What are the methods of topographic mapping?

Topographic mapping methods: analog mapping and digital mapping. At present, digital mapping method is mainly used in topographic mapping.

Surveying and mapping method of engineering topographic map

(1) total station digital mapping

Total station digital mapping is the main method of engineering large-scale topographic mapping, and there are two main types of digital mapping systems based on total station:

1, divided into digital recording modes (total station+electronic notebook or manually recorded data are then transmitted to the mapping system for processing to generate digital maps, and mapping is carried out in the office);

2, electronic tablet mode (total station+portable computer or PDA personal data assistant, field mapping), to achieve "what you see is what you measure, what you see is what you get".

Digital mapping system not only has the functions of basic data editing, graphic layering and symbol configuration, but also has the functions of inputting and hooking attribute data, constructing irregular triangulation from discrete points to generate contour lines, influencing data integration and superposition, and converting different data formats.

(2) GPS RTK digital mapping technology, this method is completely similar to the total station, using RTK system instead of or in combination with the total station.

(3) Digital photogrammetry and remote sensing mapping: For large-scale topographic maps and large-scale engineering construction site mapping, aerial photos, remote sensing images, airborne lidar scanning systems or light aircraft can be used for image capture. Using digital photogrammetry or remote sensing image processing system to make DOM (digital orthophoto map), DEM (digital elevation model), DRG (digital raster map), and? DLG (digital line drawing map) and composite mode.

(4) Vehicle-mounted mobile mapping system, also known as mobile road mapping system (MMS), is based on vehicles, and integrates GPS receiver, video sensor CCD and inertial navigation system INS, so as to quickly collect terrain data of roads and both sides for mapping when vehicles are driving.

Extended data:

Specific requirements for step measurement of engineering topographic mapping;

(1) total station digital recording mode:

1 instrument setting: the instrument alignment deviation is not more than 5 mm, and the plane position difference is not more than 0.2mm on the drawing, and the height difference is not more than the basic vertical interval of 1/5.

2. Data acquisition: collect the three-dimensional coordinates of the fracture point.

Topographic map elements are divided into topographic elements (features, landforms, symbols), annotation elements and mathematical elements.

Geomorphological features: such as hilltops, saddles and other variable slope points; Geological line; Upper and lower elevation points of scarp slope; Elevation points with a certain density, etc.

Feature points: such as inflection points of buildings and envelope structures; Road, scarp and inflection point of water system; The inflection point of gardens and other places; High voltage poles, etc.

Data record: coordinate data, dot number, code, drawing signal and sketch.

4 data preprocessing: import data into computer, check data errors and generate graphic data.

5. Data editing: interactive editing of graphic data, construction of DTM (Digital Terrain Model), generation of contour lines, and graphic stitching (geometric stitching and logical stitching).

6 topographic map making: rectangular framing, generally 50×50cm or 40×50cm, cutting and trimming.

(2) Digital photogrammetry and remote sensing mapping

1, the basic requirements of digital camera measurement partition

Determine the minimum span of the partition according to the drawing scale, as large as possible;

The division boundaries are consistent with the outline of the map;

Generally, the terrain elevation difference in the sub-area is not greater than 1/4 of the relative height; when the aerial photography scale is greater than or equal to 1: 7000 (or the ground resolution is less than or equal to 20cm), it is generally not greater than1/6;

The landscape contrast and landform types in the zoning should be as consistent as possible;

When the topographic features are obviously different, the map partition can be broken with the permission of the user;

The safe distance and height in front of the aircraft side should be considered.

Using GPS to assist aerial photography to ensure the consistency of partition boundaries and encrypted partition boundaries, or one photography partition can cover multiple complete encrypted partitions;

2. Technical requirements for low-altitude remote sensing:

The relative altitude does not exceed 1500m, and the highest altitude does not exceed 2000m；;

The battery life is longer than 1.5 hours;

The UAV landing site should be more than 0 km away from military and commercial airports10.

When unmanned aerial vehicle parachutes, it should be ensured that there are no non-working personnel within 50m of the scheduled landing point of the unmanned aerial vehicle, and no one can stand in the 90 sector area within 200m in front of the launcher.

The average trouble-free working time of the system should be more than 200 hours.

When designing the flight altitude, the aerial photography of UAV should be higher than the shooting area and the highest point of the air route1100mm.

References:

Baidu encyclopedia-topographic map