Merge pull request #130 from GIScience/dev

main update

content/Modul_1/en_qgis_start.md

@@ -380,6 +380,12 @@ An example of a warning icon while adjusting the parameters of a processing tool
 
 ## Where to find help
 
+
+```{admonition} Connect with us!
+:class: tip
+If you have more questions before or after the training or require assistance, do not hesitate to reach out to us by writing an email to `[email protected]`.
+```
+
 There is a big and vibrant QGIS community online. If you are struggling with a specific function, or have questions on how to achieve GIS operations that are not covered on this platform, you can find help on dedicated QGIS forums: 
 
 - QGIS user forum on stackexchange: https://gis.stackexchange.com/?tags=qgis

content/Modul_2/en_data_sources.md

@@ -29,10 +29,20 @@ up-to-date data available from another source.
 share it and how do you need to cite the data source? Make sure to check the 
 licensing and to follow the respective regulations to avoid difficulties.
 
-
 <!-- ADD: Would be nice to have a wiki page on licensing if possible -->
 
+```{figure} /fig/en_data_sources_examples_cartong.png
+---
+name: data sources examples
+width: 600 px
+---
+The data to create maps or perform GIS analyses can come from various sources (Source: [CartONG]())
+```
+
+
+
 :::{dropdown} Overview of useful data repositories
+:open: 
 
 ### General geodata 
 

content/Modul_2/en_qgis_geodata_concept.md

@@ -73,7 +73,7 @@ represented by a line, a building might be represented by polygon and a tree mig
 name: geometry geodata example 2
 width: 700px
 ---
-Geographic information can be an address and/or GPS coordinates
+Geographic information can be an address and/or GPS coordinates. (Source: BRC)
 ```
 
 - Features are displayed on maps with a geometric representation, but they are made of information organized in tables (see {numref}`geodata example`). 
@@ -85,7 +85,7 @@ Geographic information can be an address and/or GPS coordinates
 name: geodata example
 width: 750px
 ---
-A data table in Microsoft Excel with geographic information
+A data table in Microsoft Excel with geographic information. (Source: BRC)
 ```
 
