GIS Notes

What is GIS?

GIS stands for Geographic Information Systems, which are tools and techniques for capturing, managing, storing, processing, and analysing spatial data. It is part of the broader geospatial technology ecosystem, which also includes drones, remote sensing, and GPS.

Geospatial data (Raw)

Definition: Any data that includes a geographic component, describing the location and attributes of features on Earth, contains raw information, like points, lines, and polygons, that has a real-world location associated with it.

Examples: a car's GPS location or a customer's address.

GIS data (Organised)

Definition: Geospatial data that is structured, stored, and analysed using Geographic Information System software.

Examples include a digital map of roads created from GPS data or layers of data showing flood-risk areas.

Summary: Geospatial data is the foundation: the raw material for all things spatial. GIS is a toolset that may include tools like ArcGIS from Esri.

Other:

In the AEC space, building and Asset management rely heavily on GIS within BIM.

ArcGIS is the industry leader in GIS tooling, and comes in three versions: 

• Desktop (ArcPro, Arc Toolbox, ArcCatelog),
• Server (), 
• SaaS ArcGIS Online (AGOL).

 GIS data comes in various formats such as Shapefiles, GeoJSON, KML, or geodatabase feature layers.

What WGS84 and GeoJSON Mean?  

These are the most common formats for storing position (WGS84) and shape data with coordinates (GeoJSON) 

WGS84 (World Geodetic System 1984) is the global standard geographic coordinate reference system. It represents positions on Earth using latitude and longitude in decimal degrees.

GeoJSON is a widely used format for encoding geographic data structures in JSON. According to RFC 7946, all GeoJSON coordinates must use WGS84 (EPSG:4326).

The OSGB/OSGB36 coordinate system, also known as the Ordnance Survey National Grid or British National Grid (BNG), is a geographic grid reference used in Great Britain.  

The European Terrestrial Reference System 1989 (ETRS89).

Standards and formats Notes

ISO 19115: International standard for geographic information metadata.

Shapefiles: Upload as a ZIP archive containing .shp, .shx, and .prj files.

File Geodatabases: Must be compressed into a ZIP file before uploading.

WMS/WMTS Services: Add Web Map Service (WMS) or Web Map Tile Service (WMTS) layers by providing the service URL.

Prefix Conventions

• Points: Use prefix pt_
• Polygons: Use prefix py_
• Lines: Use prefix ln_
• Raster: Use prefix rs_

ESRI Competitors

Esri have ArcGIS, which is the gold standard in GIS. It's pretty expensive if you don't need the feature set offered by AGOL/Esri.  
Google offers easy-to-set-up and use mapping, geo services and APIs Google Maps Platform Pricing   . I'd usually choose this when hardcore analytics are not needed

Common source of data used to mash onto maps

DEFRA,
Environmental Agency, 

Natural England,

Esri Living Atlas,

Open Geospatial Consortium  NB!