FSP Cost Surface CartoCSS - How to colorize a raster to store cost values in the blue band of a 1-band raster. Make sure to use the band="1" in the Advanced textbox of the raster properties.

gistfile1.txt

Map {
  background-color: #b8dee6;
}

#countries {
  ::outline {
    line-color: #85c5d3;
    line-width: 2;
    line-join: round;
  }
  polygon-fill: #fff;
}

#clipped3class {
  raster-opacity:1;
  raster-scaling:gaussian;
  raster-colorizer-default-mode: exact;
  raster-colorizer-default-color: transparent;
  raster-colorizer-epsilon:0.41;
  raster-colorizer-stops:
    stop(1,rgb(0,0,1)) //Roads are 1
    stop(10,rgb(0,0,20)) //Dirt is 10
    stop(100, rgb(0,0,200)) //100 is Water
    stop(101, rgb(0,0,1)) //101 is Bridges
}