Below are some of the most common terms you will encounter when using ArcScan.
Automatic (batch) vectorization
Automatic vectorization is defined as an automated technique for converting raster data into vector features. This process relies on user input to control how to perform the vectorization. Factors such as image resolution, amount of noise in the image, and the actual content of the scanned document all play a role in determining the outcome of the vectorization.
ArcScan supports two vectorization methods: centerline and outline. Centerline vectorization will generate vector features along the center of the raster linear elements. Outline vectorization will generate vector features at the border of the raster linear elements.
Interactive vectorization (raster tracing)
Raster tracing is useful in cases in which you need to have more control over the vectorization process or need to vectorize a small portion of an image. This process is known as interactive vectorization and is similar to the existing techniques used to create features while editing. Interactive vectorization consists of several components: raster snapping, raster tracing, and shape recognition.
The ArcScan extension supports the ability to snap to raster cells. Although not required for raster tracing, raster snapping can help ensure that you create features accurately. You can snap to raster centerlines, intersections, corners, ends, and solids.
Raster cleanup and painting
The success of a vectorization may be determined by the state of the scanned document at the time of the conversion. It is sometimes necessary to modify the image prior to the generation of features. This process, referred to as raster preprocessing, can help you clean up certain portions of the raster that will help define the scope of the vectorization. The Raster Cleanup tools provide the means to perform these steps. In addition, raster selections can be used in combination with or independently of raster cleanup to isolate the raster cells you want to vectorize.
Raster cell selection
ArcScan supports the ability to select raster cells. Connected raster cells are raster pixels that share contiguous borders. This can be in a side-by-side or diagonal arrangement. This functionality allows you to select portions of the raster for various reasons, such as vectorization, export, or removal.