::::{grid} auto :::{grid-item-card} :class-card: sd-text-center sd-rounded-circle :link: https://giscience.github.io/gis-training-resource-center/english/content/en/intro.html {octicon}`home-fill;1.5em;sd-text-danger` ::: :::: # Exercise 1: Understanding Geodata ## Characteristics of the exercise :::{card} __Aim of this exercise:__ ^^^ The objective of this exercise is to make your first steps in QGIS. Understand the user interface and get to know the layer concept. You will learn to import and display vector data into QGIS and open the attribute table. Furthermore, we will learn to reproject or change the projection of the vector datasets. ::: ::::{grid} 2 :::{grid-item-card} __Type of trainings exercise:__ ^^^ - This exercise can be used in online and presence training. - It can be done as a follow-along exercise or individually. ::: :::{grid-item-card} __These skills are relevant for:__ ^^^ - QGIS-Essentials - Understanding spatial components of datasets - Navigating the QGIS-interface - Managing and manipulating geodata - Performing basic and advanced spatial analyses ::: :::: ::::{grid} 2 :::{grid-item-card} __Estimated time demand for the exercise:__ ^^^ - The exercise takes around 30 to 60 minutes to complete, depending on the number of participants and their familiarity with computer systems. ::: :::{grid-item-card} __Relevant Wiki articles__ ^^^ * [QGIS Interface](../Wiki/en_qgis_interface_wiki.md) * [Geodata Import in QGIS](../Wiki/en_qgis_import_geodata_wiki.md) * [Layer Concept](../Wiki/en_qgis_layer_concept_wiki.md) * [Attribute Table in QGIS](../Wiki/en_qgis_attribute_table_wiki.md) * [Projections](../Wiki/en_qgis_projections_wiki.md) ::: :::: ## Instructions for the trainers :::{dropdown} __Trainers Corner__ ### Prepare the training - Take the time to familiarise yourself with the exercise and the provided material. - Prepare a white-board. It can be either a physical whiteboard, a flip-chart, or a digital whiteboard (e.g. Miro board) where the participants can add their findings and questions. - Before starting the exercise, make sure everybody has installed QGIS and has downloaded __and unzipped__ the data folder. - Check out [How to do trainings?](../Trainers_corner/en_how_to_training.md) for some general tips on training conduction ### Conduct the training __Introduction:__ - Introduce the idea and aim of the exercise. - Provide the download link and make sure everybody has unzipped the folder before beginning the tasks. __Follow-along:__ - Show and explain each step yourself at least twice and slow enough so everybody can see what you are doing, and follow along in their own QGIS-project. - Make sure that everybody is following along and doing the steps themselves by periodically asking if anybody needs help or if everybody is still following. - Be open and patient to every question or problem that might come up. Your participants are essentially multitasking by paying attention to your instructions and orienting themselves in their own QGIS-project. __Wrap up:__ - Leave time for any issues or questions concerning the tasks at the end of the exercise. - Leave some time for open questions. ::: ## Exercise ### Available Data :::{card} :class-card: sd-text-center :link: https://nexus.heigit.org/repository/gis-training-resource-center/Module_2/Exercise_1/Module_2_Exercise_1_Understanding_Geodata.zip __Download all datasets [here](https://nexus.heigit.org/repository/gis-training-resource-center/Module_2/Exercise_1/Module_2_Exercise_1_Understanding_Geodata.zip) and unzip the folder.__ ::: The zip folder includes: | Dataset name | Original title | Publisher | Downloaded from | |:-------------------------------------------------|:------------------------------------------------------|:--------------------------------------------------------------------------|:---------------------------------------------------------------------| | `sle_admbnda_adm0_adm1_gov_ocha.gpkg` (Polygons) | Sierra Leone - Subnational Administrative Boundaries | United Nations Office for the Coordination of Humanitarian Affairs (OCHA) | [HDX](https://data.humdata.org/dataset/cod-ab-sle) | | `sierra_leone_health_HOT.shp` (Points) | Sierra Leone Health Facilities (OpenStreetMap Export) | Humanitarian OpenStreetMap Team (HOT) | [HDX](https://data.humdata.org/dataset/hotosm_sle_health_facilities) | | `sl-airports.csv` (CSV) | Airports in Sierra Leone | Our Airports | [HDX](https://data.humdata.org/dataset/ourairports-sle) | The GeoPackage `Sierra_leone_administrative_boundaries.gpkg` contains administrative information for Sierra Leone at both national and provincial level. Additionally, the shapefile `sierra_leone_health_HOT.shp` provides information on various health facilities within the country, while the `sl-airports.csv` CSV-file