October 20, 2015

Posted on October 20, 2015 by Synergis Application Consultant, Bill Knittle
Model-based field layout is a common trend in the industry today. In an earlier post, Revit was used to align coordinates from a survey to the Revit Site model. This process utilized the shared coordinate system of Revit to then push that shared coordinate to the Building model or models. By establishing control on the site and building, all trades can install their components by referencing common control points.

Control Points

Setting up control on the Building model is the next step in any building layout process once site coordinates and control for the site are established. A quick method for adding control points is to use the structural grids. The Control Points command on the Set up panel of the APL ribbon tab starts the process. Once the command is selected, the user will be offered a variety of ways in which to add Control Points in their model.
When the process begins, the first step in the process is to give the Control Points a numbering scheme, description, and role.
Next, the user will have to choose the method in which to add the Control Points. The Place on Grids command will automatically locate a point element at each grid intersection. The user will be prompted for the elevation of the points. Finally, the user will window select all grids in the view. The option to finish the process is located on the Options Bar.
The XYZ command will require manual coordinate-based input of the point elements.
The Place Point or Place Points will allow the user to manually place Control Points on the grid intersections. When using Place Point or Place Points, the user can select an Element surface or use the current Workplane to define the elevation of the Control Points.
When the Building Control Points dialog appears, the user simply selects the Done button. The Control Points will be added to all the structural grid intersections. They are a Generic Model family and quite small. It may be necessary to modify the family in order to read them better in the view. The family is located in C:\Program Files (x86)\Autodesk\Autodesk Point Layout <year>.

Annotating Control Points

Annotating the Control Points is just as easy. APL provides an Add Tag command. APL offers a variety of different tag options from the Tag Style dialog. Spot Elevation and Spot Coordinate will report the coordinates of each point and measure it to the centroid of the Point elements. Do not use the base Revit Spot and Coordinate dimension commands as they will measure to faces of the Point element.
By default, the Tag will not display the Description. However, they can be turned on after placement via editing the Tag’s Type Properties. Again, the wizard will allow the user to choose the method in which tags are added. The All button will add tags to all the Point elements in the view. The Types button will list the Types in the Point element Family to select from. The Filter button will bring up a Filter dialog that allowing the user to filter the selection based the Point element’s number or description. Lastly, the user can just fence in an area on the plan.
In any case, the user will be prompted to choose whether to add a leader to each tag placed in the view. When it’s all done and said. The tags are placed and, they can be moved if necessary.
The Control Points for the Building can now be exported for use in the field. APL has the ability to export the points added to the model as well as, background image to underlay with the points.
On the APL tab, the user would select Export. In the Export Points to File dialog the user specifies their export preferences. The Point Order is crucial and must match the order of the coordinates in the shared coordinate system of the model. The Output Units can be in either Decimal Feet or Meters. General Options allow the user to decide whether a DXF plan is generated, duplicate points are identified, the point elevations are set to 100 feet, and the Code column is included. All the points can be selected or just some. The extension of the file can be a delimited and output as a CSV, TXT, or DAT file.  As mentioned above, the coordinate system should match the coordinate system used in the model. A Filter is provided to isolate points by number and description. A name field is provided for the exported files as well as, a location where the file will be written.
When exporting the background DWG or DXF, it important to setup a view and its visibility graphics so that it can be selected during the exporting process.
After the preferences are set, the user simply selects the OK button and the export process is executed. The files that are created can be emailed to the field and imported directly into the data collector. The exported data can be viewed in AutoCAD and Excel to verify for correctness.