Utilizing Rstudio as an alternative GIS - Revision history

CharlesPianosi: /* QGIS Functions */

2026-10-10T07:12:09Z

QGIS Functions

2026-10-10T07:08:13Z

Hillshade

2026-10-10T07:07:56Z

Aspect Map

2026-10-10T07:07:29Z

QGIS Functions

2026-10-10T06:31:09Z

Aspect Map

2026-10-10T06:30:50Z

Aspect Map

2026-10-10T06:30:15Z

Aspect Map

2026-10-10T06:29:55Z

Aspect Map

2026-10-10T06:25:29Z

Laplacian Filter

2026-10-10T06:24:35Z

Added section: Aspect, to supplement lost data from laplacian filter section

@@ Line 96: / Line 96: @@
  qgis_search_algorithms(algorithm="clip")
 After running this line you will see a list of 7 clipping tools that have been displayed in the console.
-[[File:QGIS R algoSearch.png|500px|thumb|none| Figure 7: Clipping algorithms available for use within RStudio]]
+[[File:QGISsearchalgorithmsupdated.png|500px|thumb|none| Figure 7: Clipping algorithms available for use within RStudio]]
 We will select the GDAL clipping function '''gdal:cliprasterbyextent''' and determine which parameters we will need to be able to make use of this function in RStudio. To do this we will use the '''qgis_get_argument_specs()''' function. In order to use this function we need to use the full name of the function which is '''gdal:cliprasterbyextent'''.

@@ Line 200: / Line 200: @@
 Below you can see the output generated from the hillshade as well as the output generated by overlaying the DEM.
-[[File:Hillshade BC.png|500px|left|thumb|none| Figure 13: Hillshade raster of the original Canadian DEM.]]
+[[File:Hillshade BC.png|500px|left|thumb|none| Figure 15: Hillshade raster of the original Canadian DEM.]]
-[[File:HillElev BC.png|500px|center|thumb|none| Figure 14: Canadian DEM overlaying the hillshade raster.]]
+[[File:HillElev BC.png|500px|center|thumb|none| Figure 16: Canadian DEM overlaying the hillshade raster.]]
 .

@@ Line 177: / Line 177: @@
  plot(aspectmap, col = rainbow(50), main = "Slope Aspect in degrees")
-[[File:SlopeAspectMap1.jpeg|700px|thumb|none| Figure 9: Aspect map generated in R.]]
+[[File:SlopeAspectMap1.jpeg|700px|thumb|none| Figure 13: Aspect map generated in R.]]
@@ Line 186: / Line 186: @@
  plot(aspectcolours, col = c("black", "yellow", "grey", "orange", "black"), main = "Slope Aspect in Degrees")
-[[File:AspectSlope2.jpeg|700px|thumb|none| Figure 9: Aspect map generated in R, with customized symbology.]]
+[[File:AspectSlope2.jpeg|700px|thumb|none| Figure 14: Aspect map generated in R, with customized symbology.]]
 The above code allows us to select which directions get which colours. We can also alter the angle and number of directions by adding or removing breaks or by changing the values.

@@ Line 95: / Line 95: @@
  '''#Searches for functions which contain the keyword 'clip''''
  qgis_search_algorithms(algorithm="clip")
-After running this line you will see a list of 11 clipping tools that have been displayed in the console.
+After running this line you will see a list of 7 clipping tools that have been displayed in the console.
 [[File:QGIS R algoSearch.png|500px|thumb|none| Figure 7: Clipping algorithms available for use within RStudio]]
@@ Line 105: / Line 105: @@
 Now that we know how to search for the functions we would like to use we can go on to utilize these functions to analyze DEM files.
 == Raster to Vector ==
 The first algorithm we will investigate is '''gdal:polygonize'''. This algorithm takes a raster image and converts its features into polygons. In order to use this function we will need to determine the parameters for: input, field, and output. The '''qgis_run_algorithm()''' function takes in the desired algorithm as well as that algorithms parameters, since the output of this function is very large we will be storing the output vector in the temporary files of qgisprocess. This is done leaving out the OUTPUT parameter within the arguments and then calling the '''st_as_sf()''' function on the result of the algorithim.

@@ Line 171: / Line 171: @@
  aspectfile <- file.path(path, "aspectmap.tif")
  qgis_run_algorithm("gdal:aspect", INPUT = canada_dem_clip,BAND = 1, OUTPUT = aspect_file)
  aspectmap <- raster(aspectfile)

@@ Line 176: / Line 176: @@
  plot(aspectmap, col = rainbow(50), main = "Slope Aspect in degrees")
-[[File:SlopeAspectMap1.png|700px|thumb|none| Figure 9: Aspect map generated in R.]]
+[[File:SlopeAspectMap1.jpeg|700px|thumb|none| Figure 9: Aspect map generated in R.]]
@@ Line 185: / Line 185: @@
  plot(aspectcolours, col = c("black", "yellow", "grey", "orange", "black"), main = "Slope Aspect in Degrees")
-[[File:AspectMap2.png|700px|thumb|none| Figure 9: Aspect map generated in R, with customized symbology.]]
+[[File:AspectMap2.jpeg|700px|thumb|none| Figure 9: Aspect map generated in R, with customized symbology.]]
 The above code allows us to select which directions get which colours. We can also alter the angle and number of directions by adding or removing breaks or by changing the values.

@@ Line 167: / Line 167: @@
 [[File:LaplacianFilter update.png|500px|thumb|none| Figure 12: Canadian DEM filtered by the Laplacian algorithm.]]
+== Aspect Map ==
-We can generate aspect maps using the GDAL function in QGIS, with largely the same prcoess as we did for the other maps:
+We can generate aspect maps using the GDAL function in QGIS, with largely the same process as we did for the other maps:
  aspectfile <- file.path(path, "aspectmap.tif")