Amara West project blog

Icon

Investigating life in an Egyptian town

Amara West 2013: structure from motion in a pharaonic town

Digital elevation model of villa D12.5Susie Green, UCL

This Sunday I photographed the last of the rooms in neighbourhood E13, in the dawn light before the sun rose. In fact we cheated a little that morning: Sarah Doherty and eight of our site workers held a large sheet of tarpaulin, against the strong wind, to keep the sun off the walls for an extra 15 minutes.

Susie photographing a room with some help in removing sunlight

Susie photographing a room with some help in removing sunlight

I have been at Amara West for just over two weeks. My task here is to create a pointcloud and ultimately a 3D model of the houses in E13 using a process called ‘Structure from Motion’. This technique uses a computer programme to find matching points in multiple images of the same subject. These can be triangulated to find the position of the camera and the points in 3D space and from this create an accurate representation of the subject built up from millions of points. The results are similar to those obtained by laser scanning, but without the need for expensive and unwieldy equipment.

One end of the mastaba in house E13.7, built over by later architecture

One end of the mastaba in house E13.7, built over by later architecture

I have been working my way through the town room by room. In order to get the best results, each room must be photographed in diffuse light as the harsh shadows of the sun obscure the details in the mud brick. This usually means I have to work very fast in the half hour before the sun rises. On the day of the big sandstorm, I could work all morning, as the airborne sand softened the sun’s rays. Saturday granted us an hour of cloudy sky: the first cloud I have seen in two weeks.

One end of the mastaba in house E13.7, built over by later architecture

One end of the mastaba in house E13.7, built over by later architecture

Most of my processing will be done back in London, but I have carried out some tests here to make sure everything is working properly. One of these is to bring together the two halves of the low bench (mastaba) in house E13.7 and virtually remove the later wall that cuts it in half. This allows us to see the mastaba and gain a sense of its size and proportions – it is unusually long for a mastaba in a pharaonic house.

Digital elevation model of villa D12.5, with reconstruction of kite camera positions (Produced in Meshlab)

Digital elevation model of villa D12.5, with reconstruction of kite camera positions (Produced in Meshlab)

The ‘Structure from Motion’ process also allows aerial photographs to be used for detailed models of the ground elevation: a large number of photographs can be linked together as a mosaic to create a very high resolution map of the ground, such as with villa D12.5 being excavated outside the walls.

For this reason I have also brought my kite and camera rig to Amara West and I have taken thousands of aerial pictures of the town and surrounding area. I hope to be able to contribute to the understanding of the area and how it related to the Nile when Amara West was inhabited.

Leave a comment or tweet using #amarawest

Follow @NealSpencer_BM on Twitter for updates

Find out more about the Amara West research project
Read posts from previous excavation seasons at Amara West

Filed under: Uncategorized, , , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 106 other followers

%d bloggers like this: