Some standard content:
ICS07.040
iiiKAa~cJouakAa
National Standard of the People's Republic of China
GB/T14912-2017
Replaces GB/T14912-2005
1:5001:10001：2000
Specifications for 1: 500 1: 1000 1 : 2 000 field digital mapping2017-12-29 Issued
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Standardization Administration of China
2018-07-01 Implementation
GB/T14912—2017
Normative Reference Documents
Terms and Definitions
Preparation and Planning
Root Control Survey
Data Collection
Digital map revision and measurement
Data processing··
Related document preparation
Inspection and acceptance
Results collation and submission
Appendix A (informative appendix)
iiiKAa-cJouaKAa
Data stratification·
GB/T14912—2017
iiikAa~cJouakAa-
The influence of rate and refraction difference. When calculating trigonometric height, the angle should be taken to the second and the height difference should be taken to the centimeter. Table 7
Number of measurements by the middle wire method
Instrument type
6\level measurement
Angle instrument
Trigonometric height
Note 1: 5
Opposite 1
One-way 2
Side length (km).
Vertical angle is poor,
Indicator difference is poor
Note 2Ha-
Basic contour interval (m)
Number of sides.
Note 3: #
Note 4: D
Length of a measuring side (km).
6.4 Supplementary
Technical indicators of trigonometric height measurement of measuring stations
Difference of height observed in opposite directions, difference of height between two
heights calculated in each direction
Closure difference of matching route or loop
Theodolite trigonometric height
Dongshio1Han
Height traverse
±40VDJ
Field digital mapping should make full use of control points and basic points. When the density of the control points is insufficient, the global satellite navigation system RTK measurement method can be used to add measuring stations, and the branch line, polar coordinate method, free station method and other methods can also be used to add them. Regardless of the method used, the mean error of the additional measuring station relative to the adjacent control points should not be greater than 0.1XM×10-(m), and the elevation error should not be greater than 1/6 of the basic contour interval of the survey.
The technical requirements for the global satellite navigation system RTK measurement should be implemented in accordance with the provisions of CH/T2009. The technical requirements for the branch line and polar coordinate method measurement should be implemented in accordance with the relevant provisions of 6.2.2 and 6.2.3. When the free station method is used for measurement, the number of known points observed should not be less than two. The horizontal angle and distance are observed in one round, and the error of half a round should not be greater than 30", and the error of the distance reading should not be greater than 20mm. The difference between the calculated horizontal angle and the observed horizontal angle in each direction measured by the free station method should not be greater than 40° at 1:500, and should not be greater than 20″ at 1:1000 and 1:2000 according to the surveying scale. Data collection
7.1 Work organization
7.1.1 Field digital mapping generally organizes work and data in a unified manner based on the surveyed area (survey area). When the survey area is large or conditions permit, it can also be divided into several relatively independent zones according to natural strip features (such as street lines, riverside lines, etc.) as boundary lines.
7.1.2 The data organization, data processing and operations of each zone should be coordinated with each other. There should be no contradictions in data collection and processing within and between zones, and data overlap or missed measurements should be avoided. 7.1.3 When there are features that cross different zones, the features should be completely collected in a certain zone. 7.2 Preparations
7.2.1 Before starting to survey the survey area, the standard sectional map numbers in the survey area should be compiled, and the survey area sectional information should be established, such as the sectional map number, the coordinate range of the gallery points, the survey scale, etc. 7.2.2 Before daily surveying, the control point data should be calibrated. The connection between the total station and the electronic hand, the communication between the global satellite navigation system RTK base station and the mobile station, the mapping software or data acquisition software and all its communication connections should be tested and checked to ensure that they can be used only after they are running correctly.
