[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/) <style type="text/css"> .reveal p { text-align: left; } .reveal ul { display: block; text-align: left; } .reveal ol { display: block; text-align: left; } .reveal h1, h2, h3, h4, h5 { display: block; text-align: left; } .reveal pre { font-size: 1.1em} </style> # GIS Analyses using Free and Open Source Software (FOSSGIS) Christina Ludwig, Veit Ulrich November 6, 2024 | Institute of Geography | Heidelberg University
# Agenda 0. Course organisation 1. Getting started with GDAL 2. Scripting 3. GDAL: Error messages
# Assignment 2 is due Friday next week, 15.11. - Find your group: [Assignment groups](https://courses.gistools.geog.uni-heidelberg.de/fossgis/home/-/issues/13) - Please add Lars, Christina and me as collaborators to your repository (see settings), so we can see your submission
# GDAL
### 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)
# 1. 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 assignment 1: - "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**!
# 2. Scripting - Automatisation <img src="./img/script_win.png" height="600" >
# Why scripting? ## What are the benefits of automatising GIS analysis? <br> ## Why use scripts instead of QGIS models? <br> <br> ### Disccuss in pairs.
## What are the benefits of automatising GIS analysis? Automatise execution of multiple commands, so - you have less work, - you save time, - you make less mistakes - others know how the data is processed - others can replicate your analysis. - ...
## Why use scripts instead of QGIS models? - More flexibility - Combine different software beyond QGIS tools, e.g. Python, R - More complex analyses and data processing - Process very large data sets - High performance and large data processing on servers without graphical user interface - ...
## Exercise: How to execute batch/shell scripts? Go to the course website: [Topics -> GDAL/OGR -> Scripting](http://fossgis.courses-pages.gistools.geog.uni-heidelberg.de/home/content/topics/04_gdal/scripting.html) 1. Open your command line and move into the folder [.fossgis_assignment_02/scripts]() of your repo for Assignment 2. `cd ./fossgis_assignment_02/scripts ` 2. Execute the `01_metadata` script from the command line using **Windows:** `./01_metadata.bat` **Mac/Linux:** `./01_metadata.sh` **Mac/Linux:** If you get an error message, you might have to make the file executable. To do this run this once, before executing the file: `chmod +x ./01_metadata.sh` 3. Open den `01_metadata` file in a text editor (e.g. Notepad++) and edit the message after the `echo` statement. Execute the script again and see if the message has changed.
# 3. GDAL: Dealing with error messages Get together in groups of 2 students and solve the [exercises on the course webpage](http://fossgis.courses-pages.gistools.geog.uni-heidelberg.de/home/content/topics/04_gdal/error_exercise.html). <img src="./img/gdal_exercise.png" height="600" >