3D MODEL GENERATION FOR DEFORMATION ANALYSIS USING LASER SCANNING DATA OF A COOLING TOWER<br />C. Ioannidis(a), A. Valani(...
Introduction<br />The Hellenic Public Power Corporation S.A. required the 3D survey of the external and internal surfaces ...
Equipment<br />HDS2500 (FOV 40ox40o) <br />HDS3000 (FOV 360o horizontal and 270o vertical angle)<br />		spot size = 6mm <b...
The tower in numbers<br />56 m<br />80 diagonals<br />97 m<br />40<br />pedestals<br />83 m<br />
The tower in numbers<br />Sn: Geodetic station <br />Ln: Scanner set up<br />26 stations of the geodetic network that was ...
Registration<br />27 scans to register <br />20 scans for the interior of the tower <br />10 for the lower part <br />10 f...
Registration with no targets<br />Object shape<br />The top of the tower is a horizontal ring<br />Solution approximation<...
Registration<br />Cyclone was used for the registration<br />All of the scans registered in a common reference system<br /...
3D Modeling for Finite Element Analysis<br />Finite Element Analysis (FEA): a computer-based numerical technique for calcu...
Data preparation for 3D modeling<br />Noise removal<br />Creation of different point clouds for the parts of the tower<br ...
3D Modeling of the Cooling-Tower<br />Data: Laser scanner point clouds and 3D faces<br />S/W: Raindrop Geomagic Studio 7<b...
Shape Mode<br />Polygonal mesh <br />creation<br />Assembly of <br />Tower parts<br />Corrections of<br />polygonal mesh<b...
Shape Mode<br />Polygonal mesh <br />creation<br />Assembly of <br />Tower parts<br />Corrections of<br />polygonal mesh<b...
Important corrections<br /><ul><li>Deletion of crossing triangles
Deletion of floating triangles
Hole filling
Spike removal
Relaxing</li></ul>Shape Mode<br />Polygonal mesh <br />creation<br />Assembly of <br />Tower parts<br />Corrections of<br ...
Shape Mode<br />Polygonal mesh <br />creation<br />Assembly of <br />Tower parts<br />Corrections of<br />polygonal mesh<b...
Phase Mode<br />Patch definition<br />and corrections<br />Grid<br />definition<br />NURBS creation<br />and corrections<b...
Phase Mode<br />Patch definition<br />and corrections<br />Grid<br />definition<br />NURBS creation<br />and corrections<b...
Phase Mode<br />Patch definition<br />and corrections<br />Grid<br />definition<br />NURBS creation<br />and corrections<b...
Phase Mode<br />Patch definition<br />and corrections<br />Grid<br />definition<br />NURBS creation<br />and corrections<b...
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3 d model generation for deformation analysis using laser scanning data of a cooling tower

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3 d model generation for deformation analysis using laser scanning data of a cooling tower