iiiKAa~cJouaKAa-
7.2.3 Generally, relevant metadata should be recorded before daily measurement. 7.3 Collection methods and requirements
7.3.1 Collection methods
GB/T14912—2017
The collection of elements can be carried out by global satellite navigation system RTK measurement, polar coordinate method, offset method, intersection method and other measurement methods. When it is difficult to set up stations inside the neighborhood, comprehensive methods such as geometric mapping can also be used. The elevation value of the element can be measured by global satellite navigation system RTK measurement, trigonometric height measurement and leveling measurement. 7.3.2 Global satellite navigation system RTK mapping When using global satellite navigation system RTK mapping, the provisions of CH/T2009 shall be followed. 7.3.3 Total station mapping
7.3.3.1 Mapping method
Total station mapping can adopt coding method, sketch method or real-time mapping method integrating indoor and outdoor work. 7.3.3.2: Total station setting and station orientation check The requirements for total station setting and station orientation check are as follows: a) The centering deviation of the instrument is not more than 5mm;
Use the more distant station point (or other control point) as the station orientation point to calibrate the direction (starting direction), and use another station point (or other control point) as the check point. The calculated plane position difference of the check point is not more than 0.2×M×10-(m); the elevation difference should not be greater than 1/6 of the contour interval;
At the end of data collection at each station, the calibration direction should be re-checked. If the test result exceeds the limit error specified in 7.3.3.2b): The results of the broken points measured before the test C
should be recalculated, and no less than two broken points should be tested. 7.3.3.3 Requirements for recording of scattered points
The format of scattered point observation records can be determined by the user. The record content should include the observation point number, code, connection type, coordinate information (work,,), etc. Other horizontal survey station numbers, instrument height, beacon height, slope distance, vertical angle, horizontal angle, connection points, etc. can be recorded according to actual requirements. 7.3.3.4 Mapping requirements
Mapping should meet the following requirements
When the sketch method is used, it is advisable to draw sketches according to the survey stations: a)|| tt||When using the coding method, it is advisable to use a general coding method. You can also use the coding system established by the software's custom functions and extended functions to operate;
When using the real-time mapping method of indoor and outdoor work integration, the attributes, connection relationships and logical relationships of the measuring points should be established in real time: When measuring, the area boundary should be measured outside the map 10mm: d)
The collected data should be checked and processed, and the invalid data should be deleted or marked, and the data with excessive errors should be re-measured, and the missed data should be supplemented. e
For the checked and modified data, it should be communicated with the computer online in time, and the original data file should be generated and backed up. 7.4 Observation Records
7.4.1. The element classification and coding used in data collection can be specified by yourself, but after the data processing is completed, the element classification and coding used should comply with the requirements of GB/T13923.
7.4.2 The field data record file should be a text file, and its format can be specified by yourself. When submitting the results, the format description should be attached. GB/T14912—2017
7.5 Collection requirements
iiiKAa~cJouaKAa-
7.5.1 The elements collected should be free of distortion, displacement and omission. 7.5.2 When point elements (independent features) can be expressed in proportion, they should be collected according to the actual shape. When they cannot be expressed in proportion, their positioning points or line points should be accurately determined. Point elements with direction should first collect their positioning points, and then collect their direction points (lines). 7.5.3 Linear elements with multiple attributes (the common edges of linear features and surface features, and the overlapping parts of the boundary lines of linear features and surface features) should only be collected once, but the relationship between the elements should be handled well. 7.5.4 When collecting linear elements: measurements should be carried out according to their changes. When they are more complicated, the density of feature points can be appropriately increased to ensure accurate fitting of the curve.
