The way software interprets a drawing depends partly on the information available in the source file.

For scanned drawings and raster PDFs, AI typically combines optical character recognition (OCR) with computer vision to identify dimensions, symbols, notes, and drawing regions. Vector PDFs preserve geometric entities and text that may be easier to extract separately. Native CAD files can provide additional information about geometry, features, and product manufacturing information (PMI).

The challenge is associating that information correctly. Recognizing a position tolerance is one task; identifying the features it controls and interpreting the associated datum references is another.

Drawing-review tools also need access to relevant engineering requirements. A callout may conform to ASME Y14.5 while conflicting with a company's manufacturing guidelines. Some tools combine drawing interpretation with standards, checklists, and previous engineering decisions to identify those discrepancies.

These technical differences become especially relevant when comparing automated drawing checkers.