Today we are releasing a major update to OpenDrawing's text recognition engine. The new model delivers significantly improved accuracy on handwritten annotations and legacy typed schematics and reduces manual correction time by 80% on archives that previously required the most review effort.
What Changed
The previous OCR model was strong on clean, typed annotations from modern CAD-exported drawings but degraded significantly on two common legacy drawing types: drawings with hand-lettered callouts (prevalent in drawings from the 1960s through 1980s) and drawings produced on older typewriters or dot-matrix plotters with inconsistent character spacing and resolution.
The new model was trained on a significantly expanded dataset of legacy engineering drawings spanning five decades of drafting styles, including hand-lettered relay schematics, typewritten equipment schedules, and rubber-stamp annotations common in utility and industrial archives. The result is consistent accuracy across drawing eras, not just on recently-drafted PDFs.
What This Means in Practice
For customers with legacy paper archives, the practical impact is fewer items in the manual review queue. A drawing package that previously produced 40 low-confidence text annotations requiring human confirmation now produces 8–10. Review time per drawing drops from 25–30 minutes to under 10 minutes for most legacy drawing types.
The improvement is most pronounced on three annotation types that historically drove the most review volume: device number tags (e.g., "87T-1A"), handwritten equipment specifications (transformer kVA ratings, cable sizes), and rubber-stamped or typed title block data. These now process reliably without manual correction in the large majority of cases.
Who This Affects
All existing customers automatically have access to the updated model - no configuration changes are required. New drawings submitted from today will be processed with the new engine. For customers who want to reprocess previously-digitized drawings to take advantage of the improved accuracy, the OpenDrawing team can arrange batch reprocessing on request.
If you are evaluating OpenDrawing for a legacy drawing archive with substantial hand-lettered or typewritten content, send us a sample of your drawings and we will show you what we can extract.