3D MODELING

How To

3D Modeling Process

How the project creates its 3D reconstructions for conservation and publication.

  • Rationale

    Three-dimensional modeling plays an increasing role in archaeological research. In conjunction with an array of on-the-ground tools, such reconstructions help form a scientifically accurate, photorealistic record of in-situ remains useful for digital preservation, conservation planning, and publication.

  • Application

    Even sturdy physical objects such as basalt buildings decay over time due to a variety of factors—from design flaws to natural disasters. For example, in early 2014 one of the walls in Umm el-Jimal’s Byzantine Cathedral collapsed due to natural wear. Luckily, in 2010 an Umm el-Jimal Project team had already digitally recorded the wall for 3d reconstruction; without such a model an accurate, archaeologically sound reconstruction of the structure would become nearly impossible.

  • PhotoModeler Scanner

    PhotoModeler Scanner is a software application used to create virtual, three–dimensional models of real–world objects. These objects can be as small as a footprint or as large as an entire building. The project has been refining a workflow based on this software since 2009.

  • Stereophotography

    Applications such as PhotoModeler function by using overlapping photos to determine the relative positions of the subjects in space. Work begins by taking a thorough set of high-resolution digital images from a variety of angles and positions for each wall of the structure in question. More photos generally allow for a more detailed, more accurate model—but the photos need to be consistent in light, contrast, and distance.

  • Control Points & Photo Stitching

    Completed photographs are uploaded into PhotoModeler, which then creates a series of control points matching the overlapping images to each other. These corresponding points allow the software to orient the photos in space and construct an initial, untextured model of the subject structure. This model consists of many points and loosely resembles the wall or structure it represents.

  • Dense Surface Modeling

    The next step is to create a dense surface model (DSM) of the structure. Similar to the way digital photos are actually an assembly of individual pixels, the DSM is essentially a thick cloud of millions of data points. This point cloud is the framework on which the final reconstruction is built; each point represents a specific location in three-dimensional space as well as a color value.

  • Triangulation

    The last phase is to create triangulations in PhotoModeler, which converts the DSM into an actual surface that better reflects the real-world subject. The surface itself is created by connecting the points of the DSM into a mesh of very small triangles reflecting the structure’s surface. The model is then fine-tuned by carefully removing superfluous triangles—such as those representing sky, ground, or irrelevant parts of the structure. The resulting mesh also retains the color values of each point in the DSM, providing a photorealistic texture mimicking the structure’s actual color.

  • Export & Utilization

    The wall or other structure is now ready for export into a variety of other 3D modeling programs for research and visualization. For instance, Umm el-Jimal Project modelers piece individual pieces of walls into whole structures using Maya. Providing that work has been completed carefully, such software also allows researchers to make measurements and statistical calculations as well as virtual walk-throughs, flyovers, and still images suitable for publication.

Virtual Reconstruction Process

The Umm el-Jimal Project, Open Hand Studios, and the Department of Antiquities of Jordan are developing a systematic, low cost method for three-dimensional reconstruction of ancient structures. The method uses photogrammetric software to interpret the location of image pixels in real space from digital photographic images. As a result, by systematically photographing an ancient building it can be recreated as a photorealistic virtual model with sub-centimeter accuracy. Initial subjects of this work are two of Umm el-Jimal's most important buildings, the Cathedral and House XVIII. When complete, these virtual models will:

1. Form an important means of digitally preserving ancient Umm el-Jimal as the site suffers ongoing weathering and natural deterioration.

2. Allow the project to disseminate its results via interactive, immersive virtual environments that are available to students, researchers, and the public anywhere—not only by visiting the site itself.

3. Facilitate ongoing archaeological research into Umm el-Jimal’s architecture, buildings, construction methods, and larger history.

Point cloud closeup

Digital Tools

As an alternative to expensive, laser-based systems, the Umm el-Jimal Project uses PhotoModeler Scanner, Maya, and other cost-efficient software along with professional digital photography equipment to develop its 3D models.

Check out this page's slideshow by two of the project's reconstruction specialists, Madi Goodman and Bill Soohoo, for more details about the team's 3d modeling process.