Editing Geographic information system (section)

====Primary data capture====
[[Surveying|Survey]] data can be directly entered into a GIS from digital data collection systems on survey instruments using a technique called [[coordinate geometry]] (COGO). Positions from a global navigation satellite system ([[Satellite navigation|GNSS]]) like the [[Global Positioning System]] can also be collected and then imported into a GIS. A current trend{{As of?|date=September 2024}} in data collection gives users the ability to utilize [[Rugged computer|field computers]] with the ability to edit live data using wireless connections or disconnected editing sessions.<ref>{{cite journal|last1=Marwick|first1=Ben|last2=Hiscock|first2=Peter|last3=Sullivan|first3=Marjorie|last4=Hughes|first4=Philip|title=Landform boundary effects on Holocene forager landscape use in arid South Australia|journal=Journal of Archaeological Science: Reports|volume=19|pages=864–874|date=July 2017|doi=10.1016/j.jasrep.2017.07.004|s2cid=134572456}}</ref> The current trend{{As of?|date=September 2024}} is to utilize applications available on smartphones and [[Personal digital assistant|PDAs]] in the form of mobile GIS.<ref>{{citation |last1=Buławka |first1=Nazarij |last2=Chyla |first2=Julia Maria |chapter=Mobile GIS in Archaeology – Current Possibilities, Future Needs. Position Paper |chapter-url=https://publikationen.uni-tuebingen.de/xmlui/handle/10900/101847 |title=CAA: Digital Archaeologies, Material Worlds (Past and Present) |year=2020 |publisher=Tübingen University Press |location=Tübingen |isbn=978-3-947-25115-5 |s2cid=246410784}}</ref> This has been enhanced by the availability of low-cost mapping-grade GPS units with decimeter accuracy in real time. This eliminates the need to post process, import, and update the data in the office after fieldwork has been collected. This includes the ability to incorporate positions collected using a [[laser rangefinder]]. New technologies also allow users to create maps as well as analysis directly in the field, making projects more efficient and mapping more accurate.

[[Remote sensing|Remotely sensed]] data also plays an important role in data collection and consist of sensors attached to a platform. Sensors include cameras, digital scanners and [[lidar]], while platforms usually consist of aircraft and [[satellite]]s. In England in the mid-1990s, hybrid kite/balloons called [[Allsopp Helikite|helikites]] first pioneered the use of compact airborne digital cameras as airborne geo-information systems. Aircraft measurement software, accurate to 0.4&nbsp;mm, was used to link the photographs and measure the ground. Helikites are inexpensive and gather more accurate data than aircraft. Helikites can be used over roads, railways and towns where [[unmanned aerial vehicle]]s (UAVs) are banned.

Recently, aerial data collection has become more accessible with [[miniature UAV]]s and drones. For example, the [[Aeryon Scout]] was used to map a 50-acre&nbsp;area with a [[ground sample distance]] of {{convert|1|in|cm|2}} in only 12&nbsp;minutes.<ref>{{cite web |url=http://www.aeryon.com/news/pressreleases/248-softwareversion5.html |title=Aeryon Announces Version 5 of the Aeryon Scout System &#124; Aeryon Labs Inc |publisher=Aeryon.com |date=6 July 2011 |access-date=13 May 2012 |archive-date=10 June 2020 |archive-url=https://web.archive.org/web/20200610142031/http://www.aeryon.com/news/pressreleases/248-softwareversion5.html |url-status=dead }}</ref>

The majority of digital data currently comes from [[photo interpretation]] of aerial photographs. Soft-copy workstations are used to digitize features directly from [[Stereoscopy|stereo pairs]] of digital photographs. These systems allow data to be captured in two and three dimensions, with elevations measured directly from a stereo pair using principles of [[photogrammetry]]. Analog aerial photos must be scanned before being entered into a soft-copy system, for high-quality digital cameras this step is skipped.

Satellite [[remote sensing]] provides another important source of spatial data. Here satellites use different sensor packages to passively measure the reflectance from parts of the [[electromagnetic spectrum]] or radio waves that were sent out from an active sensor such as radar. Remote sensing collects raster data that can be further processed using different bands to identify objects and classes of interest, such as land cover.