LAB #8 TIN conversion to 3D RHINO GISC, UNIVERSITY OF CALIFORNIA BERKELEY

Transcription

1 LAB #8 TIN conversion to 3D RHINO GISC, UNIVERSITY OF CALIFORNIA BERKELEY The purpose of this laboratory is to process a TIN, Generate a Point Cluster, add a Z to the Point Cluster, Convert to a CAD system, Integrate into RHINO software, Generate a TIN, and export to a CAD file structure. A Practice Data Set: The Claremont Canyon Region DataSet

2 8.1 Process a TIN in ArcMap, 8.2 Generate a point set (shapefile), 8.3 Drape the point set ontop of the TIN and assign Z in ArcScene, 8.4 Convert the point set (shapefile) to CAD in ArcTools, 8.5 Import into RHINO4, 8.6 Generating a TIN in RHINO, 8.7 Saving in RHINO3 (converting to CAD format) 8.8 Assignment: A TIN Model to facilitate Housing Suitability Note: Some of the graphics in this module are from ESRI s ArcGIS Resource Center

3 8.1 Process a TIN in ArcMap I use a set of 5 meter contours here and use the variables in the Spot_ft field.

4 8.2 Generate a point set (shapefile) From ArcToolbox invoke the TIN Node tool to convert your TIN surface to a set of nodes or points with x,y,z values.

5 This generates a set of points from each of the original contour lines.

6 This set of points is a 3D shapefile, confirmed by looking in the data table or viewing it in ArcScene. Note: the TIN can have many points (such as those from a LiDAR dataset) that can overwhelm your computer s ability to process and deal with them in a CAD system. To reduce the number of sample points for a surface, you can generate a regular lattice of points over a surface to be used as your point cloud within a CAD system. There is a cool extension for ArcGIS written by Jeff Jenness to generate a Triangulated Regular Lattice of points.

7 You can download this extension from his site: It is under the Vector-Based Analytic Tools and is called Repeating Shapes, v

8 Note: Once installed you will likely have to reboot your computer to get the extension to work. Here I have loaded the Repeating Shapes icon to my Standard Menu toolbar. Make sure that the layer ClipBoundary is loaded to your Table of Content in ArcGIS. Select the layer ClipBoundary as the bounding hull to generate points within.

9 Click on the icon to launch the extension. Select the first option... Click.

10 With ClipBoundary (1 records selected) Click. Select a triangular pattern as it will produce a better surface in CAD. Click. Select the spacing between points. I select 200 feet here but you will need to experiment with your site to determine how many points will best work for you. I also make the Degrees Offset equal to 45. Click.

11 Click. A triangular pattern of points is produced over the site.

12 8.3 Drape the point set ontop of the TIN and assign Z in ArcScene You can convert 2D features to 3D features by deriving the height value from a surface. The ArcToolbox 3D Analyst Tools Functional Surface Interpolate Shape tool allows you to obtain 3D properties from a surface. Here I convert my 2D Triangulated Regular Point set Points to 3D using the Input Surface tin5m and produce a 3D point Cloud tin5m_interpolatepointcloud.shp.

13 Load the 3D point set (or point cloud) into ArcScene. You can easily see the sampling set of points is much fewer than the original set of points from the contours. 200 feet between points in the point cloud. 100 feet between points in the point cloud.

14 50 feet between points in the point cloud. 8.4 Convert the point set (shapefile) to CAD in ArcTools In ArcToolbox launch the Export to CAD wizard.

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16 8.5 Import into AutoCAD, Save as a DXF, Import into RHINO Launch AutoCAD We know this but it is just a warning so just continue. Continue opening DWG file

17 It usually opens in Top view. Remember it is just a point cloud. When I open a.dwg that was created in another software, the first thing I do is save it as a native AutoCAD.DWG so all the elements function correctly.

18 Since this point cloud was built as a 3D cloud in ArcGIS, it is a 3D cloud in AutoCAD. Look at it from one of the Isometric views.

19 Save this file as a.dxf (an AutoCAD Data exchange Format which is a common format for passing data between some different software).

