Engineering & Science Articles

A 3-D imaging technique is presented which pairs high-resolution night-vision cameras with GPS to increase the capabilities of passive imaging surveillance. Camera models and GPS are used to derive a registered point cloud from multiple night-vision images. These point clouds are used to generate 3-D scene models and extract real-world positions of mission critical objects. Analysis shows accuracies rivaling laser scanning even in near-total darkness. The technique has been tested on stereoscopic 3-D video collections as well. Because this technique does not rely on active laser emissions it is more portable, less complex, less costly, and less detectable than laser scanning. This study investigates close-range photogrammetry under night-vision lighting conditions using practical use-case examples of terrain modeling, covert facility surveillance, and stand-off facial recognition.

Engineering deformation monitoring requires techniques which can produce high precision and accuracy, reliable measurements at good temporal resolution and fast processing speed. Moreover, monitoring in civil engineering is generally considered to be labour-intensive and financially expensive, and it can take significant effort to arrange the necessary human resources, transportation and equipment maintenance. Such requirements are especially true for monitoring non-rigid membrane structures (defined in this paper as covers or enclosures in which a fabric surface is pre-shaped and pre-tensioned to provide a shape that is stable under environmental loads). Low cost, automated, photogrammetric techniques therefore have the potential to become routinely viable for the structural monitoring of non-rigid membrane structures in the future. This research is investigating the use of close range photogrammetry to be applied at all stages of membrane structure engineering, from materials testing, through dimensional control in construction to in-situ, as-built monitoring of the finished construct.

Land-based ice cliffs are intriguing features at the margins of glaciers around the world but little is known about mechanisms of their formation and maintenance. The focus of article is on the persistent, rarely-calving ice cliffs on the Kibo glacier, the main peak of Kilimanjaro. Oct 2009 photos were taken covering the sample cliff. PhotoModeler Scanner’s automatic stereo matching lead to a reference digital surface model.

Ablative heat shields have been used to protect hypersonic vehicles during atmospheric re-entry during the Apollo missions and could be used for future flight vehicles as well. However, it is exceptionally difficult to perform reliable tests at conditions which are representative of flight to validate the models. In this study, the AFIT Mach 3 pressure-vacuum wind tunnel was used in combination with models consisting of dry ice. Measurement was obtained with projected laser dots, high-speed multi-camera photography and PhotoModeler PMV (pre-cursor to PhotoModeler Motion).

The vibration response of a model airplane is animated as the result of real-world experimental study of modes. The structural data is captured in 3D by PhotoModeler.

Photo modeling technology has progressed to the point where a dimensionally accurate 3D model can be economically constructed from a series of digital photographs of a structure. We show in this article how a photo model of a structure can be used to create an FEA model from which the modes of the structure can be calculated. The FEA mode shapes obtained from the photo models are then compared with the experimentally derived mode shapes of each structure to demonstrate the validity of this approach to FEA modeling.

Slope failures and landslides associated with earthquakes and typhoons are major natural hazards on Taiwan’s mountain highways. This paper attempts to apply photogrammetry techniques to carry out a speedy in-situ survey. We first create the three-dimensional (3D) model of a brick wall and validate that the average error is 0.28 mm in the measured distance. Afterward, the same measurement procedures are applied to an in-situ mudstone slope. The average error in the estimated distance is 0.41cm. Therefore, the investigating result guarantees the accuracy of applying Photogrammetry to investigate the geometry of in-situ failed slope. (the local copy is the first page).

The finite-element-analysis FEA of bell vibrations required an accurate 3D model of the bell under study. This modeling was done with PhotoModeler Pro and targets.

Another method to collect field measurements for equipment in the field, and a direct way to generate new 3D CAD models, is to take some pictures. Shan Pehlman, design engineer with CDI Corp., says he derives accurate measurements from ordinary photographs through desktop software called PhotoModeler, developed by Eos Systems Inc. When consulting with oil refineries on replacing an aging pipeline, as-built drawings of the old infrastructure may not be available for his reference.

“I chose PhotoModeler Pro from Eos Systems Inc., of Vancouver, Canada. It proved to be easy to use and well documented. The program has worked very well from day one, and I have been very pleased with its accuracy, reliability and user friendliness.”