What is secondary capture in the context of GIS?

In the context of Geographic Information Systems (GIS), secondary capture refers specifically to the process of converting analog data into digital format, which often involves techniques like scanning hard copies or manually digitizing existing maps and documents. This process is essential for creating digital datasets that can be analyzed and manipulated within GIS software.

When hard copy maps or documents are scanned, they are transformed into raster images that can later be georeferenced, allowing them to be used alongside other spatial data in a GIS. Manual digitizing may involve tracing features from a hard copy map to create vector data layers. This transformation process is critical for integrating historical or non-digital information into modern GIS systems for analysis and decision-making.

In contrast, direct surveying of land involves real-time data collection in the field, where measurements are taken using various surveying instruments. Field data collection refers to the acquisition of data from the environment using GPS or other technologies, while immediate real-time monitoring pertains to capturing live data continuously as events unfold. None of these processes involve converting existing non-digital information into a digital format, which is the essence of secondary capture.