I've never seen a pig roaster that looks like that. Around here the County Boys make them out of old oil tanks. Not too portable though.
Different region and culture all have different way of roasting a pig.
Here is an article from the Austin Chronicle on the type of pig roaster
@Tony S posted. They call it La Caja China.
Agree with the article that the name La Caja China is hog wash. Chinese BBQ joints usually hang the pigs vertically for roasting.
Per tradition, we usually get a whole roasted pig from the local Chinese BBQ joint when the family get together to celebrate happy occasions.
This is the roasted pig we ordered to celebrate Andrew landing his first job.
Pig in a box, no blanket.