How to get rayshaded

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# How to get rayshaded
## 😎
### Nathan ‘Nate’ Day
### 2019-03-06

---

class: center

# Rayshade yourself

[@rayshaderbot](https://twitter.com/rayshaderbot)

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# 5 Steps to Shade

.large[
1. Find a elevation map
2. Read that map into R
3. Convert it to raster
4. Convert it to matrix
5. 😎
]

---

# 1) Find an elevation map

The US government has got you (at least on this)

[National Map App](https://viewer.nationalmap.gov/basic/)

Download the elevation as IMG format

```r
img_file <- "~/Downloads/USGS_NED_13_n38w080_IMG/USGS_NED_13_n38w080_IMG.img"
```

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# 2) Read that map into R

Be careful, they're big fellas

```r
library(rgdal)
GDALinfo(img_file)
```

```
## rows        10812 
## columns     10812 
## bands       1 
## lower left origin.x        -80.00056 
## lower left origin.y        36.99944 
## res.x       9.259259e-05 
## res.y       9.259259e-05 
## ysign       -1 
## oblique.x   0 
## oblique.y   0 
## driver      HFA 
## projection  +proj=longlat +ellps=GRS80 +towgs84=0,0,0,-0,-0,-0,0 +no_defs 
## file        ~/Downloads/USGS_NED_13_n38w080_IMG/USGS_NED_13_n38w080_IMG.img 
## apparent band summary:
##    GDType hasNoDataValue   NoDataValue blockSize1 blockSize2
## 1 Float32           TRUE -3.402823e+38         64         64
## apparent band statistics:
##      Bmin    Bmax    Bmean      Bsd
## 1 118.096 1293.38 394.8112 190.6556
## Metadata:
## BandDefinitionKeyword=NONE 
## ConfigKeyword= 
## DataType=Elevation
```

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# 2b) Read *a small chunk of* that map into R

Use `offset` and `region.dim` to subset

```r
gdal <- readGDAL(img_file,
                 region.dim = c(1000,1000)
                 )
```

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# 3) Convert to raster

```r
library(raster)

rastr <- raster(gdal)
```

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# 4) Convert to matrix

```r
dat <- extract(rastr,
               extent(rastr),
               buffer = 1000
               )

mat <- matrix(dat,
              nrow(rastr),
              ncol(rastr)
              )
```

---

# 5) 😎

```r
library(magrittr)
library(rayshader)

mat %>%
  sphere_shade() %>% 
  plot_map()
```

![](get_rayshaded_files/figure-html/ray1-1.png)

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# 5b) 😎  🌊    🌓�🌓

```r
mat %>%
  sphere_shade() %>% 
  add_water(detect_water(mat)) %>%
  add_shadow(ray_shade(mat)) %>% 
  plot_map()
```

![](get_rayshaded_files/figure-html/ray2-1.png)

---

# 5c) 😎 🦄

```r
mat %>%
  sphere_shade(texture = "bw") %>% 
  add_water(detect_water(mat), color = "unicorn") %>% 
  plot_map()
```

![](get_rayshaded_files/figure-html/ray3-1.png)

---

# Learn more

Watch the best talk from rstudio::conf 2019
<p><a href="https://resources.rstudio.com/rstudio-conf-2019/3d-mapping-plotting-and-printing-with-rayshader?wvideo=rqe461mc6z"><img src="https://embedwistia-a.akamaihd.net/deliveries/6ae49f2cf01491080771ae662a4ec8c6.jpg?image_play_button_size=2x&amp;image_crop_resized=960x540&amp;image_play_button=1&amp;image_play_button_color=4287c7e0" width="400" height="225" style="width: 400px; height: 225px;"></a></p><p><a href="https://resources.rstudio.com/rstudio-conf-2019/3d-mapping-plotting-and-printing-with-rayshader?wvideo=rqe461mc6z">3D mapping, plotting, and printing with rayshader - Tyler Morgan-Wall</a></p>

[Rayshader on GitHub](https://github.com/tylermorganwall/rayshader)