Rasters

It is just a specific kind of matrix representing data distributed continuously across some spatial extent.

Learning Objectives

In this topic, we dive into raster objects. Rasters are essentially just matrix objects with some extra geospatial meta data added to it. At the end of this section, you should be able to:

1. Create a raster object de novo.
2. Load in raster files from your computer or online.
3. Identify a bounding box for some region within a raster and crop to that extent.
4. Plot rasters using built-in plot() functions as well as the awesomeness of ggplot() + geom_raster().
5. Extract data from rasters for specific points.

Logistics

Here are some supplementary sources for the content herein:

• The Lecture Narrative as a Markdown Notebook.
• Visual Cheat Sheet by Etienne Racine. Some great visual tools for you to understand various raster operations.
• An ArcGIS to Raster Cheat SheetPreview the document. If you are coming to this from ESRI, here are some translations of routines you use in that point-and-click software and how they are implemented in R.
• A Spatial R Cheat Sheet Preview the document from the book Remote Sensing and GIS for Ecologists Edited by Martin Wegmann, Benjamin Leutner, & Stefan Dech [Amazon].

Assessment

Knowledge of the content for each topic is evaluated using interactive data-intensive assessment.