Raising cattle and farming rice contribute to air pollution by

Raising cattle and farming rice contribute to air pollution by,

Releasing the greenhouse gas methane into the atmosphere

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it