7.5.5 When the collection of broken points and control measurement are carried out simultaneously, the coordinates of the broken points should be calculated based on the coordinates of the control points after adjustment. When the control measurement results are checked beyond the limit, the measurement control points should be re-measured and the coordinates of the broken points should be recalculated. 7.5.6 When collecting data, in addition to the provisions of 7.3, the non-symbolized results should collect the required attribute data according to the requirements of GB/T20258.1 and the technical design book, and no omissions should be made. Attribute items, attribute data types, codes and record formats should comply with the provisions of GB/T20258.1 and the corresponding technical design book and related technical documents. 7.5.7 When the data results contain digital elevation models, feature points, feature lines, boundary lines, water area lines and surfaces, and elevation inference areas should also be collected. The specific content and collection requirements are as follows: a) Feature points include topographic feature points and landform mutation points such as hilltops, depressions, saddles, gully cores, valley bottoms, road intersections, etc. The elevation accuracy of the collected feature points should be consistent with the accuracy of the elevation annotation points. b) Characteristic lines include ridge lines, valley lines, fault lines, and topographic changes such as the upper and lower edges of artificial landforms such as dams, trench frames, quarries, and large steep slopes. The elevation accuracy of the collected characteristic lines should be consistent with the accuracy of contour lines. Boundary lines refer to the boundary lines of structures and roads. The structure should collect its drainage line as the boundary line, and the road should collect the boundary according to the slope change point, and measure the corresponding elevation value. Different boundary lines can be adjacent, but should not overlap or intersect. Water area lines include double-line rivers, planar static water areas, etc., double-line rivers should collect the upper and lower bank lines according to actual conditions, and the elevation of the double-line river water edge line should be based on the measured value. If necessary, the elevation value interpolated by the elevation of the upstream and downstream water points should be used for rationality check. The elevation value should decrease in gradient and have a reasonable relationship. The surface static water area should collect the water edge line and assign a uniform elevation value. The assigned elevation should be coordinated with the surrounding elevation and meet the requirements of contour elevation accuracy. e) The elevation inference area should collect the range line according to the inference area. 7.6 Selection of element content
In addition to complying with the relevant provisions of GB/T20257.1, the following provisions shall also be observed for the representation methods and selection principles of various types of landforms and geomorphic elements:
Water systems and their annexes shall be collected according to their actual shapes. The direction of water flow shall be measured for rivers: the elevation of the top edge and bottom of the canal shall be measured: a)
The elevation of the top and the foot of the slope of embankments and dams shall be measured: the elevation of the outlet and well platform of the spring shall be measured, and the depth from the well platform to the water surface shall be marked. b) All types of buildings, structures and their main ancillary facilities shall be collected, and the wall foundation shall be used as the basis for the collection of houses. Residential areas may be measured according to the scale of the map or require appropriate integration. When the convexity and concavity of the outline of buildings and structures is less than 0.5mm on the map, they can be integrated. Highways and other two-lane roads shall be collected according to the actual width and scale. When collecting data, the green space or isolation C
belt within the scope should be collected at the same time, and the passing relationship between roads of all levels should be correctly indicated. d) The turning points of the above-ground pipelines should be measured. When the support poles and auxiliary facilities of the straight part of the pipeline are dense, they can be appropriately included. The landform is generally represented by contour lines. When the landform with obvious characteristics cannot be represented by contour lines, it should be represented by symbols. Elevation points are generally selected from obvious landforms or terrain feature points. Elevation points should be measured and recorded at the top of the mountain, saddle, depression, ridge, valley bottom and inclination change. The density of the collected elevation points should comply with the provisions of 7.7. Slopes and steep steps can be discarded when the height ratio is less than 1/2 of the basic contour interval or the length on the map is less than 5mm. When the slopes and steep steps are dense, they can be appropriately selected.
iiiKAa~cJouaAa
GB/T14912—2017
) For cultivated land planted with different crops in different seasons of the year, the main crops in summer shall prevail; when the land class boundary coincides with the linear features, the data shall be collected according to the linear features.
h) Names of residential areas, government agencies, schools, mountains, rivers, etc. should be marked. 7.7 Elevation point density
The spacing between elevation points should generally be implemented in accordance with the provisions of Table 8: The density of sampling points should be increased at the topographic lines and fault lines according to the changes in the terrain. The elevation points in flat areas can be appropriately relaxed, but the minimum should not be less than 5 points per 100cm. Table 8 Spacing between topographic points
Scale
Average spacing between topographic points
Measuring length of scattered points
1:1000
Unit: meter
1:2000
The measuring length of scattered points should generally be implemented in accordance with the provisions of Table 9. In special cases, under the premise of ensuring the accuracy of the broken points, the distance measurement length of the broken points can be relaxed by 1 times according to the provisions of Table 9. Table 9 Distance measurement length of broken points
Scale
Ground feature point
1+1000
1+2000
Data reading
Measurement length
Topographic point
Unit is meter
When collecting data, the horizontal angle and vertical angle are read to the minimum division of the degree plate, the height of the beautiful mark is measured to centimeters, and the distance reading is read to millimeters. The zero check and vertical angle index difference should not be greater than 1.
7.10 Sketch drawing
7.10.1: When drawing sketches in digital measurement mode, the collected ground features and landforms shall be drawn in accordance with the provisions of GB/T20257.1 in principle. Complex graphic symbols can be simplified or defined by themselves. However, the terrain code used in data collection should correspond to the symbol drawn on the sketch.
