Tabular Data One-to-one or many-to-one relationships Must be based on a common field. The names of the common fields need not be identical but the fields must be the same type and content (e.g., text, date, float, etc.) The fields from Source table are appended to the Target layer Joined tables are not permanently connected Navigating with QGIS 14

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Labeling - Label features based on attribute values - Control labeling from Layer properties - Label features based on attribute values - Control labeling from Layer properties Navigating with QGIS 15

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Dynamic label Maptips Navigating with QGIS 16

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Scale-Dependent Display - Layers can be displayed at scale range - Reduces map clutter - Improves drawing speed Navigating with QGIS 17

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Symbology Navigating with QGIS 18

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Changing Symbol properties Navigating with QGIS 19

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Changing Symbol properties Navigating with QGIS 20

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Symbolizing using qualitative values - Features - Categories Navigating with QGIS 21

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Layer Symbology in QGIS Graduated Colors represent quantities on a map by varying colors, as a choropleth maprepresent quantities on a map by varying colors, as a choropleth map values are grouped into classesvalues are grouped into classes each class is identified by a particular coloreach class is identified by a particular color QGIS provide different color ramps to symbolize dataQGIS provide different color ramps to symbolize data Ideal use: features with changing numerical values Navigating with QGIS 22

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Layer symbology in QGIS (cont.) Unique Value represent “Strings” on a map by varying colorsrepresent “Strings” on a map by varying colors values are grouped into classesvalues are grouped into classes each class is identified by a particular coloreach class is identified by a particular color Ideal use: features with changing string / alphanumeric values Navigating with QGIS 23

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Classification Methods Equal Interval divides the range of attribute values into equal-sized sub-rangesdivides the range of attribute values into equal-sized sub-ranges specify the number of intervalsspecify the number of intervals QGIS determines where the breaks should beQGIS determines where the breaks should be Navigating with QGIS 24

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Classification Methods (cont.) Natural Break (Jenks) Classes are based on natural groupings inherent in the dataClasses are based on natural groupings inherent in the data QGIS identifies break points by picking the class breaks that best group similar valuesQGIS identifies break points by picking the class breaks that best group similar values features are divided into classes whose boundaries are set where relatively big changes in values existfeatures are divided into classes whose boundaries are set where relatively big changes in values exist Navigating with QGIS 25

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Classification Methods (cont.) Quantile Uses an equation to divide values into equal-sized subsetsUses an equation to divide values into equal-sized subsets For example, if you have 15 records and five classes, each class will have 3 recordsFor example, if you have 15 records and five classes, each class will have 3 records Each class contains an equal number of featureEach class contains an equal number of feature Navigating with QGIS 26

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Classification Methods (cont.) Standard Deviation show how much a feature's attribute value varies from the mean show how much a feature's attribute value varies from the mean QGIS calculates the mean values and the standard deviations from the mean QGIS calculates the mean values and the standard deviations from the mean class breaks are then created using these values class breaks are then created using these values Navigating with QGIS 27

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Symbolizing using quantitative values Charts symbolize multiple attributes on one map symbolize multiple attributes on one map communicate the relationship among different attributes. communicate the relationship among different attributes. Can bar and pie charts-over features. Can bar and pie charts-over features. Navigating with QGIS 28

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Things to be aware of Deciding which attributes and symbology to use requires some planning. Before you start collecting any GeoSpatial data, you should ensure you know what attributes are needed and how it will be symbolised. It is very difficult to go back and re-collect data if you plan poorly the first time around. Remember also that the goal of collecting attribute data is to allow you to analyse and interpret spatial information. How you do this depends on the questions you are trying to answer. Symbology is a visual language that allows people to see and understand your attribute data based on the colours and symbols you use. Because of this you should put a lot of thought into how you symbolise your maps in order to make them easy to understand. Navigating with QGIS 29

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines What have we learned? Fields can contain numerical, string (any text) and date information The attribute data for a feature can be used to determine how it is symbolised Graduated colour symbology groups the data into discrete classes Continuous colour symbology assigns colours from a colour range to the features based on their attributes Unique value symbology associates each different value in the chosen attribute column with a different symbol (colour and style) If the attribute of a vector layer is not used to determine its symbology, it is drawn using a single symbol only Different classification methods, Equal Interval, Natural Break (Jenks), Quantile, STD Symbolizing using quantitative values. pie chart and text diagrams Navigating with QGIS 30

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Question? Navigating with QGIS 31

Exposure Mapping Assistance Workshop - April Kingstown St. Vincent and the Grenadines Exercise Navigating with QGIS 32