2. Briefly describe the main steps of spatial analysis?

Briefly describe the main steps of spatial analysis:

First, vector space analysis.

Vector space analysis mainly mines the potential information of space targets through the joint analysis of spatial data and spatial model, and the basic information of these space targets is nothing more than their spatial position, distribution, shape, distance, orientation and topological relationship, in which the spatial relationship of space targets consists of distance, orientation and topological relationship.

It is a spatial feature between geographical entities and can be used as the basis of data organization, query, analysis and reasoning. By dividing geospatial targets into different types, such as points, lines and areas, the morphological structures of these different types of targets can be obtained. Combining the spatial data and attribute data of space objects, it can be used for spatial calculation and analysis of many specific tasks.

1, entity merger

The combination of primitives is vector space aggregation, which combines or converts data types according to spatial adjacency and classification attribute fields to realize the merger of spatial regions (data integration). As a result of spatial aggregation, more complex categories are often transformed into simpler categories, and this analysis and processing method is often needed in the comprehensive transformation of mapping from place and region to large region.

2. Spatial query

Spatial query is to distinguish the spatial topology between the elements of the input layer and the query layer or the query range of interactive input (including, separating, intersecting, intersecting with the circumscribed rectangle), and extract the primitives that meet the topological discrimination conditions from the input layer.

3, superposition analysis

Overlay overlay analysis is the operation of overlaying two or more map elements to create a new element layer. In this way, the original elements are divided into new elements, and the new elements combine the attributes of the original two or more layers of map elements. That is to say, overlay analysis not only generates a new spatial relationship, but also links the attributes of the input data layer and generates a new attribute relationship. Superposition analysis is to calculate and analyze the attributes of new elements according to a certain mathematical model, and then produce the results needed by users or answer the questions raised by users.

Second, the grid space analysis

Spatial analysis based on raster data is the basis of GIS spatial analysis, which mainly includes: distance mapping, density mapping, surface analysis, statistical analysis, reclassification, grid calculation, visibility analysis, terrain factor analysis, hydrological analysis and other functions.

1, distance mapping

Distance mapping is to analyze and map according to the distance between each raster and its nearest neighbor (also called "source"), thus reflecting the relationship between each raster and its nearest neighbor. A lot of relevant information can be obtained through distance mapping to guide people to plan and utilize resources reasonably.

2. Density mapping

Density mapping mainly calculates the data distribution of the whole area according to the input values and distribution of known point elements, thus producing a continuous surface. It is mainly generated on the basis of point data, and the ring area is searched with each grid point to be calculated as the center, and then the density value of each grid point is calculated.

3. Surface analysis

Surface analysis mainly generates new data sets, such as isoline, slope, slope direction, mountain shadow and other derived data, and obtains more information reflecting the spatial characteristics and spatial pattern implied in the original data set.