Digital Sources

There are a number of sources that should be investigated to obtain digital informa­tion on a site that can be used for creating the base map and base sheet. Similarly, most surveyors retain their property surveys in a digital format that can be purchased as a CAD file or hardcopy. This typically requires some trial and error to make sure the written dimensions of the property lines match the scaled distances of the enlargement. The amount and detail of on-site measuring that is required depends on what previous site data has been obtained. If the information is obtained online, it will likely have to be printed at the size of the screen image and then enlarged via a copy machine to a common graphic scale such as 1" = 10′. Although this technique lacks the precision of a survey, it is nevertheless a viable substitute if no survey exists. Figure 6-15
Example of GIS site information. If the digital information is obtained as a CAD file or GIS database on a CD, then it can be easily printed at a desired scale. In this situation, on­site measurements might be necessary to locate the doors and windows of the house, paved areas, fences/walls, utilities, plant materials, and so on. Much of this data can be easily accessed online and sometimes can be purchased on a CD and then downloaded directly onto an office computer. The most detailed scale typically shows the configuration and length of property lines along with the location of the house and other structures on the site (Figure 6—15). On-Site Measuring
Taking and recording measurements directly on the site is the last and most detailed source of dimensional information. Some local governmental offices, such as the auditor’s office, tax agency, zoning office, and plan­ning department, have property records including maps in a digital format.