 {numref}`example_geometric_vs_attribute_view` shows the same dataset displayed both as its geometric representation and as an attribute table. 
@@ -95,7 +95,7 @@ A data table in Microsoft Excel with geographic information
 name: example_geometric_vs_attribute_view
 width: 700 px
 ---
-Each polygon on the left represents one row (feature) on the right. 
+Each polygon on the left represents one row (feature) on the right.  (Source: BRC)
 ```
 
 #### Vector file formats
@@ -105,18 +105,22 @@ The following table gives a short description of commonly used vector file forma
 
 | Filename extension| Name | Description |
 | ----------- | ---------------------- | --------------------------------------------------------- |
-|`.shp`       | Shapefile              | Old but still widely used geodata format. Can only contain one dataset. The file has to consist of at least three different files (.shp, .shx, .dbf)|
-|`.gpkg`      | GeoPackage             | Very versatile geodata format and the new standard for geodata. Can contain multiple datafiles (vector, raster and non-spatial data like tables)|
-|`.kml`       |Keyhole Markup Language | Geodata format for use with [Google Earth]( https://earth.google.com/web/)|
-| `.gpx`      | GPS Exchange Format    |Geodata format for the exchange of coordinates. For example for waypoints of tracks. |
-| `.geojson`  | GeoJSON                | Open data format using Javascript Object Notation (JSON) to store geographic data. Can store multiple type of geometries in one file. | 
+|`.shp`       | Shapefile              | A shapefile is a vector data file format commonly used for geospatial analysis. Shapefiles store the location, geometry, and attribution of point, line, and polygon features. It's a common files format used by most GIS software and online mapping platforms. The format is old but still widely used geodata format. One shapefile can only contain one dataset. A complete shapefile has to consist of at least three different files (.shp, .shx, .dbf)| 
+|`.gpkg`      | GeoPackage             | The new standard for geodata. GPKG files are an open, portable SQLite-based format for storing vector and raster geospatial data, compatible with various GIS platforms on desktop, web, and mobile. Can contain multiple datafiles (vector, raster and non-spatial data such as tables) |
+|`.kml`/`.kmz.`       |Keyhole Markup Language | Geodata format for use with [Google Earth]( https://earth.google.com/web/). KMZ files are compressed versions of KML (Keyhole Markup Language) files used to store geographic data, such as points, paths, and polygons, along with any associated media like images and icons. Commonly used with Google Earth and other mapping software, KMZ files bundle both spatial data and resources in one compact file, making it easy to share interactive maps and visualizations.|
+| `.gpx`      | GPS Exchange Format    | Geodata format for the exchange of coordinates. For example for waypoints of tracks. |
+| `.geojson`  | GeoJSON                | Open data format using Javascript Object Notation (JSON) to store geographic data. Can store multiple type of geometries in one file and is widely compatible with web and mobile applications. | 
+| `.gdb`      | Geodatabase            | Sesigned for efficient data management, spatial analysis, and complex geospatial workflows. Geodatabase files are a proprietary Esri format for storing and managing large volumes of spatial data, including feature classes, tables, and relationships in a structured database. |
 
 
-The most common file formats used in GIS applications are:
-- __Shapefile__: A shapefile is a vector data file format commonly used for geospatial analysis. Shapefiles store the location, geometry, and attribution of point, line, and polygon features. It's a common files format used by most GIS software and online mapping platforms. 
-- __Geodatabase__: Similar to shapefile, it’s ESRI ArcGIS most used file format.
-- __GeoJSON__: Similar to shapefile, but based on JSON. Mostly used in mobile and online applications.
-- __KML/KMZ__: Initially developed to use in Google Earth, KML files are based on the XML standard. They are used in most mobile apps.
+```{note}
+The different file formats have different use cases, as well as advantages or shortcomings. 
+
+- For instance, __GeoJSON__ files cannot store projection info and are conventionally limited to the WGS84 ellipsoid. This makes it difficult to use GeoJSON files in projects where you are using region-specific projections or use projections based on different ellipsoids.
+
+- __Geodatabase__ and __Geopackage__ are, unlike the other formats, databases. In GIS, databases store spatial data in structured, scalable systems that support multi-user access, complex queries, and large datasets, making them ideal for enterprise-level analysis and data management. Files, on the other hand, store data in individual, portable formats like Shapefiles, GeoJSON, or GeoPackage, which are easier to share and use offline but lack advanced querying capabilities and scalability.
+
+```
 
 #### Shapefile structure
 
@@ -127,7 +131,7 @@ A shapefile is a collection of separate files which commonly come in a single fo
 name: shapefile_folderstructure
 width: 400 px
 ---
-__SHP, SHX__ and __DBF__ are the __mandatory__ files that every shapefile must contain to work properly. The SHP is the main file and contains the geometry. 
+__SHP, SHX__ and __DBF__ are the __mandatory__ files that every shapefile must contain to work properly. The SHP is the main file and contains the geometry.  
 ```
 
 
@@ -136,8 +140,7 @@ __SHP, SHX__ and __DBF__ are the __mandatory__ files that every shapefile must c
 Another type of geospatial data is raster data. Raster data consists of cells that are organized into a grid with 
 rows and columns, thus forming a raster. Each cell, or pixel, contains a value which holds information (for 
 example, temperature, or population density). Since raster data consists of pixels, aerial photographs or satellite 
-imagery can also be used as raster data, if they have geographical coordinates (see [georeferencing]()).
-<!-- FIXME: insert georeferencing link --> 
+imagery can also be used as raster data, if they have geographical coordinates (see [georeferencing](/content/Modul_3/en_qgis_georeferencing.md)).
 
 Typical uses for raster data are: 
 
@@ -205,6 +208,13 @@ Raster data can have the following data formats:
 |`.nc`|netCDF|Standard data format for scientific data like speed or temperature. Can be a raster file. Can contain multiple datasets|
 |`.asc`|Esri ASCII Grid files|Old, simple raster file format, always with georeferenced data|
 
+```{admonition} The advantage of geodatabases
+
+Databases such as Geodatabase (`.gdb`) or 
+
+
+```
+
 ----
 
 {numref}`The main geographical data formats` summarizes the different data formats for raster and vector data commonly used in GIS.
@@ -227,8 +237,6 @@ objects of the same type (line, polygon, raster, ...). GIS software displays the
 let's you rearrange the order of these layer, in order to create insightful maps.
 
