Do remote sensing images and DEMs mean the same thing?

If it is archived data, check with the satellite company first, and whether the required time and range have been photographed (not all areas have data). You can find a ** company to inquire for free, and you can also provide post-processing. On the premise that there is data, according to the different satellites, order according to the scene or area.

If it is data within three months, or future data, it needs to be programmed, and it also needs to be ordered through ** company, and the general cycle is 90 days. Beijing Shengshi Huayao Technology Co., Ltd. specializes in remote sensing space information services and was established in 2015. Based on aerospace remote sensing images and geographic information data services, the company has more than 10 years of experience, with a good sales and technical team, since its inception, it has provided high-quality spatial information solutions for various industries, and has won unanimous praise from customers

Not the same thing. Remote sensing imagery.

The concept covers the original images obtained by satellites, and DEM is a product obtained after post-processing of remote sensing images, and not all remote sensing images can be processed to obtain DEM

No. ** is a kind of remote sensing imagery.

Remote sensing imagery is a photograph of the earth. There is no concept of ups and downs.

DEM is a digital elevation model.

Digital Elevation Modal, which refers to the undulation of the ground.

In GIS, a raster data structure is used for storage.

DEM is a band. Remote sensing imagery can be one or more bands.

No, dem is elevation data.

TM image is a remote sensing image taken by Landsat-5 satellite, each point on the image is recorded as the radiation brightness value of the ground, SRTM is a kind of DEM, DEM is a digital elevation model, and each point records the altitude of the ground. I haven't heard of DM images.

With the combination and continuous development of surveying and mapping technology and computer technology. Modern digital maps are mainly composed of DOM (digital orthophoto map), DEM (digital elevation model), DRG (digital raster map), DLG (digital line map) and composite mode. Collectively referred to as 4D.

DOM (Digital Orthophoto Image) Image data generated by using aerial photographs and remote sensing images, corrected by pixels, and cropped according to the frame range. It is rich and intuitive, with good readability and measurability, from which physical geography and socio-economic information can be directly extracted. DEM (Digital Elevation Model) A digital elevation model is a collection of numbers that express the undulating form of the ground in terms of elevation.

It can make perspective drawings and cross-sectional drawings, carry out engineering earthwork calculations, and surface coverage area statistics, which can be used for geomorphological analysis, visibility condition analysis, and flood inundation area analysis related to elevation. DRG (Digital Raster Map) A digital raster map is a digital product in the form of a raster of paper topographic maps. It can be used as a background to correlate with other spatial information for data collection, evaluation and updating, and integrate with DOM and DEM to derive new visual information.

DLG (Digital Line Map) A vector dataset that is hierarchically stored with underlying geographic features on an existing topographic map. The digital line drawing includes both spatial information and attribute information, which can be used in various aspects such as construction planning, resource management, investment environment analysis, etc., as well as as the spatial positioning basis of various professional information systems such as population, resources, environment, transportation, and public security.

dem、dom、dlg、drg

Digital elevation model dem

Digital orthophoto DOM

Digital line drawing dlg

Digital raster imagery DRG

DEM and DTM are the same type of data as digital elevation models that say the same thing a lot of the time.

is a DEM data file, a data quality file, and a README is the data description file.

source

Web Links.

One is a data file and the other is a supplementary file.

1.Contour lines: Contour lines are closed curves of points of equal elevation on a topographic map.

A closed curve that connects points on the ground at the same altitude. Projecting vertically onto a standard surface and drawing on the drawing in scale to obtain a contour line. Contour lines can also be seen as the intersection of horizontal planes at different altitudes with the actual ground, so contour lines are closed curves.

The numbers marked on the contour line are the elevation of the contour line.

