altitude

Model), referred to as DEM. It is represented as an ordered array of numbers.

The solid ground model of surface elevation is a digital terrain model (digital

zone

Model (DTM).

Branches. It is generally believed that DTM describes various geomorphic factors including altitude, such as slope, slope direction, slope change rate and so on.

Linear and nonlinear spatial distribution, in which DEM is a zero-order simple single digital landform model and others are like slopes.

On the basis of DEM, the geomorphic characteristics such as slope, slope direction and slope change rate can be deduced. The other two branches of DTM are various non-landforms.

A numerical model that represents features in matrix form, including natural and geographical elements related to the ground, as well as socio-economic and human elements.

Elements, such as soil type, land use type, rock depth, land price, commercial advantage area and so on. Actually DTM is the number of grids.

According to one of the models. The main difference between it and the grid representation of an image is that the image represents the genus of the whole pixel with one point.

In DTM, the points in the grid only represent the attributes of points, and the attributes between points can be obtained by interpolation.

There are many ways to establish DEM. In terms of data sources and collection methods, there are: (1) direct measurement from the ground, such as GPS and total station.

Field measurement, etc. ; According to aerial or space images, it is obtained by photogrammetry, such as stereoscopic coordinate observation and aerial three-dimensional encryption.

Method, analytical mapping, digital photogrammetry, etc.; (3) Collect from existing topographic maps, such as grid reading method and digitizer walking method.

Tracking and scanner semi-automatic acquisition, and then generate DEM through interpolation. There are many methods of DEM interpolation, mainly block interpolation.

Partial interpolation and single point moving surface interpolation. At present, the commonly used algorithm is to construct an irregular triangle through contour lines and elevation points.

Network (triangle

anomalistic

Network,

Tin for short). Then DEM is established by linear and bilinear interpolation based on TIN.

Because DEM describes the ground elevation information, it is widely used in surveying and mapping, hydrology, meteorology, geomorphology, geology, soil, engineering construction,

Communication, meteorology, military and other national economy and national defense construction, as well as humanities and natural sciences have a wide range of applications. If you are working,

In engineering construction, it can be used for earthwork calculation and visibility analysis. In flood control and disaster reduction, DEM is used for hydrological analysis, such as catchment.

Water area analysis, water network analysis, rainfall analysis, flood storage calculation, inundation analysis, etc.

In wireless communication, available

Cell phone base station analysis and so on.