Names questions

i have nested resources to configurate, but i don’t know wich logical
name using for models, examples:
####################################
map.resources :categories do |categories|
categories.resources :categoryphotos
categories.resources :subcategories do |subcategories|
subcategories.resources :subcategoryphotos
end
end
##################
or
##################
map.resources :cats do |cats|
cats.resources :photocats
cats.resources :subcats do | subcats |
subcats.resources :photosubcats
end
end
##################
or
##################
map.resources :cats do |cats|
cats.resources :photoCats
cats.resources :subCats do | subCats |
subCats.resources :photoSubCats
end
end
####################################

What is the best solution for obtain a code slim, logical and simple?
name of child elements is writing after o befor the name of parent?