I am doing a fire ignition danger analysis using this equation that I found in Millington (2012) http://www.jmecology.com/wp-content/uploads/2014/03/33-42-MILLINGTON.pdf
IR = 4H + 3V + 2I – E
H = human presence (i.e. within 30m of a road/trails) V = vegetation I = Illumination E = Elevation
It is based in another paper by Salas and Chuvieco (1994) that I couldn't find. My problem is the illumination raster. I found another link where they give some guidelines in how to create it, but I have not found any other reference. http://ibis.geog.ubc.ca/courses/geob370/students/class06/fire/mce.html
Do you know where can I find information related to how to create this raster?