Digital Elevation Model :((abbreviated as DEM) is a dataset of the plane coordinates (x, y) and elevation (Z) of regular grid points within a certain range, which mainly describes the spatial distribution of regional geomorphology, and is formed by data collection (including sampling and measurement) and then data interpolation by contour lines or similar three-dimensional models. DEM is a virtual representation of the landform, which can derive information such as contour lines and slope maps, and can also be overlaid with DOM or other thematic data for topography-related analysis applications, and it is also the basic data for making DOM.

Contour lines can be visually displayed in paper or electronic layouts such as topographic maps, but DEM can only be an elevation data, which can be used in a three-dimensional system (to reflect the ups and downs of the terrain) or to process the data for map correction.

4.Three-dimensional: I understand that there are two kinds, one is to use DEM or contour line to import the terrain 3D reflected in the 3D system (provided that there must be remote sensing image data in the system), and the other is the 3D of ground objects (houses, three holes, water bodies, etc.), there are simulated false 3D and solid real 3D, false 3D can be made through some 3D simulation software, etc.; True 3D is achieved by pressing the actual building 1:

1 (or corresponding scale) modeling production (related software has 3dmax, etc.).

5.Remote sensing imagery: There are two types:

1.Satellite remote sensing images, images formed by satellites taking images of the ground through space (remote sensing satellites and radar satellites); 2.Aerial remote sensing images are made by aerial photographing of manned aircraft, unmanned aircraft, hot air balloons and other aerial objects, and its accuracy is high.

Summary: DEM, 3D model, remote sensing image data are all indispensable in GIS, and only when they are complete can they fully reflect the whole picture of space 3D. (There is a lot of knowledge in this area, written by personal experience, I hope you can understand it, and I hope it will help you.) ）

Use DEM for 3D display, and upload the remote sensing image to DEM on.

The fineness of the 3D display depends on the accuracy of the DME or contour lines.

Expresses the undulations of the terrain.

The contour line is that all lines have a height value, the line of this value is the altitude of the terrain, and the contour line is a plane figure, that is, the drawings can be printed, and what you see is the drawings that can express the terrain data and are intuitive.

DEM is a digital elevation model, which needs to be interpreted by professional geographic information software, in which the elevation information of each point or surface is understood, but DEM cannot be output as plane information in the form of any drawing, and it is basically impossible to interpret with the naked eye.

Three-dimensional geographic information system software, this is very simple, that is, I said at the beginning, the DEM information that cannot be recognized by the naked eye, superimposed on remote sensing images, you can intuitively observe the terrain you need to see from all angles. Nowadays, 3D is basically a three-dimensional orientation display.

Remote sensing images, which can be said to be the matrix of DEM, are one of the methods to make DEM data sources... If you shoot the same area from different angles, you can use the angle difference of the area to calculate the target height information. This principle is how we now see 3D movies being filmed.

Are there pros and cons between each ... I can't compare this... Contour lines are the oldest carriers of geographic information...

It was a widely used mapping technique before the advent of computers... dem。。Three-dimensional...

Remote sensing imagery, which now requires the support of a computer, can be used. The latter three are not aimed at the same direction. DEM and remote sensing images are biased towards the direction of mapping.

Give it points... If you don't understand, ask again... 4058845.

At least two images (or with different track coverage areas) can be matched by images, and the tie junction can be found, that is, the image of the same name can be formed.

It must be a stereoscopic image pair.

The SRTM has 1 and 3, 1 is about 30 meters and is free on USGS (open to the world on September 24, 2014), 3 is about 90 meters, USGS, geospatial data cloud, etc. are all free.

Some ** may not be easy to land on the mainland, remember to think of some ways, I won't disclose the specific methods.

Higher resolution requires money to buy, just look for **.

Of course, you can also use stereoscopic image pairs and insar methods to extract them yourself, and the images generally need to be purchased with money.

You can do supervised classification first, and then import the DEM data and classified remote sensing images into ArcGIS for analysis.

This is very difficult, there is no obvious feature point on the dem, you can only roughly register it (find the flow, the ridge or something as a control point), and the accuracy will be very poor. ,