Clarify relationship between body text and figures (#10346)

Author: DelazJ

docs/gentle_gis_introduction/authors_and_contributors.rst

@@ -24,11 +24,11 @@ About the authors & contributors
 |                | the goal of helping people to learn and use opensource GIS software. |
 |                | **Web**: https://kartoza.com **Email**: marcelle@kartoza.com         |
 +----------------+----------------------------------------------------------------------+
-| |lerato|       | Lerato Nsibande –-- Video Presenter. Lerato is a grade 12 scholar    |
+| |lerato|       | Lerato Nsibande --- Video Presenter. Lerato is a grade 12 scholar    |
 |                | living in Pretoria. Lerato learns Geography at school and has        |
 |                | enjoyed learning GIS with us!                                        |
 +----------------+----------------------------------------------------------------------+
-| |sibongile|    | Sibongile Mthombeni –-- Video Presenter. Sibongile lives near        |
+| |sibongile|    | Sibongile Mthombeni --- Video Presenter. Sibongile lives near        |
 |                | Johannesburg with her young daughter. Her goal is to continue her    |
 |                | studies and become a nurse. Working on this project was the first    |
 |                | time Sibongile used a computer.                                      |

docs/gentle_gis_introduction/data_capture.rst

@@ -19,7 +19,7 @@ of a vector feature describes its **shape** and **position**, while the
 etc.).
 
 In this section we will look more closely at the process of creating and editing
-vector data --– both the geometry and attributes of vector features.
+vector data --- both the geometry and attributes of vector features.
 
 How does GIS digital data get stored?
 =====================================
@@ -152,7 +152,7 @@ sample site. So we may end up with an attribute table that looks something like
 Drawing a table like :numref:`table_river_attributes` before you create your vector
 layer will let you decide what attribute fields (columns) you will need. Note
 that the geometry (positions where samples were taken) is not shown in the
-attribute table --– the GIS Application stores it separately!
+attribute table --- the GIS Application stores it separately!
 
 Creating an empty shapefile
 ===========================
@@ -179,15 +179,15 @@ Next you will add fields to the attribute table. Normally we give field names th
 are short, have no spaces and indicate what type of information is being stored
 in that field. Example field names may be 'pH', 'RoofColour', 'RoadType' and so
 on. As well as choosing a name for each field, you need to indicate how the
-information should be stored in that field –-- i.e. is it a number, a word or a
+information should be stored in that field --- i.e. is it a number, a word or a
 sentence, or a date?
 
 Computer programs usually call information that is made up of words or sentences
 '**strings**', so if you need to store something like a street name or the name
 of a river, you should use 'String' for the field type.
 
 The shapefile format allows you to store the numeric field information as either
-a whole number (**integer**) or a decimal number (**floating point**) –-- so you
+a whole number (**integer**) or a decimal number (**floating point**) --- so you
 need to think before hand whether the numeric data you are going to capture will
 have decimal places or not.
 

docs/gentle_gis_introduction/introducing_gis.rst

@@ -18,11 +18,11 @@ on a computer. GIS stands for **'Geographical Information System'**.
 
 A GIS consists of:
 
-* **Digital Data** –-- the geographical information that you will view and
+* **Digital Data** --- the geographical information that you will view and
   analyse using computer hardware and software.
-* **Computer Hardware** –-- computers used for storing data, displaying graphics
+* **Computer Hardware** --- computers used for storing data, displaying graphics
   and processing data.
-* **Computer Software** –-- computer programs that run on the computer hardware
+* **Computer Software** --- computer programs that run on the computer hardware
   and allow you to work with digital data. A software program that forms part of
   the GIS is called a GIS Application.
 
@@ -78,7 +78,7 @@ GIS is a relatively new field --- it started in the 1970's. It used to be that
 computerised GIS was only available to companies and universities that had
 expensive computer equipment. These days, anyone with a personal computer or
 laptop can use GIS software. Over time GIS Applications have also become easier
-to use --– it used to require a lot of training to use a GIS Application, but now
+to use --- it used to require a lot of training to use a GIS Application, but now
 it is much easier to get started in GIS even for amateurs and casual users. As we
 described above, GIS is more than just software, it refers to all aspects of
 managing and using digital geographical data. In the tutorials that follow we
@@ -87,25 +87,27 @@ will be focusing on GIS Software.
 What is GIS Software / a GIS Application?
 =========================================
 
-You can see an example of what a **GIS Application** looks like :numref:`figure_gis_application`.
+You can see an example of what a **GIS Application** looks like in :numref:`figure_gis_application`.
 GIS Applications are normally programs with a graphical user interface that can
 be manipulated using the mouse and keyboard. The application provides **menus**
 near to the top of the window (:guilabel:`Project`, :guilabel:`Edit`, etc.) which,
 when clicked using the mouse, show a panel of **actions**.
 These actions provide a way for you to tell the GIS Application what you want to do.
-For example you may use the menus to tell the GIS Application to add a new layer to the display output.
+For example you may use the menus to tell the GIS Application to add a new layer to the display output, as in :numref:`figure_gis_menus`.
 
