GIS techniques and technologies

As stated in the previous section, GIS technologies heavily utilize digital information. There are quite a few different digital data formulation methods that are used. The most common method of data formulation, however, is digitization, for obvious reasons. Let’s take a quick step back and define digitization. Digitization is where you have a physical copy of a map or survey data and transfer it into a digital medium by means of CAD or similar programs that have georeferencing capabilities. With the abundance of orthorectified imagery devices such as satellites, aircraft, Helikites, and UAVs, heads-up digitizing is becoming the go-to resource by which geographic data is extricated.

Heads-up digitizing is copying via tracing geographic data directly on top of aerial imagery. Heads-down digitizing is the process of tracing the geographic form onto a separate digitizing tablet, and is the more traditional method.

GIS can reference any variable that can be located spatially and temporally. Areas or degrees in Earth spacetime might be recorded as dates and times of event with the x, y, and z facilitates speaking to longitude, scope, and height. These GIS directions may speak to other information for measured frameworks of temporospatial reference. These GIS coordinates may represent other data for quantified systems of temporospatial reference. Some examples of temporospatial references include film frame number, stream gauge station, highway mile markers, surveyor benchmarks, building addresses, entrance gates, street intersections, water depth sounding, and POS or CAD origin or units.

Temporospatial data recorded units that are applied can vary widely; this includes using the exact same data, and because of this, all Earth-based spatial-temporal location references are relatable to one another. This makes it so that, ultimately, all of these references are able to represent a real physical location or extent in spacetime.

GIS data represents real objects with digital data determining the mix. That data includes objects such as roads, land use, elevation, trees, waterways, highways, and so much more. These real objects are generally divided into two distinct abstractions: discrete objects and continuous fields. Discrete objects are those such as houses, and continuous fields are things such as rainfall amount and evaluations. There are two broad methods that are used to store data in a GIS for both kinds of abstractions mapping references that have become a tradition: raster images and vectors. Points, lines, and polygons are typically used to map location attribute references.

There is a new hybrid method for storing data that is currently being used, which is able to combine three-dimensional points with RGB information at each point. This is able to return a 3D colorized image. GIS thematic maps are becoming much more realistically descriptive in what they are able to show or determine.

There are some very popular GIS file formats that are used by different software applications, such as the following:

• Shapefiles
• Geopackage
• World file
• AutoCAD DXF
• Cartesian coordinate system
• ADRG
• Binary files such as BSQ or BIP
• DRG
• ECRG
• GeoTiff
• JPEG2000
• RAW