offers information on airports. :::{admonition} Folder structure :type: hint Keep your data management clean by creating a [standard folder structure](https://giscience.github.io/gis-training-resource-center/english/content/en/Wiki/en_qgis_projects_folder_structure_wiki.html#standard-folder-structure) on your computer for your QGIS-projects and geodata. The exercise data should be saved in a location where you can easily find them and the corresponding QGIS-project. ::: ### Tasks 1. Open the files you have downloaded in QGIS. - __Unzip the folder__ with the exercise data. - The geopackage (`.gpkg`) and shapefile (`.shp`) can be dragged and dropped onto the map canvas in QGIS. - The .csv file needs to be imported via the layer menu. - Navigate to `Layer` → `Add Layer` → `Add delimited text layer`. A new window will open. Here you can select the file you want to import by clicking on `...` to the right of the __File name__ field at the top. - Navigate to the folder with the exercise files and select `sl-airports.csv`. - Click open. The CSV-import window will update and show you a preview of the CSV-table. - The table contains geographic information. We will need to specify this under __"Geometry Definition"__. - Click on `Point Coordinates` and select `longitude_deg` as your __"X field"__ and `latitude_deg` as your __"Y field"__. - Click add. a new point layer with the airports should appear on your map canvas. :::{figure} ../../../fig/en_3.36_add_csv.png --- width: 500 px name: navigation to add csv layer --- Opening the CSV-import window. ::: :::{figure} ../../../fig/en_delimited_text_screenshot.PNG --- width: 80% name: delimited_text --- Screenshot of the Data Source Manager - Delimited Text to load a CSV file ::: 2. Interact with the map and explore the datasets. Use the zoom tool and move the map. Focus on the scale window and observe how it varies as you zoom in and out. 3. Familiarise yourself with the layer panel (layer list). Show and hide different layers and move layers around in the hierarchy. Give the data layer a meaningful name. :::{Note} Renaming the layer does not affect the data source, such as file names or storage location. ::: 4. Check out the attribute data of the layers by examining the attribute table. 5. Change the projection in the map view to `WGS 84 / Pseudo-Mercator EPSG:3857`. You can do this in the bottom right corner of your QGIS window. :::{Note} This does not change the projection (coordinates) of the files, only the projection of the map view. Verify this by looking at the properties of the point layer. What projection is shown there? ::: :::{Hint} To obtain information about a layer and its projections, double-click on the layer and look for the `Information` section. This section contains general details such as the file name and file path, as well as information about the Coordinate Reference System (CRS) in the respective section. ::: 6. Save the health facility layer in the `WGS 84 / Pseudo-Mercator EPSG:3857` projection. This will change the projection of the file. This can be done by right-clicking on the layer → `Export` → `Save Features As..`. In the pop-up window, select **GeoPackage as the output file format** and **specify the file location and name** by clicking on the three small points. The file can also be given a layer name, which will be displayed when it is loaded into QGIS. Before running this process, the **projection can be changed** by selecting the desired CRS in the designated section. Verify the changed projection by looking at the properties of the newly created layer. :::{figure} ../../../fig/en_ex1_export_layer.PNG --- width: 40% name: export_layer --- Screenshot of the export window. ::: 7. Save your project. 8. Optional: You can add the OpenStreetMap base map via the browser window, under `XYZ Tiles`. :::{Note} Combining layers in different projections with online basemaps (typically have their own projections) can lead to display issues due to [CRS conflicts](https://giscience.github.io/gis-training-resource-center/english/content/en/Module_2/en_qgis_projections.html#how-to-choose-an-appropriate-projected-coordinate-system). When layers have a distinct CRS, they may not align correctly or appear distorted when overlaid with an online basemap. To mitigate these problems, it's advisable to either reproject the layers to match the CRS of the basemap (which is often not applicable) or temporarily remove the basemap before saving the project. This ensures that the map is displayed accurately and avoids potential visual discrepancies caused by CRS inconsistencies. ::: :::{figure} ../../../fig/en_result_geodata_concept_exercise.png --- width: 80% name: en_result_geodata_concept_exercise --- This is how your output could look like in the end. :::