+.. _figure_gis_menus:
 
 .. figure:: img/menus.png
    :align: center
 
    Application menus, when clicked with the mouse, expand to show a list of
    actions that can be carried out.
 
-**Toolbars** (rows of small pictures that can be clicked with the mouse) normally
-sit just below the menus and provide a quicker way to use frequently needed
-actions.
+As seen in :numref:`figure_gis_toolbars`, **toolbars** (rows of small pictures
+that can be clicked with the mouse) normally sit just below the menus and
+provide a quicker way to use frequently needed actions.
 
+.. _figure_gis_toolbars:
 
 .. figure:: img/toolbars.png
    :align: center
@@ -115,7 +117,7 @@ actions.
 
 A common function of GIS Applications is to display **map layers**. Map layers
 are stored as files on a disk or as records in a database. Normally each map
-layer will represent something in the real world –-- a roads layer for example
+layer will represent something in the real world --- a roads layer for example
 will have data about the street network.
 
 When you open a layer in the GIS Application it will appear in the **map view**.
@@ -124,64 +126,63 @@ layer to a map view, the layers are overlaid on top of each other. Look at
 figures :numref:`figure_map_view_towns`, :numref:`figure_map_view_schools`,
 :numref:`figure_map_view_railways` and :numref:`figure_map_view_rivers`
 to see a map view that has several layers being added to it.
-An important function of the map view is to allow you to zoom in to magnify,
-zoom out to see a greater area and move around (panning) in the map.
 
 .. _figure_map_view_towns:
 
 .. figure:: img/map_view_towns.png
    :align: center
    :width: 30em
 
-   A map view with several layers being added to it. A towns layer added to the
-   map view.
+   A towns layer added to the map view
 
 .. _figure_map_view_schools:
 
 .. figure:: img/map_view_schools.png
    :align: center
    :width: 30em
 
-   A map view with several layers being added to it. A schools layer added to
-   the map view
-
+   A schools layer added to the map view
 
 .. _figure_map_view_railways:
 
 .. figure:: img/map_view_railways.png
    :align: center
    :width: 30em
 
-   A map view with several layers being added to it. A railways layer added to
-   the map view
+   A railways layer added to the map view
 
 .. _figure_map_view_rivers:
 
 .. figure:: img/map_view_rivers.png
    :align: center
    :width: 30em
 
-   A map view with several layers being added to it. A rivers layer added to the
-   map view
+   A rivers layer added to the map view
 
-Another common feature of GIS Applications is the **map legend**. The map legend
-provides a list of layers that have been loaded in the GIS Application. Unlike a
-paper map legend, the map legend or 'layers list' in the GIS Application provides
-a way to re-order, hide, show and group layers. Changing the layer order is done
-by clicking on a layer in the legend, holding the mouse button down and then
-dragging the layer to a new position. In figures :numref:`figure_map_legend_before` and
-:numref:`figure_map_legend_after` the map legend is shown as the area to the left of the GIS
-Application window. By changing the layer order, the way that layers are drawn
-can be adjusted –-- in this case so that rivers are drawn below the roads instead
-of over them.
+An important function of the map view is to allow you to zoom in to magnify,
+zoom out to see a greater area and move around (panning) in the map. GIS
+software also lets you easily change symbology --- the way information is
+displayed. :numref:`figure_map_symbology` shows the map view after panning to
+the side and changing the symbology of the layers.
 
 .. _figure_map_symbology:
 
 .. figure:: img/symbology.png
    :align: center
    :width: 30em
 
-   GIS Software lets you easily change symbology --- the way information is displayed.
+   A map view after moving around (panning) and changing the symbology
+
+Another common feature of GIS Applications is the **map legend**. The map legend
+provides a list of layers that have been loaded in the GIS Application. Unlike a
+paper map legend, the map legend or 'layers list' in the GIS Application provides
+a way to re-order, hide, show and group layers. Changing the layer order is done
+by clicking on a layer in the legend, holding the mouse button down and then
+dragging the layer to a new position. In :numref:`figure_map_legend_before` and
+:numref:`figure_map_legend_after`, the map legend is shown as the area to the left of the GIS
+Application window. By changing the layer order, the way that layers are drawn
+can be adjusted --- in this case so that rivers are drawn below the roads instead
+of over them.
 
