Automatic (batch) vectorization can involve a series of procedures to achieve an acceptable raster-to-vector conversion. It can be as simple as executing one command to generate the vector features. Depending on the state of the input raster data you are working with, the vectorization process varies. This section is intended to provide an overview of the automatic vectorization experience.
Preprocessing the raster
Raster preprocessing is the practice of preparing your raster data for vectorization. This involves removing noise and raster elements that should not be vectorized. It also involves adding new features or filling holes and gaps to improve the input data, which will ultimately help the vectorization succeed. ArcScan supports tools to perform these types of operations. These tools can be found in the Raster Cleanup menu and the Raster Painting toolbar. Techniques such as painting, erasing cells, and exporting to a new raster file are available.
Defining the scope
The ability to narrow the scope of the vectorization can help save you time and allow you to be more productive. ArcScan facilitates this process with raster selection tools, which allow you to focus on the data that is targeted for conversion via interactive selections and expression-based queries. You can select a series of connected cells with your pointer or use the Select Connected Cells dialog box to perform a more intelligent selection based on criteria that you specify. You can select cells in either the foreground or background and use a selection as the basis for feature generation. You can also use these tools to assist with the raster cleanup process.
Determining optimal settings
Once you have prepared your raster data for vectorization, the next step is to determine the best settings for the raster-to-vector conversion. Using the right vectorization settings for your data is crucial for ensuring an accurate and successful vectorization. There is no other process in ArcScan that has greater influence on output vector feature construction. With vectorization settings, you control how intersections are treated and how many vertices are used to construct a line feature. In addition, you control how much smoothing should be applied to the lines as well as whether to close gaps. Once you have found the optional vectorization settings, you can save them with the map document or export them to an ArcScan style, which can then be reused for similar data.
Generating vector features
The final step in the automatic vectorization process is the generation of vector features.
ArcScan supports centerline and outline vectorization methods in automatic mode. The centerline vectorization method allows you to generate vector line features at the center of the raster cells. This method is the most common type of vectorization. The centerline vectorization method is the default setting. The outline vectorization method allows you to generate vector polygon features at the borders of the raster cells.
Typically, automatic vectorization is performed for the entire raster layer, and therefore, it is the default technique. ArcScan also supports tools that allow you to vectorize a user-defined portion of the raster. This provides flexibility in cases where you only need to convert a certain area of the raster. You can also take advantage of the cell selection tools and use them in concert with the Generate Features command to vectorize only the currently selected raster cells. ArcScan supports vector data creation for two layer formats: shapefiles and geodatabase feature classes.