How to difference two CAD File Revisions in TBC

While there is no automated way to do this in TBC, you can follow these steps to provide a quicker way to identify the differences between two CAD files in TBC.

In this image - Lines in Rev 1 Data Only are Red
In this image - Lines that are Rev 2 Data only are White
In this image - all lines that are the same in REV 1 and 2 look Pink / Off Red

You can now more easily see what has changed, what has been added and what has been removed.
The data prep steps to make this work are as follows. I recommend processing each Revision drawing data in separate TBC projects to limit selection times and also make the working data smaller. Then output the result of the cleanup into a VCL file. You can then import the 2 VCL files into a clean project and do the difference analysis.

The steps to prep the data could all be automated to get the final data more quickly, and we could look at a differencing tool to make the auto identification of differences possible, and then maybe relayer the difference data onto user defined layers e.g.

Added in REV 2
Removed In REV 2
Changed in REV 2

Potentially this could be run on linework and or text to find changes

  1. For each CAD File
  2. Open a new project in TBC
  3. Import the CAD File
  4. Delete Plan Sheet Data from Project Explorer
  5. Delete any data that you know you are not looking at - this includes sheet boxes, Titles and Borders, Other Sheet data in Plan View that you are not interested in, Viewport boundaries etc etc.
  6. Select all of the data
  7. Use Advanced Select to select and delete object types that you may not care about e.g. Hatches
  8. Explode all Block References
  9. Repeat the deletion of Hatches that were created from Exploded Blocks
  10. Repeat the Explode of Blocks - repeat steps 9 and 10 until All Blocks are exploded
  11. Change all Linestyles to By Layer
  12. Change all Lineweights to By Layer
  13. Change all Colors to By Layer
  14. Use Advanced Select to select all CAD Lines and convert them to linestrings using the Convert to Linestring command
  15. Create a selection set of the Rev 1 or Rev 2 data
  16. Use RPS Layer Manager to Prefix all layer names with Rev 1 - or Rev 2 - etc.
  17. Use the Assign Name by Layer command to Name all the objects with their source layer name (optional step)
  18. Create a new Layer Group called REV 1 DATA or REV 2 DATA
  19. Use RPS Layer Manager to regroup all of the Rev 1 or Rev 2 layers into the REV 1 DATA or REV 2 DATA groups.
  20. Use TBC Layer Manager to Change the Lineweights of all the REV 1 Layers to 0.5 or 0.6 etc. and if Rev 2 change to 0
  21. Use TBC Layer Manager to change all Layer Linestyles to Solid for REV 1 and REV 2 Data
  22. Use TBC Layer Manager to Change all the colors of REV1 Layers to Red and Rev 2 Layers to White
  23. Use TBC Layer Manager to delete unused empty layers
  24. Use TBC Layer Manager to set all REV 1 Data layers to Background Display Priority
  25. Use TBC Layer Manager to set all REV 2 Data Layers to Foreground Display Priority

Color = Red
Lineweight = 0.5 or higher
Linestyle = Solid

REV 2 Data
Color = White
Lineweight = 0
Linestyle = Solid

Now when you Turn on selected layers from the REV 1 Data Group and the equivalent REV 2 Data layers, you should see the following

Data that is in REV 1 but not in REV 2 will be Red and easily visible
Data that is in REV 2 but not in REV 1 will be White and Easily Visible
Data that is common in Both REV 1 and REV 2 files will look Pink (it is actually a narrow white line on top of a bold Red line but graphically it looks Pink).

You can now review Layer by Layer or groups of layers to identify things that have been Added, Removed or Changed

If you turn on the CAD group in Advanced View Filter Settings, you can turn off Blocks, Text, Mesh and Lines as you see fit as a separate filter control to the Layers and Layer Groups.

Defects found in TBC that are being addressed
In the process of reviewing TBC for this CAD to CAD comparison workflow, the following defects were found and reported - they should be addressed by next release. All have a work around.

  1. CAD Lines do not seem to honor the Display Priority setting in TBC - Change all CAD Lines to Linestrings is a work around
  2. Cannot change the Property Varies for Linestyles to By Layer. You can if you first change the Varies to Solid and then to By Layer
  3. TBC did not like some Hatches in the DWGs that I imported - you can either Relayer them and hide them and then not select them to explode or you can select and delete them if you are not going to difference them.

Hope this helps