Industrial Measurement Articles

“In this interview, we talk to Jean Sans of Experts-Yachts about the uses of photogrammetry in maritime surveys. An early adopter of the technology, Jean has been employing photogrammetry in his practice since 1983.”

Photogrammetry helps reduce the time to create marine enclosures and covers. Costa Marine Canvas specializes in producing high-end, custom marine furniture, soft goods, enclosures, and covers. One of the most difficult of those tasks is creating windscreen enclosures for large and complex fly-bridge structures. A typical flybridge enclosure might have five 5-foot tall panels, ranging in various lengths, and combined to be 20 feet or more. While basic in appearance, each panel consists of 20 or more complex pieces of various materials fastened together by adhesives and sewing to fit and fasten to the bridge structure.

“At full-scale, measuring the spinnaker shape in real sailing conditions (flying shape) is also valuable for sail designers as they would benefit a feedback for their designs. Nonetheless it remains complex to measure spinnaker flying shapes partly because of their inherent instability, like flapping of the luff. This work presents a full-scale experimental investigation of spinnaker flying shapes with simultaneous measurement of the aerodynamic loads on the three sail corners, as well as navigation and wind data. The developed experimental set-up and photogrammetric method to acquire the flying shape of the spinnaker are presented”

“The reverse engineering applications has gained great momentum in industrial production with developments in the fields of computer vision and computer-aided design. The reproduction of an existing product or a spare part, reproduction of an existing surface, elimination of the defect or improvement of the available product are the goals of industrial reverse engineering applications. The first and the most important step in reverse engineering applications is the generation of the three dimensional (3D) metric model of an existing product in computer environment. The possible usage of terrestrial photogrammetry in reverse engineering application is investigated based on low cost photogrammetric system. The main aim was the generation of the dense point cloud and 3D line drawing of the ship model by using terrestrial photogrammetry. Then 3D line drawing operations, point cloud and orthoimage generations have been accomplished by using PhotoModeler software. As a result of the proposed terrestrial photogrammetric steps, 0.5 mm spaced dense point cloud and orthoimage have been generated.”

“Recent years have seen a vast change in measurement technology. Data that were once extremely difficult and possibly dangerous to collect can now be collected and processed using only a digital camera and off-the-shelf software. Currently, digital close-range photogrammetry has made it possible to efficiently model a variety of structures in a budget-friendly manner. In this paper, a range of different types of structures were modeled. The viability of using this type of measurement is studied for different structure types, and the feasibility of using this method in conjunction with or as a replacement of other means is discussed”

Long-term campaigns and flexible structures are regarded as two of the most challenging subjects in monitoring engineering structures. Long-term 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. When dealing with flexible structure monitoring, it is of paramount importance that any monitoring equipment used is able to carry out rapid sampling. Low cost, automated, photogrammetric techniques therefore have the potential to become routinely viable for monitoring non-rigid structures.

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.

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).

What is unique in this study is that accuracy was assessed on a system with four independent cameras and all those cameras were consumer-grade cameras with zoom lenses. This is a configuration one might use for a low-cost PMV system (for tracking object movement and shape change over time).

This paper describes a method for the acquisition of the flying shape of spinnakers in a twisted flow wind tunnel. The method is based on photogrammetry. Results are shown comparing design versus flying shape of the spinnaker and the impact of wind velocity and wind twist on the flying shape.