GIS in Archaeology

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#  GIS in Archaeology

##  02 - Working with QGIS

###  Martin Hinz

####  Institut für Archäologische Wissenschaften, Universität Bern

02/10/24
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based on [Datapolitan-Training/qgis-training](https://github.com/Datapolitan-Training/qgis-training).

You can download a [pdf of this presentation](https://berncodalab.github.io/gia/lectures/02/gis_in_archaeology_02.pdf).
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#Let's Get Started
1. [Click this link](https://github.com/BernCoDALab/gia/raw/main/lectures/01/data/points.zip) and download the file to your desktop
2. Unzip the file
3. [Click this link](https://github.com/BernCoDALab/gia/raw/main/lectures/01/data/background.tiff) and download the other file also to your desktop
3. Open QGIS

![](images/qgis_launch.png)

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## Layers

![img-full](data:image/png;base64,#images/map1.png)
#### Image Source: http://www.geocontrolling.com/co-je-gis.htm

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# Layer Ordering
--

+ Layers on top are drawn on top
--

+ Just drag and drop within the Layers Panel to change order
--

+ Try it now
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## Shapefiles
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+ Basic file for storing map elements
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+ Stores spatial data, like points, lines, and polygons
--

+ Multiple files comprise a "shapefile"

![img-center-80](data:image/png;base64,#images/file_struct1.png)

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## Shapefiles

![img-center-80](data:image/png;base64,#images/file_struct1.png)
--

+ .shp—The main file that stores the feature geometry
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+ .dbf—The dBASE table that stores the attribute information of features

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## Shapefiles

![img-center-80](data:image/png;base64,#images/file_struct1.png)

+ .prj—The file that stores the coordinate system information
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+ .shx—The index file that stores the index of the feature geometry

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## You might also see
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+ .cpg—Identifies the character set to be used
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+ .sbn and .sbx—The files that store the spatial index of the features

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## Shapefiles

+ Have a few limitations
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+ One geometry type (Point, Line, Polygon) per shapefile
--

+ So sometimes you end up with this:
![img](data:image/png;base64,#images/file_struct2.png)
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## Overview of GeoPackage

.pull-left[
* What is GeoPackage?
	*	A data format for geographic information systems (GIS).
	*	Platform-independent, open, and standards-based.
	*	Uses an SQLite database to store both raster and vector data.
* Key Features:
	*	Single file for easy data sharing and use.
	*	Efficient, especially for mobile and offline environments.
	*	Supports extensions for flexibility (OGC-approved and custom extensions).
* Why Use GeoPackage?
	*	Lightweight and portable.
	*	Facilitates easy data management and spatial queries.
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![img](data:image/png;base64,#images/geopkg.png)
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## GeoPackage vs. Shapefiles

1. **File Structure:**
   - **GeoPackage:** Single file (SQLite-based).
   - **Shapefile:** Requires multiple files (.shp, .shx, .dbf, etc.).

2. **Data Handling:**
   - **GeoPackage:** Stores both vector and raster data (multiple geometry type per file possible)
   - **Shapefile:** Vector data only.

3. **Efficiency:**
   - **GeoPackage:** Compact, better suited for mobile/offline use.
   - **Shapefile:** Larger, more fragmented.

4. **Attributes:**
   - **GeoPackage:** Supports larger field names and Unicode.
   - **Shapefile:** Limited field length and ASCII-only.

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## Attribute Table (Right click on layer)
![:width 90%](data:image/png;base64,#images/open_attribute_table.png)
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## Attribute Table

.pull-left[
### Table View 
![img](data:image/png;base64,#images/attribute_table_tableview.png)
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### Form View
![img](data:image/png;base64,#images/attribute_table_formview.png)
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## Shapefiles and Attribute Tables
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+ Column names can only be letters, numbers, and underscores "_"
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+ Column names can only be ten characters long

![:width 70%](data:image/png;base64,#images/attribute_table_tableview.png)
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# Let's add another layer

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## Going out in Bern
+ [Download the data](https://github.com/BernCoDALab/gia/raw/main/lectures/02/data/going_out_in_bern.zip) to your desktop
+ Unzip the file
+ Open in QGIS

![:width 70%](data:image/png;base64,#images/going_out_in_bern_1.png)
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## Going out in Bern

![:width 90%](data:image/png;base64,#images/going_out_in_bern_2.png)

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# Filter and Query
+ We can filter the points based on the values in the attribute table

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# Filter and Query
+ Right-click on the layer and select "Filter" to open the Query Builder

![:width 75%](data:image/png;base64,#images/filter1.png)

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# Filter and Query
![:width 75%](data:image/png;base64,#images/filter2.png)

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# Filter and Query
![:width 50%](data:image/png;base64,#images/filter3.png)
--
![:width 50%](data:image/png;base64,#images/filter4.png)

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# Filter and Query
![:width 75%](data:image/png;base64,#images/filter5.png)

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# Filter and Query
![:width 75%](data:image/png;base64,#images/filter6.png)

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# We can also filter by multiple conditions

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# Filter and Query - Multiple Conditions
![:width 50%](data:image/png;base64,#images/filter7.png)
--
![:width 50%](data:image/png;base64,#images/filter8.png)

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# Filter and Query - Multiple Conditions
![:width 75%](data:image/png;base64,#images/filter9.png)

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# Zoom to Layer
![:width 50%](data:image/png;base64,#images/zoom_to_layer1.png)
--
![:width 50%](data:image/png;base64,#images/zoom_to_layer2.png)

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# Zoom Selection
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+ Select the zoom on the toolbar

![img-right-30](data:image/png;base64,#images/zoom_box.png)
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+ Draw a box around the area you want to zoom into
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+ Click the icon to return to the previous map extent