The sketch should be marked with the point number of the measured point, and the marked point number should be consistent with the point number in the data collection record. 7.10.3
The location, attributes and mutual relationship of the elements on the sketch should be clear and correct. Various names and attributes of features that need to be annotated on the topographic map should be clearly marked on the sketch. 7.10.4
8·Digital map revision and measurement
Preparation work before revision and measurement
Before revising and measuring digital maps, field surveys should be carried out to understand the changes in terrain elements and the distribution, grade and integrity of various control points. Then, the revision and measurement scope shall be determined based on the survey results, and a revision and measurement plan shall be formulated. 11
GB/T14912—2017
8.2 Revision and measurement methods and requirements
iiiKAa~cJouaKAa-
8.2.1 When re-surveying new residential buildings, independent tall buildings or complex landforms that have changed, when the scope of change is large or the control of the surrounding features is insufficient, the basic control points shall be re-surveyed before re-surveying. 8.2.2 The revision work should use the original adjacent control points or the re-surveyed control points. The accuracy of the revised feature points should meet the accuracy requirements of the feature points of the corresponding scale topographic map in 4.2.1. 8.2.3 When the features in the local area do not change much, the verified feature points can be used for revision. The position error between the revised feature and the adjacent original feature should not be greater than 0.6×M×10 (m). The revised feature points can no longer be used as the basis for the revision of new features. 8.2.4 The elevation points should be measured from the adjacent elevation control points. For a small number of elevation points in local areas, three fixed elevation points can be used as the basis for supplementary measurement. The elevation difference of the supplementary measurement result should not exceed 1/5 of the contour interval, and the average value should be used. 8.2.5
When revising and measuring, if it is found that there are already features in the original data, or if there are obvious errors or gross errors in the statements, annotations, and stratification, they should also be corrected. 8.2.6
The deletion of the terrain elements that disappeared during the revising and measuring, the element relationship processing and the edge processing should be carried out in accordance with the relevant provisions of GB/T14268. 8.2.7
After revising and measuring each map, the revising and measuring situation should be recorded, and the data before revising and measuring should be archived with version identification for reference during the next revising and measuring. Data processing
9.1 Arrangement and inspection of data
9.1.1 Field data (including data recorded by hand in field records) should be processed in a timely manner to form blocks. Arrange and check the attribute data, and check and verify it against the actual situation.
9.1.2 When a contradiction is found in the comparison and inspection, such as errors in the sketch drawing, the sketch should be modified according to the actual situation: if there are errors in the data record, the measurement point number, terrain code and information code can be modified, and the observation data such as horizontal angle, vertical angle, distance height, standard height, etc. in the record shall not be modified. If there are errors in the observation data, it should be reworked and re-measured.
9.1.3 Delete or mark the invalid record.
The modified data should be saved in time and backed up. 9.1.4
9.2 Non-symbolic data processing
General provisions
Data processing should generally meet the following requirements: a)
Original field survey data shall not be modified;
The encoding of Chinese character information shall comply with the provisions of GB/T2312-1980; b
Graphic and attribute data processing shall be uniformly carried out in units of survey areas or sub-areas; d
When data is divided into sections according to standard sheets or special requirements, the topographic features shall be consistent in geometry, attributes and topological relationships between the current sheet and the adjacent sheets;
Line drawing shall be smooth, natural, clear, without squeezing and duplication. 9.2.2 Graphic data
Graphic data processing should meet the following requirements: b) Point elements should be accurately positioned:
