Basic concepts of GIS

Factor Model (Feature)
element is the core term in Geotools, which is the description of geospatial data on
The basic unit of the image, which describes an objective geographical entity in the real world, such as: A River, a bridge
Can be understood as a factor.

Raster data
Raster data is a picture of the Earth taken from the top down, using discrete units to store its value, each pixel of the picture has a specified value
The server itself is stored, the transmission speed is fast, the server pressure is small, many for png,jpg,gif
Large amount of data, slow to update

Vector data
Vector data is just a storage node, such as arrows, lines, dots, and so on. The contour of the object is stored, and the raster data is appropriate for the content of the object being expressed.
Vector data types somewhat, lines and polygons.
Small quantity, fast data update
Server pressure, high technical requirements

Projection
The process of drawing a spherical earth to a plane is called a projection.
World Geodetic System of 1984 WGS-84
A system of geocentric coordinates adopted internationally. The origin of the coordinate is the center of mass of the Earth, and the z-axis of the rectangular coordinate system of the geocentric Space points to BiH (International time)
1984.O-Defined Protocol Earth Pole (CTP) direction, x-axis points to the intersection of the 0 Meridian plane of BiH 1984.0 and the CTP equator, and the y axis and the z axis, the x axis vertically constitute the right-hand coordinate system,
Called the 1984 World Geodetic coordinate system.

Spatial database
Building a OGC Web service
The Open Geographic Information System Association (open GIS CONSORTIUM,OGC), the OGC specification, is dedicated to providing unity of data and service interoperability between geographic information systems.

Spatial Analysis

(1) Spatial query and spatial measurement
Query based on spatial relation
Query based on spatial relation and attribute feature
Address matching Query
Geometric measurement: The length of the line, including the size of the surface.
Shape measurement
Measurement of centroid
Distance measurement

(2) Buffer analysis

Proximity: The degree of similarity between two objects in a geographical space is described.
Buffer: An area of influence or service scope for geo-spatial objectives.
Buffer analysis: Given a spatial object or set, determine their neighborhood, the size of the neighborhood is determined by the radius r of the neighboring region.

(3) Superposition analysis

Superposition analysis: The related subject layer is composed of the data level, superimposed to produce a new data level operations, the results of the original two-tier or multi-layer elements have attributes.
Divided into the following five categories
Visual Information Overlay
Dot and Polygon Overlay
Line and Polygon Overlay
Polygon Overlay
Grid Layer Overlay

(4) Network analysis
Network data structure: The main chain (link) and node.
Main network analysis function
Path analysis
Dijkstra algorithm for calculating shortest path
Resource allocation

(5) Space interpolation
Spatial interpolation: Used to convert measured data from discrete points to continuous data surfaces.