![img-right-30](data:image/png;base64,#images/extent_box.png)

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# Pan Map
+ Select the hand tool to pan around the map

![img-center-30](data:image/png;base64,#images/hand.png)

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# Exporting Data
![:width 50%](data:image/png;base64,#images/export1.png)
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![:width 50%](data:image/png;base64,#images/export2.png)
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# Your Turn
+ Filter according to your own criteria
+ Try and find something interesting
+ Change the style of the point, either to a different shape, color, or icon
+ Export your selection as a new shapefile

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## CSV-Files
+ General (textbased) spreadsheat format

+ simple and robust

+ human readable (kind of)

--
![:width 100%](data:image/png;base64,#images/csv1.png)

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## CSV-Files

+ Perfect for data exchange between Spreadsheet (Excel) and GIS

![:width 50%](data:image/png;base64,#images/csv1.png)![:width 50%](data:image/png;base64,#images/csv2.png)

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## CSV Import - Bicycle Rental
+ [Download the data](https://github.com/BernCoDALab/gia/raw/main/lectures/02/data/bicycle_rent.csv) to your desktop

![:width 50%](data:image/png;base64,#images/csv1.png)![:width 50%](data:image/png;base64,#images/csv2.png)

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## CSV Import - Bicycle Rental

Load Text Layer

![:width 75%](data:image/png;base64,#images/csv_import1.png)
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## CSV Import - Bicycle Rental

Set coordinate columns

![:width 50%](data:image/png;base64,#images/csv_import2.png)
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## CSV Import - Bicycle Rental

Set coordinate columns

and Coordinate Reference System <- We will explain this in a bit!

You can also access more detailed Coordinate Reference settings.

![:width 50%](data:image/png;base64,#images/csv_import3.png)![:width 50%](data:image/png;base64,#images/csv_import4.png)

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# So what is a Coordinate Reference System?

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# Projections
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+ No one's favorite part of GIS
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+ But a necessary part of it nonetheless
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+ Convert points on the 3-dimensional Earth (**latitude** and **longitude**) to x and y coordinates on a 2-dimensional map

![img-center-85](data:image/png;base64,#images/projections-orange.jpg)

[Digital Coast Geozone](https://geozoneblog.wordpress.com/2012/05/22/happy-birthday-mercator/)

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# Projections
+ Every projection distorts some part of your map

![:width 40%](data:image/png;base64,#images/projections-faces.png)

[FlowingData](http://flowingdata.com/2014/01/13/map-projections-illustrated-with-a-face/)

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# Mercator Projections
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+ A common map projection
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+ Makes geometries near poles look bigger than geometries near the equator
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![:width 40%](data:image/png;base64,#images/mercator.gif)

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# Projections Matter
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+ These circles are all the same size on the globe:

![:width 45%](data:image/png;base64,#images/projections-tissot-mercator.png)
[Progonos](http://www.progonos.com/furuti/MapProj/Normal/CartProp/Distort/distort.html)

+ Conformal map projection (Winkeltreu)

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# Projections Matter
+ As are these:

![img-center-60](data:image/png;base64,#images/projections-tissot-mollweide.png)
[Progonos](http://www.progonos.com/furuti/MapProj/Normal/CartProp/Distort/distort.html)

+ Equal-area projection (Flächentreu)

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# Projections Matter
+ And these:

![:width 45%](data:image/png;base64,#images/projections-tissot-oblique-mercator.png)
[Progonos](http://www.progonos.com/furuti/MapProj/Normal/CartProp/Distort/distort.html)

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# Projections Matter
![:width 80%](data:image/png;base64,#images/projections.png)

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# Projections

+ For the most part we will work in **WGS 84** (latitude and longitude)
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+ In Switzerland, we use a more accurate projection **CHTRS95: Swiss Terrestrial Reference System 1995** that is identical with the european system **ETRS89**.

+ You might also find 'Schweizer Landeskoordinaten' (CH1903) or Landesvermessung 1903 (LV03)

![:width 40%](data:image/png;base64,#images/image.STP_BezugsrahmenLV95.png)
###### Source: https://www.swisstopo.admin.ch/de/wissen-fakten/geodaesie-vermessung/bezugsrahmen/lokal/lv95.html
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# Projections
+ Identified by unique IDs (**EPSG**) that make it easier to talk about them

+ EPSG: European Petroleum Survey Group Geodesy (it was introduced, because Oil companies were annoyed by the incredible number of different systems)

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+ WGS 84 is referred to as **EPSG:4326**

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+ Google Maps and other online sources often uses WGS 84 / Pseudo-Mercator (**EPSG:3857**)

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+ CHTRS95 is referred to as **EPSG:2056**

## Remember these three and you should be set

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# Back to Adding CSV Data

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# Adding CSV Data
![:width 40%](data:image/png;base64,#images/add_csv6_box.png)

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## CSV Import - Bicycle Rental

Bicycles added.

![:width 75%](data:image/png;base64,#images/csv_import5.png)

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# What We've Covered
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+ Adding, styling, and labeling data in QGIS
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+ Projections
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+ Querying features

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# Homework
+ Add the files you can download from the homework page to QGIS (note: the projection epsg is in the filename)
  + background_4326.tif
  + cities_2056.csv
  + lakes_3857.gpkg
+ Style as you like
+ Send me a screenshot

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# Any questions?

![:width 20%](data:image/png;base64,#images/agony_island.png)

.caption[Source: https://www.instagram.com/sadtopographies]

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You might find the course material (including the presentations) at

https://github.com/BernCoDALab/gia

You can see the rendered presentations at

https://berncodalab.github.io/gia

You can contact me at

<a href="mailto:martin.hinz@unibe.ch">martin.hinz@unibe.ch</a>
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