 
-
-
 By adding different layers, you build your map and can combine information from 
 different sources. With those, you can then perform analyses or adapt the 
 representation by using symbols and colors. 
@@ -324,7 +332,7 @@ name:
 align: center
 name: Import delimited text
 ---
-Import delimited text.
+Import delimited text in QGIS 3.36.
 ```
 
 1. `Layer` -> `Add Layer` -> `Open Delimited Text Layer`.
@@ -347,7 +355,7 @@ name:
 align: center
 name: Import delimited text - file format
 ---
-Import delimited text - file format.
+Import delimited text in QGIS 3.36 - file format.
 ```
 
 4. `Geometry definition`: In this section, you specify which columns of the file 

content/Modul_2/en_qgis_projections.md

@@ -6,8 +6,13 @@
 
 
 An important issue when creating a map of a region, is that it is impossible to create a representation of a sphere 
-on a 2D plane without distorting the map. The transformation of a 3D object onto a flat surface can be done with the help of a __projection__. Over the centuries, cartographers and mathematicians have developed a multitude of different methods to project the earth onto a flat surface. However, it is never possible to correctly represent the world on a flat surface (see the video above). 
-Every projection distorts either the length between two points, the angles between two lines (directions), or the size of an area. A projection can only correctly represent one of these three dimensions. This means, that depending on the projection method, your world map will not represent the size, angles, or distances correctly. 
+on a 2D plane without distorting the map. The transformation of a 3D object onto a flat surface can be done with the 
+help of a __projection__. Over the centuries, cartographers and mathematicians have developed a multitude of different 
+methods to project the earth onto a flat surface. However, it is never possible to correctly represent the world on a 
+flat surface (see the video above). 
+Every projection distorts either the length between two points, the angles between two lines (directions), or the size 
+of an area. A projection can only correctly represent one of these three dimensions. This means, that depending on the 
+projection method, your world map will not represent the size, angles, or distances correctly. 
 
 ```{figure} /fig/en_examples_projections_IBIS.png
 ---
@@ -56,13 +61,21 @@ Comparison Greenland - Africa. Source: [The True Size of](https://www.thetruesiz
 
 In GIS, we project the earth onto a flat coordinate system (hence the name coordinate reference system or CRS). 
 It is crucial that you are aware that your data can be in one CRS and your QGIS 
-project in another CRS. The data and the project should always be the same, or 
-else you will get wrong results! The project CRS is displayed on the bottom right
+project in another CRS. 
+
+The project CRS is displayed on the bottom right
 corner of the [QGIS interface](/content/Modul_1/en_qgis_start.md#overview-of-qgis-interface).  
+Here, you can see the EPSG code. EPSG stands for European Petroleum Survey Group, and it refers to a standardized code 
+system for coordinate reference systems (CRS) and projections. Each EPSG code (e.g., EPSG:4326 for WGS84) uniquely 
+identifies a specific CRS, helping ensure consistency and interoperability in geospatial data across different 
+platforms and applications. 
+
+- __EPSG Codes:__ These are numerical identifiers assigned by the EPSG database to specific coordinate reference systems, making them concise and unambiguous (e.g., EPSG:4326 for WGS84). They provide a standardized way to reference CRS across various GIS applications.
+- __CRS Names:__ These are typically descriptive names for coordinate reference systems (e.g., "WGS 84" or "NAD83"). While names can provide insight into the system being used, they may not be unique or universally recognized, leading to potential confusion without the accompanying EPSG code.
+
 To change the CRS of your data and project, follow the steps explained below.
 The default CRS/EPSG code of every QGIS project is the World Geodetic System 84 
-(EPSG: 4326). This CRS is optimized for world maps. So not perfect for most 
-applications, because we mostly use maps for small areas. 
+(EPSG: 4326). This CRS is optimized for world maps and therefore is not ideal for most humanitarian application, as we need region-specific projections, that provide the least distortion on the scale we wish to represent. 
 
 ```{Tip}
 Choose the projection according to your area of interest. There are special CRS, that have been created to reduce 
@@ -91,7 +104,11 @@ width: 500 px
 The World Geodetic System 1984 (EPSG:4326)
 ```
 
-The WGS 84 is a CRS which consists of an ellipsoid, that resembles the shape of the earth closely. Instead of metrical units of measurements, it uses angular degrees (latitude and longitude). The shape of the Tissot circles is undistorted near the equator, but becomes elongated on the East-West axis the further it gets away from the equator. Unlike the Mercator projection, there is no distortion on the in the North-South direction. As the circles become distorted, we can deduce that the this CRS distorts the angles.
+The WGS 84 is a CRS which consists of an ellipsoid, that resembles the shape of the earth closely. Instead of metrical 
+units of measurements, it uses angular degrees (latitude and longitude). The shape of the Tissot circles is undistorted 
+near the equator, but becomes elongated on the East-West axis the further it gets away from the equator. Unlike the 
+Mercator projection, there is no distortion on the in the North-South direction. As the circles become distorted, we 
+can deduce that the this CRS distorts the angles.
 
 
 ```{figure} /fig/World_equidistant_cylindrical_tissots.png
@@ -113,6 +130,16 @@ characteristic:
 | Rotation | ✅          |  ✅      |  ❌  |
 | Area | ❌             |  ✅           |  ✅   |
 