20 Import into RHINO Launch Rhino Rhinoceros (Rhino) is a NURBS-based 3-D modeling tool (by Robert McNeel & Associates). That is used for design, architecture, landscape architecture, CAD / CAM, rapid prototyping and multimedia. It has a very different data structure than a regular CAD system like AutoCAD, thus data must be imported via a standard interface file format. NURBS-based 3-D modeling tool (Non-Uniform Rational Basis Spline) is a mathematical model used for generating curves and surfaces with precision for handling both analytic (surfaces defined by mathematical formulae) and modeled shapes. Rhino can create, edit, analyze, document, render, animate, and translate NURBS curves, surfaces, and solids with no limits on complexity, degree, or size. Rhino also supports polygon meshes and point clouds. Open the.dxf file you saved in AutoCAD.

21 As with AutoCAD I always save an incoming file to the native Rhino file format, a 3dm file.

22 8.6 Generating a TIN. or a Delaunay triangulation (DT) in RHINO I download and install the Pointset reconstruction tools for Rhino4. The download includes the plugin, a toolbar that maps to all commands. It downlaods as a zipped file When we unzip this file we see two different files, the one ending in.rhp is a Rhino Plug-in file and the one ending in.tb is a toolbar. To install PointSetReconstruction: Close Rhino if it is running. Copy the new PointSetReconstructionTools.rhp into the C:\Program Files\Rhinoceros 4.0\Plug-ins folder From the Menu go to the Tools Options Plug-ins

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24 Select Install.. and then the PointSetReconstructionTools.rhp Plugin file. Select Make sure you check the Point Set Tools Load box

25 Select.

26 Load the new toolbar for PointSetReconstruction. From the Menu go to the Tools Toolbar Layout Select File New

27 Search for the PSetRecon.tb (toolbar) that you downloaded. I put mine in the Plugin folder along with the actual Plugin. Select.

28 Highlight the new Toolbar collection files: PSetRecon Select Toolbar Import Check the PSet Recon tools box

29 The toolbar should appear somewhere on the screen you can dock it anywhere on the Rhino window. The tool we are interested in is the first one. Launch the tool and it asks you to select the point cloud (vertices for building the Delaunay Triangulation (DT) - from our lecture on TIN we know it is equal to the DT). Select the Points in the top view

30 Click Enter and the DT or TIN surface is created. Zoom on the TIN surface to see it is now a surface.

31 Render it....it is a smooth surface

32 Ideally the original set of points would give the best rendering of the surface... but there are likely too many points to work in CAD. It depends on the memory of your computer. Mine could not handle the original point set so I made the regular sample. You can experiment with the different surface displays in RHINO. The key to Rhino is it can make a very effective landscape surface rendering with fewer sample points than a regular TIN in ArcGIS. However, remember this is a rendering and a smoothing of the real world. It looks good but does not exactly or correctly represent the original sample points and their interpolated relationship. However, for design purposes it is effective. Save It as a.3dm file

33 8.7 Saving in RHINO3 (converting to CAD format) You can also export it in AutoCAD format. select surface File Export Selected I export my surface as PointSurfaceDT.DWG

34 I accept the Default format (you can save it as earlier versions of AutoCAD). I can then open it up in AutoCAD and render it as a surface. Remember it was not created in AutoCAD so you will get this warning.

35 This is how it looks in AutoCAD Top View I can render it and it looks as it looked in Rhino

36 8.8 Assignment: A TIN Model to facilitate your Sherman Island Design. Q1: Create a new set of Contours for your Sherman Island Design Site using the Lidar files online at the GISC-RESIN site using tools in "Spatial Analyst Tools" or 3D Analyst Tools. (2 marks) Q2: Create a TIN from the Contours you create in Q1 and display the faces in a single color symbol. (2 marks) Q3: Create and drape a regular set of triangulated points onto your TIN surface. Move the point cloud to Rhino to create a DT surface and then back to AutoCAD. Display the surfaces in both Rhino and AutoCAD. (5 marks) Q4: Post your results as a.pdf file to bspace. Include in your document the simple geo-processing necessary to each of the graphics you submit.. (1 mark for overall clarity and communication) Work with your Sherman Island Group to complete this lab assignment: Here I included a few campus buildings and extruded them onto the surface this is where you are headed in 3D modeling.