IMPORTANT NOTE ON OBJECTS IN ACAD
(1) Whether the polyline is open or closed: Open polygons and curves always create surfaces but closed polylines and curves can create either.
(2) Which tab is active at the top of the ACAD workspace (See Figure 1) – If the Solid tab is active, a solid is created; if the Surface tab is active, a surface object is created; if the Home tab is active, by default, a solid is created from closed polylines (this default can be changed once a command is active by entering ‘M’ for Mode at the prompt) – Solids seem to translate into the COE format and import into Cyclone much better than surfaces, which sometimes will not show up in Cyclone at all in the COE format.
SET UP THE ACAD MODEL SPACE
1. Configure/Open the Cyclone MS and set up the ACAD model space (See the GMV’s “Leica CloudWorx 4.2 and AutoCAD 2012 – Digitizing a Point Cloud in 2D” for more information)
2. Create Layers for each of the 3 slices and the final column object, making the bottom slice’s layer active
3. Adjust the object geometry association variable in CAD -> command line: DELOBJ > adjust to value zero
(NOTE: This number determines whether the original geometry used to create a 3D object – in this case polylines – are retained or deleted when the object is created. This value can range from ‘0’ through ‘-3′, with ‘0’ retaining all geometry and with ‘-3′ deleting all defining geometry. Retaining geometry is recommended for analysis and any possible back-tracking. Search “DELOBJ” in ACAD help for more information)
SETUP ACAD MODEL SPACE – CONT.
In the first example, the column is sliced 3 times on the y-axis. Tracing the slices creates 3 polylines representing the section cuts from the bottom, middle, and top sections of the columns -> These cross sections will then be lofted to one another, forming the modeled column object.
USE THE CLOUDWORX SLICE TOOLBAR
1. Clip Point to Slice -> uses two parallel planes to define the slice; only those points between the two planes are shown > Command line: CWSLICE or Cloudworx > Clip Point Cloud > Slice > Define Axis > LC in viewport to place 1st and 2nd clipping planes. NOTE: Current Slice can be moved one step (equal to width of the slice) forward (CWSLICEF) or backward (CWSLICEB) along its axis
CLIP POINTS TO SECTION
2. Clip Points to Section > uses single plane with only those points on one side of the plane visible > Command line: CWSECTION or Cloudworx > Clip Point Cloud> Section View > LC in viewport to define axis and direction (positive or negative)
TRACE AND SNAP TO POINT CLOUD
3. Trace first section cut, snapping directly to point cloud > Top View > Make correct layer current > Zoom in to view points comfortably and refresh point cloud to confirm all points visible (do this periodically, especially when zooming in/out) >Command Line: PL or POLYLINE to trace the profile/outline of the bottom slice of the column
REMEMBER: (1) Enable OSNAP “NODE” to snap to points (2) At command line: type “U” during active polyline command to undo vertices/go back without ending the command (3) At command line: PEDIT allows polyline(s) to be edited, joined, etc. (4) See ACAD Help: Drawing and Editing Polylines for more information
3A. Repeat Steps to create the polylines for the remaining section cuts (note you may create more or less slices as desired – a higher number of slices and/or increased complexity results in a more accurate tracing but also requires a higher and more difficult set of calculations to loft/join the separate sections; when too complex, the lofting command may fail to calculate the final object as desired) > Confirm each section is made of only one polyline (use PEDIT -> JOIN and PEDIT -> CLOSE to join and close multiple polylines)
3D MODELING MAIN TOOLBAR
RETURN TO ORIGINAL COORDINATES AND EXPORT
TIPS FOR LOFTING
EXAMPLES OF LOFTING
You are reading the series: Modeling an Irregular Feature from Point Cloud Data - 3D
- Modeling an Irregular Feature from Point Cloud Data – Method 1
- Modeling an Irregular Features – Method 2
- Modeling an Irregular Features – Comparing Modeled Objects to Original Points