Definition of GIS underlying development

Today, I heard a friend talk about the definition of the underlying GIS development in the group. I thought it was quite fun and I turned around.

1. Combined with the second-and third-dimensional Secondary Development of specific industries, based on the mainstream GIS platform (secondary development, not the underlying development)
2. rendering 3D images of specific industry models on the extension interface of the existing 3D GIS platform. This development method belongs to the semi-bottom layer and directly calls the DirectX 3D or OpenGL library;
3. Using existing open-source GIS libraries, such as common gdal libraries, and directly developing GIS application products in combination with your own industry, this is also an underlying development method;
4. underlying development of the 3D GIS platform. This development method is generally based on DirectX 3D (developed on the Windows platform), OpenGL graphics library, or the Ogre engine (these two can be used for cross-platform development ). This development method is already very underlying.
5. relying only on the underlying API development provided by windows or other operating systems, rather than other libraries, is a thorough GIS underlying development.