Lesson 3: Raster Data Part 2

Episode 12: Reproject Raster Data

In this episode, you’re about to learn more about raster data projections.

Raster Projection

Raster Data Projections

Question about raster projection

What is hillshade?

Raster Projection Pt. 2

Be aware of the typos!

Discussion about gradients

Gradient colors and plot setting

Raster Projection Pt. 3

Raster Projection Pt. 4

Plotting the hillshade

Question about the plot variables

How do we know the variable is called like as it is shown in the code?

Plotting the hillshade pt. 2

Challenge: Compare the CRSS

Challenge Description

Challenge Solution

Tip: Describe()

describe() can also show the CRS projection

Reproject Rasters

Reproject the raster layer using project() function

Reproject Rasters Pt. 2

Checking the extend using ext()

Raster Resolution

Deal with raster resolution

Question about the resolutions

Do the resolutions look okay to you?

Answer to the question

Raster Resolution Pt. 2

Tip: convert before plotting

Convert the layer before using the ggplot

Raster Resolution Pt. 3

Plotting the raster using ggplot

Episode 13: Raster Calculations

In this episode, you’ll learn more about calculating the values within raster layers in R.

Load the Data

The DTM and DSM layers are both needed to be loaded for this episode to calculate the Canopy Height Model (CHM).

Raster Math and CHM

You’ll produce histograms calculating the DTM and DSM differences.

Challenge: Explore CHM Values

Challenge description

Challenge solution

Challenge solution Pt. 2

Challenge solution Pt. 3

Question about the challenge

Is zero included in the min part?

Export a GeoTIFF

writeRaster() function is introduced here.

Question about GeoTIFF

Is there a difference between using extensions of tif and tiff?

Episode 14: Multi-Band Rasters

In this episode you’re going to learn how to work with multi-band raster data.

Start with Multi-Band data in R

Getting started with multi-band data using rast() function.

Question about alpha and fill

When do you use alpha and when do you use fill?

Additional answers to the previous question

Challenge: Raster Data Values

Challenge description

Challenge solution

Raster Stacks

Bring all bands of a multi-band raster

Raster Stacks Pt. 2

What will the data frame look like?

Raster Stacks Pt. 3

Plotting a Three-Band Image

plotRGB() function is introduced

Questions about the image

What do we see in the Black & White image?

Why does plotting one layer take more time than full image?

Should we consider the case letter when writing the plotRGB() function and its arguments?