b) Surface elements should be closed, without hanging nodes or overshooting: a surface element should be uniquely identified; Line elements should be continuous, there should be no hanging at the intersection of lines, line strokes should not be incorrectly interrupted, repeated or turned back, and elements that need to be connected should remain connected;
d) Elements with direction should have the correct direction. 12
9.2.3 Attribute data
iiiKAa~cJouaKAa-
Attribute data should meet the following requirements:
a) Feature code should comply with the requirements of GB/T13923: GB/T14912—2017
The attributes describing the characteristics of each terrain feature should be complete, and the feature attributes should comply with the requirements of GB/T20258.1 and the technical design documents, and there should be no omissions:
The field name, field type, field length, field sequence, attributes and attribute values in the attribute table of center point, line and surface features should be correct. 9.2.4 Data stratification
Data stratification should be based on the major feature categories divided by GB/T13923 and in accordance with the provisions of the technical design. When there is no clear provision in the technical design, the stratification and layer name code can refer to Appendix A. Data stratification should be correct, without duplication or missing layers. 9.2.5 Edge joining
The edge joining error of the geometric figures of the elements shall not be greater than 242 times the error in the plane and elevation of the corresponding scale topographic map specified in h) and i) of 4.2.1, and the attributes of the elements shall be consistent and the topological relationship shall be correct. 9.2.6 Contour processing
Contour processing shall meet the following requirements:
No more than two contour intervals shall be used on a map:a)
Contours shall be processed in units of survey areas or sub-areas. The contours of non-symbolized results shall be continuous and seamless, and shall not be deformed due to the division of the plane:
When generating contours, the direction of the topographic lines shall be determined, and the fracture lines shall be closed, and then a rigorous mathematical model shall be used for calculation:If the basic contour interval cannot display the landform features, half-interval contour lines shall be added:d
After the contours are generated, they shall be checked against the actual situation, and any errors found shall be corrected in a timely manner. 9.3
Symbolized data processing
Data processing, symbol representation and specifications of symbolized data shall comply with the provisions of GB/T20257.1. In addition to complying with the provisions of GB/T20257.1, data processing shall also meet the following requirements: a) Symbols of various elements should be expressed in a physical form: b) Buildings built on steep slopes or slopes should be drawn according to their actual positions. When the steep slope cannot be drawn accurately, they can be shifted and a 0.3mm interval should be left:
When buildings suspended over water (such as houses) coincide with the water edge, the buildings should be drawn as usual and the water edge should be interrupted: d) When point features coincide with other features such as houses, roads, and water systems, the symbols of other features can be interrupted and a 0.3mm interval should be left between them to maintain the integrity of independent symbols: Iron When the road and highway (or other roads) intersect horizontally: the railway symbol is not interrupted, and the highway (or other road) symbol is interrupted: e
When there are multiple lines on the same pole, the main line is indicated, and the directions of various lines should be continuous, and the line types should be clear; the power lines and communication lines in the urban built-up area may not be connected, but the connection direction should be drawn at the pole: g)
When the water edge line coincides with the steep slope, the steep slope edge line can be used to replace the water edge line: When the water edge line coincides with the foot of the slope, the water edge line should still be drawn at the foot of the slope:
h) The elevation point annotation is generally annotated to the right of the point, with a spacing of 0.5mm from the point. 9.4 Generation of digital elevation model
The generation of digital elevation model shall be carried out according to the following requirements: GB/T14912—2017
iiiKAa~cJouakAa-
Digital elevation model should be made by survey area or sub-area. The feature data, boundary lines, water area lines and surfaces, elevation inference areas, and contour lines in the partition should be connected. The data after the connection should be in the correct position, reasonable shape, complete connection, and consistent attributes, and the data after the connection should be used to construct TIN (irregular triangulated network).
