Battlefield Images, Computer Visualization, and the Study of Cultural Landscapes

Painting by Captain James Hope.

NPS

The Battle of Antietam was the first battlefield of the American Civil War to be extensively covered by cameramen soon after the fighting stopped. Alexander Gardner, working for Mathew Brady, took over 95 photographs in September and October 1862. The landscape-turned-battlefield was also sketched by some of the top newspaper artists of the time, including Alfred Waud, Edwin Forbes, and Frank Schell. Today, Antietam National Battlefield is one of the best preserved mid-nineteenth century rural landscapes left in the Eastern Theatre of the Civil War. For these reasons, Antietam was selected by National Park Service archeologists as an ideal laboratory to experiment with applying computer visualization technologies to the historical and archeological study of cultural landscapes.

The Mumma Farmstead

1862 Mumma farmstead burning.

NPS

During the battle, the Confederates burnt Samuel Mumma's farmhouse, springhouse, and barn to prevent them from being used by Union Sharpshooters. This on-the-spot sketch was done by the Englishmen Alfred Waud.

Alexander Gardner photograph, 1862.

NPS

Two days after the battle, Alexander Gardner took this photograph of the ruins of Mumma's house and springhouse. The National Park Service had several research questions concerning Mumma's Farm. Since no pre-battle images exist of the house, how do the ruins of the 1862 house relate to the configuration of the rebuilt house? And, how do some of the 1862 structures and landscape features, such as the trees, relate to the post-battle farm, and can they be accurately located for archeological investigation?

Creating Wireframe Models

Wireframe rendering of Mumma farmstead.

NPS

A joint National Park Service and URS Greiner field crew took measurements of the Mumma Farm building foundations and of the distances between the buildings. This information was entered into AutoCAD, a computer-aided drafting program, to create a two-dimensional footprint of the site. The field crew also took over 100 photos of the buildings and farmstead.

Next, the AutoCAD computer map and contemporary photos of the Mumma buildings were entered into a software program called 3-D Builder that constructed a three-dimensional wire-frame model of the 1997 farmstead -- this view was taken from a portion of the 3-D Studio Max Screen.

Alexander Gardner photograph, 1862.

NPS

The 1862 Gardner photo was then scanned into the computer and a wire-frame geometrical model was created. Importing the wire frame geometry of the Gardner photo into 3-D Builder, the common points between the 1862 and 1997 landscapes were established and an estimated camera focal length was entered to calculate the 1862 position of Alexander Gardner's camera.

Using 3-D Studio Max, the 1862 Gardner photo was imported and used as a background. The newly created models from 3-D Builder were imported and the 3-D Studio Max camera was placed using the interpolated camera position supplied by 3-D Builder. The 3-D Builder software allowed the researchers to align the wire frame geometry of those portions of the 1997 buildings common to the 1862 Gardner photo.

Field Procedures

Researchers isolate location where Gardner took his 1862 photo.

NPS

With the Gardner camera position refined, it was now possible to inspect the composite image visually. Using 300-foot tape measures, the field crew was able to triangulate from enough extant building corners to locate Gardner's 1862 camera position.

Present-day location isolated for historic photo.

NPS

On this spot, the crew set up a video camera and connected it to a laptop computer. Adobe Photoshop allowed Senior Animation Specialist Jeff Coleman of URS Greiner to align the field image to the 1862 Gardner photo and compare them directly

Present-Day and Historic Photo Overlay

Left image
This is the 1997 video image taken from Gardner's 1862 photo position.
Credit: NPS

Right image
This photograph shows the 1862 Gardner photo with the 1997 video image overlaid and aligned.
Credit: NPS

Overlay with 1862 Features

Left image
Smokehouse overlaid.
Credit: NPS

Right image
Tree added.
Credit: NPS

The 1862 smokehouse and the large tree were cut out from the Gardner photo and brought into the 1997 video image, allowing the National Park Service to establish their locations relative to existing structures.

Archeologists can now easily locate both the 1862 smokehouse and the large tree using standard archeological excavation techniques.