Photogrammetrische Messmethoden
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| License | CC Attribution 4.0 International: You are free to use, adapt and copy, distribute and transmit the work or content in adapted or unchanged form for any legal purpose as long as the work is attributed to the author in the manner specified by the author or licensor. | |
| Identifiers | 10.5446/14869 (DOI) | |
| IWF Signature | C 13225 | |
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| Production Year | 2008 |
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| IWF Technical Data | Video-Clip ; F, 5 min |
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00:00
BauxitbergbauMachineVolumetric flow rateOpticsModel buildingDisc brake
00:37
Disc brake
00:48
Volumetric flow rateWater vapor
00:58
Model buildingVolumetric flow rateModel buildingWater vaporPlane (tool)Reference workStream bedTracing paperRailroad
02:10
Water vapor
02:25
AmpouleVolumetric flow rateWater vaporFahrgeschwindigkeit
02:50
PortalkranModel buildingAircraft engineering
03:02
Reference work
03:27
CaliberComputer animation
03:42
Angle of attack
03:48
Reference workComputer animation
03:54
Model buildingPattern (sewing)Lecture/Conference
04:17
FaltenbildungSatelliteStream bedModel buildingTypesettingComputer animation
04:55
SeeschiffComputer animationDiagram
05:44
Reamer
Transcript: English(auto-generated)
00:03
The Federal Waterways Engineering and Research Institute in Karlsruhe, the BAW, conducts research in its laboratories using large physical models. Optical measuring methods are applied to yield high quality and high quantity data. Great precision is essential.
00:28
In the model of the Obernau-Wir near Aschaffenburg, the flow behavior of the river mine is being examined at various water levels. A machine specially designed in the BAW dispenses white polypropylene discs
00:42
at programmable frequency and controllable quantities. These traces, as they're called, precisely follow the flow on the water surface. They're carried along by the current and make it clearly visible. A fixed camera records their course.
01:02
From the data gathered, a computer then evaluates the flow behavior. The technique is known as two-dimensional particle tracking velocimetry, PTV for short, which records surface speed on camera. The four light points marked are the precisely calculated reference points.
01:26
For a one-camera measuring system, all the points must be at the same level, floating on the surface of the water. This solid bed half model of the river Elbe near Schoenberg is to measure currents in the groin fields.
01:43
Reference points again provide orientation and correlation. All the points are different. They each have their own circular barcode. For the three-camera system used here, the points don't have to be in the same measuring plane. The traces make the flow behavior in a groin field visible,
02:02
shown here in time-lapse. The groins here have cut-out sections, which are designed to change flow behavior. The traces are filmed by three cameras
02:21
and can therefore be evaluated three-dimensionally. The water level, the position of the traces, and their speed in the flow can be ascertained at one and the same time. The computer evaluation can then depict the flow behavior in the groin field.
02:42
Here we see the velocities and here the water levels. This measuring gantry above a model of the river Oder can be maneuvered to any point in the model.
03:03
Before it's used on the model, the three-dimensional measuring system has to be spatially calibrated. The reference points are fixed at different heights for this. The configuration of the three cameras to one another on the rigid frame is measured.
03:23
This has to remain constant during the whole measuring procedure. Here, too, the features and orientation of all the components in the system, such as sensors and lenses, must be precisely determined before every measurement. With the calibration completed, measuring can begin.
03:44
The three cameras take pictures of the surface from different angles. The reference points enable the measured data to be collated. From above, a grid pattern is projected down onto the surface of the model.
04:02
The spatial position of every point on the grid can now be ascertained via triangulation. An expanded version of this system also ascertains the mean water level in the measuring field at the same time. The optical paths of the video cameras are calculated.
04:23
Then the underwater changes on the riverbed can also be measured during the test. This three-dimensional terrain model consists of a total of 4,000 individual data sets taken every 10 seconds over a period of 11 hours.
04:42
The different colors show the different levels of the riverbed. Red represents higher areas, green deeper levels. Using numerical models, computed on the basis of the data gained from the physical model, the course of a ship traveling upstream can be simulated. The ship seeks the best course for avoiding shallows.
05:04
A number of variants are examined. The dynamic simulation process, also developed by the BAW, takes account of the physical characteristics of the ship.