Relationship between BGGs D_fil and luminosity density field values for (a) red and blue, (b) high and low mass, (c) elliptical and spiral, and (d) high and low D4000 BGGs. Red and blue contours show the two-dimensional density of the separated populations. Red and blue dots show the peaks of BGG distributions in their respective populations. Individual BGGs are shown with grey points. The variation in populations mostly depends on the luminosity density field at BGG locations.