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Fix PCA tutorial: remove extra spaces and add histogram instructions #107

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Fix PCA tutorial: remove extra spaces and add histogram instructions #107

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12 changes: 10 additions & 2 deletions content/tutorials/remote_sensing_visualization/GRASS_remotesensing.qmd
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Original file line number Diff line number Diff line change
Expand Up @@ -435,7 +435,7 @@ Here, we will explore **principal components analysis** (PCA). PCA mathematicall
Perform a PCA and output the results to the console/terminal and as PCA component maps.

```{python}
i.pca input=landsat8_2024_B2,landsat8_2024_B3,landsat8_2024_B4, landsat8_2024_B5,landsat8_2024_B6,landsat8_2024_B7 output=Flagstaff_landsat8
i.pca input=landsat8_2024_B2,landsat8_2024_B3,landsat8_2024_B4,landsat8_2024_B5,landsat8_2024_B6,landsat8_2024_B7 output=Flagstaff_landsat8
```

#### Python
Expand All @@ -444,7 +444,7 @@ Perform a PCA and output the results to the console/terminal and as PCA componen

```{python}
gs.run_command("i.pca",
input="landsat8_2024_B2,landsat8_2024_B3,landsat8_2024_B4, landsat8_2024_B5,landsat8_2024_B6,landsat8_2024_B7",
input="landsat8_2024_B2,landsat8_2024_B3,landsat8_2024_B4,landsat8_2024_B5,landsat8_2024_B6,landsat8_2024_B7",
output=Flagstaff_landsat8)
```

Expand Down Expand Up @@ -491,6 +491,14 @@ Here is PCA component 1 colored with a **bcyr** (blue-cyan-yellow-red) color tab

Follow the instructions given above for histogram equalization, but pick `bcyr` instead of grey for the color table.

```bash
# Set PCA component 1 to bcyr false color
r.colors -e map=Flagstaff_landsat8.1 color=bcyr

# Reset histogram to grey for subsequent steps
r.colors -e map=Flagstaff_landsat8.1 color=grey
```

Note how areas of different vegetation, soil, and water stand out more clearly than with grey-scale. Try other color tables.
:::

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