gt_load_png_as_traffic_raster {googletraffic}

Converts PNG to raster

Description

Converts PNG of Google traffic data to raster and translates color values to traffic values

Usage

gt_load_png_as_traffic_raster(
  filename,
  location,
  height,
  width,
  zoom,
  traffic_color_dist_thresh = 4.6,
  traffic_color_dist_metric = "CIEDE2000"
)

Arguments

filename

Filename of PNG file

location

Vector of latitude and longitude used to create PNG file using gt_make_png()

height

Height (in pixels; pixel length depends on zoom) used to create PNG file using gt_make_png()

width

Width (in pixels; pixel length depends on zoom) used to create PNG file using gt_make_png()

zoom

Zoom level used to create PNG file using gt_make_png()

traffic_color_dist_thresh

Google traffic relies on four main base colors: ⁠#63D668⁠ for no traffic, ⁠#FF974D⁠ for medium traffic, ⁠#F23C32⁠ for high traffic, and ⁠#811F1F⁠ for heavy traffic. Slight variations of these colors can also represent traffic. By default, the base colors and all colors within a 4.6 color distance of each base color are used to define traffic; by default, the CIEDE2000 metric is used to determine color distance. A value of 2.3 is one threshold used to define a "just noticeable distance" (JND) between colors (by default, 2 X JND is used). This parameter changes the color distance from the base colors used to define colors as traffic. For more information, see here.

traffic_color_dist_metric

See above; this parameter changes the metric used to calculate distances between colors. By default, CIEDE2000 is used; CIE76 and CIE94 can also be used. For more information, see here.

Value

Returns a raster where each pixel represents traffic level (1 = no traffic, 2 = medium traffic, 3 = traffic delays, 4 = heavy traffic)

References

Markus Hilpert, Jenni A. Shearston, Jemaleddin Cole, Steven N. Chillrud, and Micaela E. Martinez. Acquisition and analysis of crowd-sourced traffic data. CoRR, abs/2105.12235, 2021.

Pavel Pokorny. Determining traffic levels in cities using google maps. In 2017 Fourth International Conference on Mathematics and Computers in Sciences and in Industry (MCSI), pages 144–147, 2017.

Examples

## Not run: 
## Make png
gt_make_png(location     = c(40.712778, -74.006111),
            height       = 1000,
            width        = 1000,
            zoom         = 16,
            out_filename = "google_traffic.png",
            google_key   = "GOOGLE-KEY-HERE")

## Load png as traffic raster
r <- gt_load_png_as_traffic_raster(filename = "google_traffic.png",
                                   location = c(40.712778, -74.006111),
                                   height   = 1000,
                                   width    = 1000,
                                   zoom     = 16)

## End(Not run)