Keitel's series, a senior project for his graduate degree program, was funded by a grant from the German Academic Exchange Service.

Keitel's photo series documents the living situations of people living in the slums of Dhaka, arguably the world's most crowded city.

The photos were taken during a two and a half month visit to Dhaka, from early March to mid-May 2012.

Many of the people in these photos moved to the city from the outlying rural regions, part of a sustained population influx that's overwhelmed the city in recent decades.

Keitel carried a pair of battery-powered steady lights throughout the slums to illuminate each shot. The rooms would have been too dark to shoot.

With more than 15 million people living within its 134 square mile footprint, Dhaka's population is squeezed into 115,000 people per square mile.

The photos in Keitel's series walk a line between portraying the colorful variety of living spaces against the poverty and human struggle they represent. The goal was not to effect specific changes, but to encourage viewers to ask questions.

Each shot is part of a trilogy, which Keitel did to document the spaces that were too cramped to encompass without using a wide-angle lens.

"With the rapid growth of the urban areas worldwide," says Keitel, "Grows the number of people who live inside informal settelments. Today, their number amounts to more than a billion people worldwide. This makes them the fastest growing and most unprecedented social class on earth."

Keitel traveled with a guide who also came from the slums. He helped introduce the photographer to the tenants and facilitated access to their homes.

Despite the colorful interiors in the pictures, life for people in Dhaka is very hard. They often face extortion, theft, rape, and other injustices "And yet," says Keitel, "you go to the wedding reception of your neighbors and laugh with your friends."

"The people come to the cities because they can no longer live on the countryside," says Keitel. "Mostly due to natural disasters. They are poorly prepared to live in the city and have no professional training. The path then leads directly into the slums."