  1. 1. 3D MODEL GENERATION FOR DEFORMATION ANALYSIS USING LASER SCANNING DATA OF A COOLING TOWER<br />C. Ioannidis(a), A. Valani(a), A. Georgopoulos(a), E. Tsiligiris(b)<br />(a)Department of Rural and Surveying Engineering, National Technical University of Athens <br />Email: cioannid@survey.ntua.gr<br />(b)Public Power Corporation S.A. <br />Greece <br />
  2. 2. Introduction<br />The Hellenic Public Power Corporation S.A. required the 3D survey of the external and internal surfaces and the production of a 3D solid model of an old cooling tower in order to record its current state, decide for repairs if necessary and investigate the possibility of upgrading it. NTUA was assigned with the task and the details of the survey and the results are presented. <br />
  3. 3. Equipment<br />HDS2500 (FOV 40ox40o) <br />HDS3000 (FOV 360o horizontal and 270o vertical angle)<br /> spot size = 6mm <br /> position accuracy = ±6mm (in 50m range)<br />Reflectorless total station<br />
  4. 4. The tower in numbers<br />56 m<br />80 diagonals<br />97 m<br />40<br />pedestals<br />83 m<br />
  5. 5. The tower in numbers<br />Sn: Geodetic station <br />Ln: Scanner set up<br />26 stations of the geodetic network that was established (3 stations inside the tower)<br />2,900 geodetically acquired check points <br />22,000,000 points acquired by the laser scanners<br />27 scanner set ups<br />6 days of fieldwork<br />
  6. 6. Registration<br />27 scans to register <br />20 scans for the interior of the tower <br />10 for the lower part <br />10 for the upper part<br />7 scans for the exterior of the tower<br />16 targets were measured and used for registering the 10* scans of lower part of the interior<br />20 targets were measured and used for registering the scans of the exterior<br />* 10 scans that cover the upper part of the interior were acquired with no targets<br />
  7. 7. Registration with no targets<br />Object shape<br />The top of the tower is a horizontal ring<br />Solution approximation<br />A plane is fitted on a selection of points that belong on the top horizontal ring and through the coefficients of the equation of the plane the ω and φ rotations that must be applied so that the plane be horizontal are calculated<br />Solution refinement<br />The upper- and lower- part point clouds are compared via difference vectors that are calculated on a grid defined on the overlapping area and the relative ω and φ rotations and relative translation are thus eliminated<br />
  8. 8. Registration<br />Cyclone was used for the registration<br />All of the scans registered in a common reference system<br />For all overlapping scans cloud constraints were created<br />There were no common targets nor overlapping scans between the interior and exterior<br />Interior: 53 constraints (30 cloud constrains)<br /> Mean Absolute Error= 5 mm<br />Exterior: 39 constraints (7 cloud constraints)<br /> Mean Absolute Error= 4 mm<br />
  9. 9. 3D Modeling for Finite Element Analysis<br />Finite Element Analysis (FEA): a computer-based numerical technique for calculating the strength and behavior of engineering structures<br />3D Models for FEA:<br />Ordinary CAD models are usually unsuitable<br />A mesh of a NURBS surface is normally required <br />Required formats: IGES, ACIS, STEP and STL<br />3D Model characteristics:<br />Simplified models<br />“Geared” for FEA<br />
  10. 10. Data preparation for 3D modeling<br />Noise removal<br />Creation of different point clouds for the parts of the tower<br />Creation of 3D faces for parts that were impossible to scan (e.g. pedestals, inside part of the shell extending from the lintel up until the doorstep)<br />
  11. 11. 3D Modeling of the Cooling-Tower<br />Data: Laser scanner point clouds and 3D faces<br />S/W: Raindrop Geomagic Studio 7<br />SHAPE MODE<br />PHASE MODE<br />Boundary<br />definition<br />Exporting<br />to IGES<br />Corrections of<br />polygonal mesh<br />NURBS creation<br />and corrections<br />Assembly of <br />Tower parts<br />Grid<br />definition<br />Polygonal mesh <br />creation<br />Patch definition<br />and corrections<br />
  12. 12. Shape Mode<br />Polygonal mesh <br />creation<br />Assembly of <br />Tower parts<br />Corrections of<br />polygonal mesh<br />Boundary<br />definition<br />
  13. 13. Shape Mode<br />Polygonal mesh <br />creation<br />Assembly of <br />Tower parts<br />Corrections of<br />polygonal mesh<br />Boundary<br />definition<br />
  14. 14. Important corrections<br /><ul><li>Deletion of crossing triangles
  15. 15. Deletion of floating triangles
  16. 16. Hole filling
  17. 17. Spike removal
  18. 18. Relaxing</li></ul>Shape Mode<br />Polygonal mesh <br />creation<br />Assembly of <br />Tower parts<br />Corrections of<br />polygonal mesh<br />Boundary<br />definition<br />
  19. 19. Shape Mode<br />Polygonal mesh <br />creation<br />Assembly of <br />Tower parts<br />Corrections of<br />polygonal mesh<br />Boundary<br />definition<br />
  20. 20. Phase Mode<br />Patch definition<br />and corrections<br />Grid<br />definition<br />NURBS creation<br />and corrections<br />Exporting<br />to IGES<br />
  21. 21. Phase Mode<br />Patch definition<br />and corrections<br />Grid<br />definition<br />NURBS creation<br />and corrections<br />Exporting<br />to IGES<br />
  22. 22. Phase Mode<br />Patch definition<br />and corrections<br />Grid<br />definition<br />NURBS creation<br />and corrections<br />Exporting<br />to IGES<br />
  23. 23. Phase Mode<br />Patch definition<br />and corrections<br />Grid<br />definition<br />NURBS creation<br />and corrections<br />Exporting<br />to IGES<br />
  24. 24. Accuracy evaluation<br />GEODETIC DATA<br />1250 geodetically acquired points on the external surface of the tower<br />Only 146 points deviate more than ± 3 cm from the polygonal surface model (μ =-1 cm, σ =±1.5 cm)<br />
  25. 25. Accuracy evaluation<br />MATHEMATICAL SURFACE<br />A one-sheeted hyperboloid was fitted on the data and using the equation 18.000 simulation points were calculated<br />There are areas where deviations of ±20 cm are observed but the greatest part fits the mathematical model quite well (μ =-2.4 cm, σ =±4cm)<br />
  26. 26. Conclusions<br />The use of a commercial laser scanner (±6mm at 50m) and the processing of the acquired data with Cyclone (registrations) and Geomagic (3D model generation) leads to results of adequate accuracy and satisfying quality for applications such as this<br />
  27. 27. Thank you for your attention<br />

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