+Another very important consideration when choosing the Coordinate reference system is that, depending on the ellipsoid and the method used to project the same point can be located at different locations (see {numref}`wrong_CRS_points`). In the figure below, the same point is encoded in 3 different reference systems.  
+
+```{figure} /fig/wrong_CRS.png
+---
+name: wrong_CRS_points
+width: 750 px
+---
+The same point in three different reference systems (Source: HeiGIT).
+```
+
 
 ### Metric and Geographic Coordinate Reference Systems
 
@@ -130,12 +157,12 @@ There are two different types of Coordinate Reference System: __Geographic__ or
 name: problem_distance_geographic_coords
 width: 600 px
 ---
-A geographic representation of the globe. The distance between the meridians converge towards the north and south pole. 
+A geographic representation of the globe. The distance between the meridians converge towards the north and south pole. (Source: HeiGIT)
 ```
 
 ```{caution}
 
-When processing geodata, QGIS always uses the units of measurements of the layer that you are processing.
+When processing geodata, QGIS always uses the units of measurements of the layer that you are processing. This means that if you want to calculate, for example, the distance in kilometers, the layer must be in a metric CRS. You can check the units of measurements of any given layer by <kbd>Right clicking</kbd> on the layer in the layer panel > `Properties` > `Information` > `Coordinate Reference System (CRS)`. 
 
 ```
 

content/Modul_3/en_qgis_data_classification.md

@@ -42,8 +42,26 @@ based on qualitative attributes. These categories don't have any inherent order
 numerical significance: Values or labels are just names or identifiers (in some cases landcover classes can be 
 identified with numbers).
     - Examples: Land cover classes, vegetation types, soil types, amenity type (hospital, church, school, etc.)
+
+    ```{figure} /fig/nominal_scale_examples.png
+    ---
+    name: nominal_scale_example
+    width: 600 px
+    ---
+    Examples for nominal data and their representation (Source: Dickmann (2018) Kartographie, Westermann)
+    ```
+
 - The __ordinal scale__ (ranked data) involves categorizing data, but in this case, the categories have a meaningful order or rank. However, the intervals between the ranks are not necessarily equal or known. Rank order is important: Features can be ranked or ordered from lowest to highest, but the actual difference between ranks isn't measured. You can compare and rank data (i.e., which feature is ranked higher or lower).
     - Examples: Land suitability, hierarchical road network, population size classes, vulnerability classes (e.g. for administrative units)
+
+    ```{figure} /fig/ordinal_scale_example.png
+    ---
+    name: ordinal_scale_example
+    width: 600 px
+    ---
+    Examples for ordinal data and their representation (Source: Dickmann (2018) Kartographie, Westermann)
+    ```
+
 - The __metric scale__ (quantitative data) deals with data that have both order and exact differences 
 between values. Data is represented with precise numerical values and the differences between values are consistent across the scale. Metric data can be further divided into:
     - Interval scale: Numerical data where the difference between values is meaningful, but there is no true 
@@ -52,7 +70,13 @@ between values. Data is represented with precise numerical values and the differ
     point (e.g., distance, area).
     - Examples: Elevation data, distance, area, population data
 
-
+    ```{figure} /fig/interval_ratio_scale_example.png
+    ---
+    name: interval_scale_example
+    width: 600 px
+    ---
+    Examples for metric data and their representation (Source: Dickmann (2018) Kartographie, Westermann)
+    ```
 
 Depending on the type of scale, you will use different methods of classification. Below, we will go over the 
 different types of classification that are available in QGIS, and when to use them for which data. We will also 
@@ -223,7 +247,7 @@ width: 900px
 name:
 align: center
 ---
-Different classifications. Source: HeiGIT  (adapteed from [Axis Maps](https://www.axismaps.com/guide/data-classification)) 
+Different classifications. Source: HeiGIT  (adapted from [Axis Maps](https://www.axismaps.com/guide/data-classification)) 
 ```
 
 ::::{tab-set}
@@ -331,6 +355,5 @@ align: center
 ---
 Graduated classification in QGIS 3.36.
 ```
-
 :::