The scale of the topographic map used in urban planning is consistent with the scale of the planning drawing. That is to say, the scale of the urban planning map is based on the scale of the topographic map of surveying and mapping. Therefore, for the overall urban planning, the scale of surveying and mapping should be 1:10000-1:25000 for large cities, and 1:5000 for small and medium-sized cities. -1:10000 scale topographic map. The scale of topographic maps used in detailed urban planning is 1:1000-1:2000, sometimes 1:500.
DEM is widely used in the field of urban planning and design. Using the spatial analysis function of ArcGIS, you can extract surface features from DEM data, such as contour extraction, slope extraction, and aspect extraction. The extracted slope features can be used to analyze the soil erosion sensitivity of the planned area and the suitability of urban construction; the extracted contour and slope distribution information can be used as the basis for planning road selection; the extracted slope information, It can be used as a reference for the layout of urban construction land and the construction of artificial forests and grasses.
Digital elevation model (DEM) is one of the most widely used geographic information data, and it is the data foundation for three-dimensional spatial processing and terrain analysis. The data accuracy requirements of each industry are different. Many industries use the open and free DEM with a resolution of 90 meters and 30 meters. Industrial applications such as urban planning, transportation route planning, geological disaster prevention and control, and urban cadastral monitoring put forward higher requirements on the accuracy of DEM data, requiring data with higher resolution, higher accuracy, and faster update cycles. At present, there is no sub-meter level of DEM that can do large-scale DEM. The accuracy of DEM data extracted through stereo pairs can reach 1-2 meters, and the cost is relatively high.
In order to better meet the needs of users using data, after a large amount of data comparison, LSV has now launched the 5-meter resolution digital elevation model DEM and digital surface model DSM!
The data is collected by Interferometric Synthetic Aperture Radar (IFSAR), and processed by advanced stereo technology to precisely edit and process the water area and sea level, etc., to obtain a 5-meter resolution digital surface model (DSM) and a 5-meter resolution digital terrain model ( DEM). Because IFSAR is not affected by clouds and weather, it can provide seamless cloud-free data products.
Advantages
1. Wide coverage
The coverage area is wide, covering an area of 15 trillion km2, covering more than 40 countries and regions around the world.
2. High data accuracy
The vertical accuracy is 1m RMSE (1.65m LE90), the details are more abundant, and the artificially constructed canal can be seen on the DEM.
3. Complete data classification
This data set contains digital surface model (DSM) and digital terrain model (DEM). DSM can reflect the ground ups and downs to the greatest extent. It can be used to monitor the growth of trees in mountainous areas and can be used to monitor urban development in urban areas. Detection.
4. The water area is well treated
This data set provides accurate coastlines, flat water surfaces, detailed water channels, etc.
5. Cloudless data
IFSAR can penetrate clouds, smoke and haze and provide clear cloud-free data.
6. Wide range of applications
It is widely used in surveying and mapping, agriculture, forestry, hydrology, geology, natural disasters, guidance and positioning, ship inspection and other fields.
Data parameter
Covering more than 40 countries
Sensor IFSAR
Spatial resolution 5m
Vertical accuracy 1.6m (LE90)
Horizontal accuracy 3.5m (CE90)
Effect comparison
DEM and DSM comparison
The data set provides DSM and DEM two results to facilitate the application in different fields. DSM is a digital surface model, which can see the city's building outlines, roads and other artificial ground surfaces, and can measure the height of buildings. DEM is a digital terrain model, which completely removes man-made buildings, roads, etc.
Comparison of the effect of building height measurement
In addition to accurately measuring the height of a building, it can even measure the distance between building units.
Comparison of three kinds of DEM in the same urban area
Only the approximate topography around the city can be seen in the SRTM3 data
The terrain surrounding the city can be seen in the ALOS data
Various details such as buildings, roads, and water networks can be seen in the 5-meter DEM data
Three kinds of DEM contour generation comparison
In SRTM3, the surrounding terrain can only be roughly judged without details; in the ALOS data, only finer terrain can be seen; in the 5-meter DEM data, in addition to the rich terrain details, you can also see the fine architectural contours and road contours of the city information.
Three kinds of DEM 3D terrain comparison
5m DEM, you can see the platform with a drop of about 8m
In the ALOS-12m data, the platform has disappeared, but you can see that the terrain in the area is basically undulating
In the SRTM3-90m data, the platform and nearby terrain has almost disappeared
