Cultural Resource Monitoring and Documentation

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The famous Laetoli footprints were made by a human ancestor 3.56 million years ago in the Rift Valley of Tanzania and are the earliest fossil evidence of bipedalism in our ancestors.  The trail of 70 tracks found in 1976, are believed to correspond to an Australopithecus afarensis. The tracks were covered for protection after initial investigations.  At the request of the Tanzanian government a partial re-excavation of the site was conducted in February of 2011 to evaluate the preservation of the buried footprint trail and to get samples for further scientific studies. The information gained from the re-excavation will be used to develop a state-of-the-art museum that will cover the site.

Photogrammetric specialists from the BLM were part of the interdisciplinary team of scientists that worked at the site during the re-excavation. Close-range digital photogrammetry is a no contact prodcedure that produces a high accuracy 3-dimensional digital reconstruction of a subject using a sequence of overlapping photographs. This method is excellent for remote field locations as it requires only a digital camera of appropriate resolution. The photographs are processed in multi-view matching software which generates a very dense “cloud” of data.

Ancient footprints in the Rift Valley of Tanzania reconstructed with photography.

Ancient footprints in the Rift Valley of Tanzania reconstructed with photography.

The photogrammetric process uses a digital SLR camera to capture a series of photographs that overlap each adjacent photo by approximately 65%.  The photos are utilized to derive accurate and measurable information about the surface photographed. Products of the photogrammetric process include a composite image map of the exposed footprint surface at a resolution of less than one millimeter, a detailed topographic map of the surface, a 3D color coded representation of the surface,and virtual visualizations of the footprint surface.