How to Compare Two DWG Revisions (DWGCOMPARE) & Export Revision Cloud Reports
Visually diff architectural, structural, and MEP drawing revisions in GstarCAD 2027 using DWGCOMPARE, color-coded additions/deletions, and automated REVCLOUD extraction.
⚡ Quick Executive Fix
Run DWGCOMPARE (View > Compare > DWG Compare), select the baseline Revision A and updated Revision B .dwg files, and use the comparison toolbar to step through colour-coded differences (Green = New, Red = Deleted, Grey = Unchanged) and export Snapshot Revision Clouds.
1. Engineering Root-Cause Diagnosis inside the AC1032 DWG Database
When an external architect or client issues a revised `.dwg` background without markup clouds, manually hunting for moved columns, deleted door openings, or changed pipe diameters across 25,000 entities is virtually impossible. GstarCAD 2027's native **`DWGCOMPARE` (`COMPARE`)** engine performs a cryptographic and geometric entity-level diff across both geometry and text attributes in under 2 seconds.
2. Step-by-Step Resolution Protocol in AutoCAD & GstarCAD 2027
1. Launch DWGCOMPARE & Assign Baseline vs. Revised Files
Go to Collaborate / View → DWG Compare (or type DWGCOMPARE). Select your baseline (`Rev_01.dwg`) and revised (`Rev_02.dwg`) files. GstarCAD renders a live overlay where **Green** highlights newly added entities, **Red** shows deleted/previous positions, and **Grey** dims unchanged background geometry.
2. Filter Text, Hatch & Block Attribute Differences
In the DWG Compare settings gear, toggle **Compare Text** and **Compare Block Attributes** so even a subtle change in a steel beam schedule callout (`IPE 300` → `IPE 360`) is flagged inside a revision cloud.
3. Export Comparison Snapshot or Import Changes
Click Export Snapshot to generate a dedicated audit `.dwg` complete with polygonal Revision Clouds (`REVCLOUD`) around every geometric delta, ready for PDF plotting or RFI submission.
3. Automated AutoLISP Diagnostic & Repair Script (C:AUTOREVCLOUD)
Load the following production AutoLISP routine into GstarCAD 2027 or AutoCAD via APPLOAD (or add it to gcaddoc.lsp) to automate this repair across affected project files:
(defun C:AUTOREVCLOUD ( / ss i ent minPt maxPt p1 p2 p3 p4)
(vl-load-com)
(princ "\nSelect modified entities to enclose in an automated Revision Cloud: ")
(if (setq ss (ssget))
(repeat (setq i (sslength ss))
(setq ent (vlax-ename->vla-object (ssname ss (setq i (1- i)))))
(vla-GetBoundingBox ent 'minPt 'maxPt)
(setq minPt (mapcar '- (vlax-safearray->list minPt) '(150.0 150.0 0.0))
maxPt (mapcar '+ (vlax-safearray->list maxPt) '(150.0 150.0 0.0)))
(command "_.RECTANG" "_non" minPt "_non" maxPt)
(command "_.REVCLOUD" "_Arc" 100.0 100.0 "_Object" (entlast) "_No")
)
)
(princ "\n[AUTOREVCLOUD] Generated bounding revision clouds around selected deltas.")
(princ)
)4. Diagnostic System Variables & Edge-Case Matrix
| Failure Symptom / Scenario | Command / SysVar | Production Remediation Rule |
|---|---|---|
| Consultant sent new DWG without change notes | DWGCOMPARE |
Highlights additions (Green), deletions (Red), and unchanged (Grey). |
| Small text value change inside title/beam tag | Enable 'Compare Text' |
Diffs string contents of TEXT, MTEXT, and Block Attributes. |
| Revision cloud arcs look huge or microscopic | REVCLOUD > Arc Length |
Set Min/Max Arc Length to ~3x your plotted text height (e.g. 8mm * scale). |
Experience Faster, Corruption-Free DWG Engineering in GstarCAD 2027
Built by Suzhou Gstarsoft Co., Ltd. (SSE: 688657), GstarCAD 2027 features multi-threaded DWG open/save, built-in RegApp/Scale-List scrubbers, and perpetual licensing.