[comment]: # (Set the theme:) [comment]: # (The list of themes is at https://revealjs.com/themes/) [comment]: # (The list of code themes is at https://highlightjs.org/) [comment]: # (Pass optional settings to reveal.js:) [comment]: # (markdown: { smartypants: true }) [comment]: # (plugins:[ RevealHighlight ]) [comment]: # (Other settings are documented at https://revealjs.com/config/) # GIS Analyses using Free and Open Source Software (FOSSGIS) Christina Ludwig, Veit Ulrich October 30, 2024 | Institute of Geography | Heidelberg University
### HGG talks **Winter Term 2024/25 - Lateinamerika: Energie Macht Zukunft** - Next talk: Tuesday 12.11.2024 - **Prof. Dr. Johannes Glückler (Ludwig-Maximilians-Universität München)** - Netzwerken, aber wie? Studien zur Governance von Wasser und Fischerei in Chile - [more info](https://hgg.urz.uni-heidelberg.de/) <center> <img src="img/20241112.jpg" width=800> </center> © J. Glückler
## Agenda 0. Course organization 1. Review FOSSGIS projects 2. Weekly Quiz 3. Review Git 4. GDAL: Geoprocessing in the command line 5. Assignment 2: GDAL
## Course organisation
### Tutorium dates **Tuesday, 11:15 - 12:45 in room 132, Im Neuenheimer Feld 348** - Attendance is optional - Bring your own laptop. See [software setup instructions](./docs/software_setup.md) - You can drop in anytime to **ask questions about the assignments** or get help with technical issues. - If you are not able to attend the tutorial, - have your assignment partner ask them in the tutorium - ask questions Wednesdays after the seminar. - post your questions as GitLab Issues.
### Assignment 1 is due this Friday. - **Set your repo to "private"** on GitLab when forking it or change the settings on GitLab later - Settings - General - Visibility - You can invite your group partner to your repo in the GitLab menu: Manage - Members - For each group **only one submission will be graded** - Both students get this grade. - Please **indicate whose repository should be graded** in this issue under fossgis/home: https://courses.gistools.geog.uni-heidelberg.de/fossgis/home/-/issues/11 - If you don't provide a uni id, one submission will be selected randomly - Who is working with whom/who is alone? - Note: Depending on your parameters for the TWI, your TWI values might differ. That's ok!
### Group project deadlines - **Post your preferred groups in [this issue](https://courses.gistools.geog.uni-heidelberg.de/fossgis/home/-/issues/12) until Nov 19th**. - Form groups of 2 students. Afterwards groups will be assigned randomly. - Short project proposal is due on Dec 10
### Reminder: Course webpage http://fossgis.courses-pages.gistools.geog.uni-heidelberg.de/home/content/intro.html <br> <br> ### Any Questions? Any problems with the QGIS Model Designer?
### Review FOSSGIS Projects https://hackmd.io/@chludwig/S1IqMJ_tw
### Take the weekly Quiz: [pollev.com/christinalud976](https://pollev.com/christinalud976) Link is also on the course website.
## git
### git tracks file changes through *commits* <center> <img src="img/git_tracking.svg" width=800> <img src="img/git_commits_small.svg" width=350> </center>
### *git log* shows all commits of this repository ``` $ git log ``` <center><img src="img/git_log.png" width=1000 ></center> **Note:** You can exit the log by typing "q", if you use the default command line editor *vim*.
### *git status* shows the current state of the repository ``` $ git status ``` <center><img src="img/git_status_1.png" width=1000 ></center>
### A *commit* records file changes within the *repository* Adding new or edited files to the staging area, which will be included in the next commit. ``` $ git add ham.py $ git add spam.txt ``` <center><img src="img/git_status_2.png" width=1000 ></center>
Creating the commit containing the files in the staging area: ``` $ git commit -m "edited ham.py, created spam.txt" ``` <center><img src="img/git_log.png" width=1000 ></center>
### Synchronizing your local commits with a central git repository (e.g. on GitHub) <center><img src="img/git_push_pull_s.svg" width=700 ></center>
### Resources on git Check out the [git pages on the course webpage](http://fossgis.courses-pages.gistools.geog.uni-heidelberg.de/home/content/topics/03_git/git_introduction.html) Watch the tutorial videos: - [How to clone a repository](https://www.youtube.com/watch?v=yfFbOUnbE1Y) - [How to create a commit](https://www.youtube.com/watch?v=kVCLIPHfPDo)
## Learning goals for this week By the end of this week you will be able to * ... explain the purpose of the GDAL library and how it relates to other FOSS GIS tools * ... use GDAL to process geo data in the command line. * ... read and understand the GDAL documentation. * ... explain the terms `environment variable` and `PATH`.
