Field-based mapping is commonly performed by community NGOs such as Slum Dwellers International, and linked to advocacy for slum dwellers’ recognition and rights. In many cases, the approach is wholly participatory, where organized community members map and enumerate their settlement to gather planning data and catalyze community action.

When field-based mapping is performed by outsiders such as academics or governments, the approach often begins with a review of satellite imagery and identification of potential informal settlements. Field-based mapping is then performed as validation of imagery interpretation with, or without, the involvement of community members.

While field-based mapping strongly represents local context, and reflects both physical and social characteristics of local areas, the approach on its own is extremely time-intensive and difficult to upscale to entire cities and countries. A further complication is that local experts and residents interpret deprivation in different ways, and draw different boundaries around areas of deprivation.