 
 .. _figure_map_legend_before:
@@ -237,16 +238,16 @@ date columns hold **non-geographical data**.
 A common feature of GIS is that they allow you to associate information
 (non-geographical data) with places (geographical data). In fact, the GIS
 Application can store many pieces of information which are associated with each
-place --– something that paper maps are not very good at. For example, our health
+place --- something that paper maps are not very good at. For example, our health
 care worker could store the person's age and gender on her table. When the GIS
 Application draws the layer, you can tell it to draw the layer based on gender,
 or based on disease type, and so on. So, with a GIS Application we have a way to
 easily change the appearance of the maps we created based on the non-geographical
 data associated with places.
 
-GIS Systems work with many different types of data. **Vector data** is stored as
+GIS Systems work with many different types of data. **Vector data** are stored as
 a series of ``X, Y`` coordinate pairs inside the computer's memory. Vector data
-are used to represent points, lines and areas. Illustration :numref:`figure_vector_data`
+are used to represent points, lines and areas. :numref:`figure_vector_data`
 shows different types of vector data being viewed in a GIS application. In the
 tutorials that follow we will be exploring vector data in more detail.
 
@@ -263,7 +264,7 @@ tutorials that follow we will be exploring vector data in more detail.
 the earth and the photographs they take are a kind of raster data that can be
 viewed in a GIS. One important difference between raster and vector data is that
 if you zoom in too much on a raster image, it will start to appear 'blocky' (see
-illustrations :numref:`figure_raster_data` and :numref:`figure_raster_data_zoom`). In fact these
+:numref:`figure_raster_data` and :numref:`figure_raster_data_zoom`). In fact these
 blocks are the individual cells of the data grid that makes up the raster image.
 We will be looking at raster data in greater detail in later tutorials.
 

docs/gentle_gis_introduction/raster_data.rst

@@ -200,7 +200,7 @@ greatly increase the amount of storage needed.
 
 Sometimes using a low spatial resolution is useful when you want to work with a
 large area and are not interested in looking at any one area in a lot of detail.
-The cloud maps you see on the weather report, are an example of this –-- it's
+The cloud maps you see on the weather report, are an example of this --- it's
 useful to see the clouds across the whole country. Zooming in to one particular
 cloud in high resolution will not tell you very much about the upcoming weather!
 

docs/gentle_gis_introduction/vector_attribute_data.rst

@@ -45,7 +45,7 @@ the house pictures in :numref:`figure_house`.
 The geometry of these house features is a polygon (based on the floor plan of the
 house), the attributes we have recorded are roof colour, whether there is a
 balcony, and the year the house was built. Note that attributes don't have to be
-visible things --– they can describe things we know about the feature such as the
+visible things --- they can describe things we know about the feature such as the
 year it was built. In a GIS Application, we can represent this feature type in a
 houses polygon layer, and the attributes in an attribute table (see :numref:`figure_house_gis`).
 
@@ -149,7 +149,7 @@ table.
    | Record 3        | 2001                | Silver              | Yes              |
    +-----------------+---------------------+---------------------+------------------+
 
-Each field in the attribute table contains a specific type of data –--
+Each field in the attribute table contains a specific type of data ---
 text, numeric or date. Deciding what attributes to use for a feature requires some
 thought and planning. In our house example earlier on in this topic, we chose roof
 colour, presence of a balcony and year of construction as attributes of interest.

docs/gentle_gis_introduction/vector_data.rst

@@ -160,7 +160,7 @@ Polygon features are **enclosed areas** like dams, islands, country boundaries
 and so on. Like polyline features, polygons are created from a series of vertices
 that are connected with a continuous line. However because a polygon always
 describes an enclosed area, the first and last vertices should always be at the
-same place! Polygons often have **shared geometry** –-- boundaries that are in
+same place! Polygons often have **shared geometry** --- boundaries that are in
 common with a neighbouring polygon. Many GIS applications have the capability to
 ensure that the boundaries of neighbouring polygons exactly coincide. We will
 explore this in the :ref:`gentle_gis_topology` topic later in this tutorial.
@@ -186,12 +186,12 @@ Editing vector data
 ===================
 
 The GIS application will allow you to create and modify the geometry data in a
-layer --– a process called **digitising** –-- which we will look at more closely
+layer --- a process called **digitising** --- which we will look at more closely
 in a later tutorial. If a layer contains polygons (e.g. farm dams), the GIS
 application will only allow you to create new polygons in that layer. Similarly
 if you want to change the shape of a feature, the application will only allow you
 to do it if the changed shape is correct. For example it won't allow you to edit
-a line in such a way that it has only one vertex –-- remember in our discussion
+a line in such a way that it has only one vertex --- remember in our discussion
 of lines above that all lines must have at least two vertices.
 
 Creating and editing vector data is an important function of a GIS since it is