## GDAL
### GDAL/OGR Library <img align="right" height="700" src="./img/gdal_window.png"> * **GDAL:** Geospatial Data Abstraction Library * Translator library for [raster](https://gdal.org/programs/index.html#raster-programs) and [vector](https://gdal.org/programs/index.html#vector-programs) geospatial data formats * Initial release 8 June 2000 * Written in C, C++, Python * License X/MIT * Documentation: [https://gdal.org](https://gdal.org/) * Many GIS applications rely on GDAL, e.g. QGIS, ArcGIS, geopandas (python) * [Software using GDAL](https://gdal.org/software_using_gdal.html#software-using-gdal)
### GDAL can only be used from the command line - but which one? **OSGeo shell:** Special command line (shell) in which you can execute programs which are part of the OSGeo distribution. 1. Open the **command prompt** and execute the command [`gdalinfo`](). 2. Open the **OSGeo shell** and execute the command [`gdalinfo`](). What happens?
### Print the PATH variable 1. Open the **command prompt** and print the environment variable 'PATH'. 2. Open the **OSGeo Shell** and print the environment variable 'PATH'. **On Windows** ``` $ echo %PATH% ``` **On Mac OS / Linux:** ``` $ echo $PATH ``` Compare the outputs. Can you explain now why `gdalinfo` is only available in the OSGeo shell?
### Environment variables Environment variables define the environment a program is executed in. The `PATH` variable, for example, contains all directories in which programs that you call from the command line will be searched.
### Getting started with GDAL Get together in pairs of 2 students and solve the following task by referring the [GDAL documentation](https://gdal.org/). 1. What is the purpose of the commands **gdalinfo** and **ogrinfo**? 2. Apply the commands to two files of the last assignment: - "Copernicus_DSM_10_N46_00_E014_00_DEM.tif" - "study_area_prevalje.geojson" 3. Try to interpret the result.
### Usage The general syntax of any command in the command line is: <br> #### $ command + [optional parameters] + [optional flags] **Example:** `ls ./fossgis -l` <br> * **Command:** Name of the command (e.g. `cd`, `ls`) * **Parameter:** Optional parameter for the command (e.g. `./fossgis`) * **Flag:** Optional boolean parameter (e.g. `-l` (unix) or `/b` (windows)) <br> <br> #### Important: The commands, parameters and flags are always **separated by whitespaces**!
### GDAL Documentation and Tutorials - [GDAL documentation](https://gdal.org/) - **Good tutorials to watch:** - [GDAL Tutorial #1: Introduction + Installation](https://www.youtube.com/watch?v=gkdNvwmoV_E&t=270s) (The "Installation" part is not relevant for you, since you've installed GDAL with QGIS) - [GDAL Tutorial: Full playlist](https://www.youtube.com/watch?v=gkdNvwmoV_E&list=PL4aUQR9L9RFp2OOF3v9V_VEcXFmyLPz7f)
### Assignment 2: GDAL The second assignment is available at: [https://courses.gistools.geog.uni-heidelberg.de/fossgis/fossgis_assignment_02](https://courses.gistools.geog.uni-heidelberg.de/fossgis/fossgis_assignment_02). * Submission deadline is **Tuesday Nov 12 2024** on Gitlab. * **Different pairs** as last assignment: Post your preferred groups [here](https://courses.gistools.geog.uni-heidelberg.de/fossgis/home/-/issues/13) until this Friday 1.11. * Try **not to mix Mac/Linux and Windows users** in the groups for this assignment to avoid compatibility problems when writing scripts. * If you get stuck, **post an issue** rather than wasting your time! Someone will help you.