ArcScan provides tools that allow you to convert scanned images into vector-based feature layers. The process of converting raster data to vector features is known as vectorization. Vectorization can be performed manually by interactively tracing raster cells or automatically using the automatic mode.
The main enhancement for ArcScan is the integration with the new editing experience using feature templates, which are introduced in ArcGIS 10. Feature templates define all the information required to create a feature: the layer where a feature will be stored, the attributes a feature is created with, and the default tool used to create that feature. When performing interactive vectorization with ArcScan, you first need to choose a feature template on the Create Features window. With automatic vectorization, you choose a feature template directly on dialog boxes such as Generate Features.
While ArcGIS 10 introduces new tools for snapping through the functionality on the Snapping toolbar, ArcScan uses the classic editing snapping environment rather than the settings on the Snapping toolbar. To perform raster snapping with ArcScan, you must enable classic snapping on the Editing Options dialog box. Classic snapping resembles the snapping experience that was available while editing in previous releases.
When you enable classic snapping, editing tools only use the classic snapping environment. However, georeferencing tools, the Measure tool, and other non-editing tools continue to use the snap settings on the Snapping toolbar. Therefore, once you have completed your work with ArcScan, you should disable classic snapping so the editing tools can take advantage of the Snapping toolbar.