In Singapore CAD Standard,
“SS CP 83: Part 5” aims for visual checking by using colours. That aspect of
visual checking is perhaps most important for submissions to authorities where
certain colours have been specified for “proposed”, “existing” and “deleted”
elements.
In BIM, Revit phase filtering process for A&A
took a lot of time since that phases are applied to elements and controlled by
views. For instance, in a residential project with several types of unit, after you did 3
colours changing in a typical unit group, it cannot update the rest of the
similar groups in the Revit files. To gain the productivity by saving man hours,
keeping smaller native file size (especially Revit) and avoiding creation of
extra building objects (elements), alternatively we can use Autodesk Design
Review to compare the original sheet to the revised sheet to identify
differences in the geometry of building objects or elements by colors in
accordance with SS CP83 Part 5 for projects previously done and approved with
BIM submission and to re-submit the changes as amendment BIM submission.
Design
Review can be used to compare differences in vector content (geometry) between
two 2D sheets in separate DWF files that have the same sheet size and unit
settings.
I
am going to show you how to compare design changes with Design Review. First of
all, open your approved DWF in Design Review, and select a sheet that you want
to compare.
(Above figure shows a DWF Approved Floor Plan sheet:
Elements in Cyan colors can be re-exported from Revit by overriding Phases Filters.)
Go to Tools menu, and then from Canvas
tab, click Compare Sheets. The compare dialog box will open.
From the compare dialog box, click
Options. The Compare Options dialog box will open.
Now you can change the default colors
to the required Magenta and Yellow in accordance with SS CP83 Part 5. Click OK
to go back to the compare dialog box.
From the compare dialog box, click Browse.
Navigate to the folder to find the updated DWF file of the same drawing set,
created at a different time and then select the sheet you wish to compare to
the sheet currently in the canvas.
Final result is essentially an
automatic markup of the DWF sheet showing what are the proposed elements(NEW) in
Magenta and what have been deleted(DEMOLISHED) in Yellow.
Any
changes between the 2D sheets are identified as separate markups, one for
Additions and one for Deletions, in the open DWF file. The Additions markup identifies
the geometry that would need to be added to the original sheet to make it match
the second sheet. The Deletions markup identifies the geometry that would need
to be deleted from the original sheet to make it match the second sheet.
Most of the time, contractor will
receive a new version of a DWF file, but changes were not identified by the
architect. The contractor can use Design Review to compare the original sheet
to the revised sheet to identify differences in the geometry, including changes
in polyline attributes such as line pattern or line weight.
Doing this electronically with a process that
identifies additions and deletions goes beyond what we traditionally done by
aligning and eyeballing sheets of paper or overlapping two CAD drawings and
finding changes.
Occasionally, comparing DWF files
may produce some unexpected results. Since DWF is a published file format, DWF
files are susceptible to the output eccentricities of publishing programs.
Be aware that Design Review will
identify all geometric differences between two DWF files, whether the
difference is made intentionally by a designer or unintentionally by an anomaly
in a publishing program.
I
hope this process will improve over time with future releases of Autodesk
Design Review.
