Interactive vectorization involves the manual creation of features assisted by the ability to snap to raster cells and utilization of the raster tracing and shape recognition tools. Interactive vectorization is typically employed when you want total control of the vectorization process or needs to vectorize a small area of the raster image. It can also be used in situations where the resolution of the scanned image is poor or you have many themes represented in the image and therefore require careful digitizing to ensure that the appropriate raster cells are traced and integrated into the vector-based feature layer.
Interactive vectorization allows a higher level of flexibility since you can use the ArcScan trace tools or the Create Features window construction tools and Editor toolbar sketch construction methods to generate features.
Raster snapping options
ArcScan uses the editing classic snapping environment for raster snapping but also supports its own snapping options that are specific to raster tracing. These can be found on the Raster Snapping Options dialog box, which is accessible from the ArcScan toolbar. These options include settings for the foreground and background colors, maximum raster line width, solid diameter range, and hole size. Maximum raster line width is an important setting for vectorization. Since ArcScan recognizes lines that are less than or equal to the maximum line width value, raster linear elements that do not meet this criteria cannot be snapped to or traced.
Vectorization settings allow you to influence the structure of the output vector features. These settings apply to both interactive and automatic vectorization processes. In raster tracing, vectorization settings affect features that are created using the Vectorization Trace tool. These settings do not influence features that are created using the Create Features window construction tools.
Vectorization settings allow you to fine-tune the outcome of the raster-to-vector conversion. You can use them to control which raster cells are available for vectorization, the degree of generalization and smoothing used to create vector features, and to deal with atypical characteristics of the raster.
Using the vectorization tools
The vectorization trace tools are designed as the main component of the raster tracing task. They allow you to capture raster information by tracing along the foreground raster cells in a semiautomated fashion. The ArcScan toolbar provides two tracing tools: the Vectorization Trace tool and the Vectorization Trace Between Points tool. Both tools work with the existing editing, snapping, and vectorization environments. You should first set the active feature template and any snapping, including raster snapping, options you want to use.
The Shape Recognition tool allows you to click a raster and ArcScan determines the best vector shape (rectangle, square, circle, or ellipse) to create based on the morphology of the underlying raster feature.