Quais são os tipos mais comuns de sistemas de coordenadas personalizados em SIG e como eles são usados?

As in any case when it comes to spatial analysis, it depends. It depends on the scale, what you're going to represent and how you're going to represent it. Above all, why and for whom. However, for much of the work carried out at a professional technical level, the use of Universal Transverse Mercator (UTM) will be more convenient, given how easy it is to communicate the information to technicians in other areas of knowledge.

Projected coordinate systems flatten the earth, which is a globe (geoid). The most common is Web Mercator, which is a spherical model that simplifies the calculations and sacrifices some accuracy to do it. Google Maps where you can zoom out and see all the world as a "rectangle" is an example of Web Mercator. As places are shown nearer to the North and South Pole they are stretched, distorting their size. For example, greenland is NOT the same size as Africa! In fact, Africa is about 14 times bigger!

In GIS, custom coordinate systems are created to accommodate specific geographic regions, mapping projects: -UTM (Universal Transverse Mercator) Zones: UTM zones divide the world into 6-degree longitudinal strips, each with its own coordinate system. - Local Coordinate Systems: Local coordinate systems are custom coordinate systems created for a specific area, project, or survey. - Projected Coordinate Systems: Projected coordinate systems are used to transform geographic coordinates (latitude and longitude) onto a flat surface (e.g., a map). These custom coordinate systems are used in GIS to represent geographic features, perform spatial analysis, and create maps for various applications .

Common types of custom coordinate systems in GIS include local, engineering, projected, State Plane, local datum, vertical, custom Transverse Mercator, remote sensing-specific systems, regional or national grids, local grids, custom datum transformations, and 3D coordinate systems. These systems are tailored to specific mapping needs, providing accurate representation for diverse applications such as city planning, engineering projects, state-level mapping, remote sensing, and 3D modeling. Custom coordinate systems are crucial for minimizing distortions and ensuring accurate spatial data analysis in GIS.

This will be different according to the country, so you should see what the standard of the projection that implemented in the country for example Hungary used HD72 (Hungarian Datum), for others it might use WGS84. You could also fit to the project reference in one of maps that you have by overseeing their data source.

Geographic coordinates point to a location on the globe (not a flat map). The earth "Geoid" is not a perfect circle or sphere. It is lumpy and even "sea level" can deviate. This does not work well in the math used to create positions so an approximation is calculated creating a spherical surface to represent locations on the surface as coordinates. These usually Latitude, Longitude and height, which can be shown in multiple ways like Degrees Minutes Seconds or Decimal Degrees where Minutes and Seconds are shown together as a fraction of Degrees. The most common Geographic Coordinate System is World Geodetic System 1984.

Local Coordinate Systems are used frequently in CAD for construction, where a site property has (perhaps) a 0,0 coordinate someplace and everything else in the CAD drawing relative to that. The units are something more construction friendly, like Meters or Feet, depending on the unit used in your country.

Creating custom coordinate systems is something you should avoid without serious consideration. Usually the coordinate system can be found from an authority who maintains it. An example is the Canadian Spatial Reference System (CSRS) for NAD83 and WGS84, which differ slightly versus the American definitions of the same. Using the American references usually built into software like QGIS or ArcGIS Pro will shift data slightly. This can be fixed by downloading the Coordinate Transformation parameters and using these in your software. For example, defining or transforming your data into NAD83(CSRS). If needing a custom coordinate system, consult with the data creator or a survey expert to do this properly.

When considering custom coordinate systems in GIS, several additional factors should be taken into account to ensure accurate spatial analysis and interpretation: 1. Datum: The choice of datum affects the alignment of coordinates with the Earth's surface. Different datums may result in shifts in coordinates, so it's essential to use the appropriate datum for your region or project to minimize errors. 2. Units of Measurement: Consistency in units (e.g., meters, feet) is crucial for accurate analysis and interpretation of spatial data. Ensure that all data layers and coordinate systems use the same units to avoid conversion errors.

Ia ora na, bonjour, Hello, I live in french polynesia, country which is as wide as the européen union. There is the RGPF system, which is a local geogeaphic coordonate system based on the UTM. Problem, when you want to represent data in the one layer for all of the country... To do that, the only way, is to pass in WGS 84, to group data and represent all in the same way ... This an exemple of local system limite. Thank you for your feedback ...