b) After constructing TIN, there should be no abnormal triangles when superimposing the TIN graphics with the base map data. For unreasonable triangles, points should be added internally and then TIN should be reconstructed; the line network perspective map generated by TIN should have no gross error points, lines or areas due to elevation anomalies. e
The digital elevation model should be generated by TIN interpolation according to the grid spacing specified in CH/T9008.2. The offset between the contour lines generated by the digital elevation model and the contour lines of the original map should not be greater than 1/2 of the basic contour interval. The digital elevation model should be cut in sections according to the provisions of CH/T9008.2. e) Adjacent digital elevation models in different partitions should be connected. When processing the edges, compare the elevations of the grid points with the same name at the edge. When the error in the elevation is less than 2 times the error in the elevation, take the average value as the elevation value of the grid points with the same name. When it is greater than 2 times the error in the elevation, check and modify it to make the error in the elevation meet the requirement of not more than 2 times the error in the elevation, and then take the average value, so that the elevation values of the grid points with the same name at the edge are consistent, and the elevation changes meet the characteristics of terrain continuity. 9.5 Organization and format of data files
9.5.1 After the data processing is completed, the data files should be organized by survey area and stored and managed by map sheet. The organization and naming of files shall be carried out in accordance with the relevant provisions of CH/T9012. 9.5.2 Each mapping software can use its own specified data format to exchange and manage internal data information. The data information exchange format between different systems should meet the requirements of GB/T17798. 10 Production of related files
Produce the metadata of each achievement and fill in the map calendar chain. The content of metadata should comply with the provisions of CHT1007. The content of the map calendar includes the overview of the digital product of the map, the use of data, the completion of the main processes in the collection process, the problems that occurred, the treatment methods, the process quality inspection, the product quality evaluation, etc. The content of metadata and map calendar should be complete and correct. Write the technical summary according to the requirements of CH/T1001. 11 Inspection and acceptance
11.1 General provisions
11.1.1 The technical design should comply with the relevant technical requirements of this standard. 11.1.2 Each process and each work stage in the operation should be self-checked in time after completion. 11.1.3 The quality of the results should be successively checked by the process inspection of the operation department of the surveying and mapping unit, the final inspection of the quality management department of the surveying and mapping unit and the acceptance of the production entrusting party. The inspection and acceptance work at all levels should be carried out independently and should not be omitted or replaced. 11.1.4 The content and requirements of the quality inspection and acceptance of the results of the map control survey and the field data collection results shall be implemented in accordance with the provisions of GB/T24356.
The quality inspection and acceptance of digital line drawings and digital elevation model results shall be carried out in accordance with the provisions of GB/T18316. 11.1.67
Select various types of results for inspection and acceptance in proportion as needed. The inspection ratio is determined by the technical design, and the sample size for acceptance shall be carried out in accordance with the provisions of GB/T18316.
11.2 Accuracy inspection requirements
Plane and elevation accuracy inspection
The accuracy inspection of data results shall meet the following requirements:14
iiiKAa~cJouaKAa
GB/T14912—2017
a) The plane coordinates and elevation of the data results shall be measured according to the accuracy of the measuring station using the field scatter point method. The plane and elevation detection points shall be evenly distributed and shall be randomly selected obvious ground object points (feature points). The number of plane and elevation test points is determined according to the specific conditions such as the complexity of the ground objects. In general, no less than 50 points are selected for each map, and the calculation of the mean error is carried out in accordance with the provisions of GB/T24356. The distance between adjacent ground object points is measured with a copper ruler or a distance meter for the accuracy test of the spacing between adjacent ground object points. The number of measured edges is generally no less than 20 for each map, and the calculation of the mean error is carried out in accordance with the provisions of GB/T24356. If gross errors are found in the ground object points and elevation points being tested during the test, they should be re-measured as appropriate. When the mean error calculated by the test in a map exceeds the relevant provisions of h) and i in 4.2.1, the error distribution should be analyzed, and then the adjacent map sheets should be spot checked, and the map sheets with excessive mean errors should be re-measured. d) The test results should be established in statistical tables and field test reports should be compiled. 11.2.2
Testing of edge joining accuracy
Testing methods and requirements for close accuracy are as follows: Testing of edge joining accuracy is done by measuring the distance between the endpoints of the elements at the edge of two adjacent sheets. The deviation value of the unconnected elements a)
should be recorded:
b): Check the natural connection of the edge joining elements in geometry to avoid abrupt and unnatural continuity of the lines at the edge joining; c): Check the consistency of the attributes of the same plane and linear elements at the edge joining, and record the elements with inconsistent attributes. 11.3 Quality Assessment
The quality assessment of the results of the basic control survey shall be carried out in accordance with the relevant provisions of GB/T24356. The quality assessment of the results of digital line drawing and digital elevation model shall be carried out in accordance with the relevant provisions of GB/T18316. 12 Results Arrangement and Submission
The results that have passed the acceptance shall be registered and sorted according to the following contents and submitted: Results List:
Water stall route map, basic control results:
Field observation records;
In-house calculation data, such as files and data generated during data processing; digital line drawing data, digital elevation model data, metadata, map and calendar: classification and combination table;
Technical design book:
Technical summary report:
Inspection report:
Acceptance report:
Other data files, drawings, documents and other materials supplemented according to actual needs. GB/T14912—2017
iiikAa~cJouakAa-
Appendix A
(Informative Appendix)
Data stratification
Data stratification is based on the eight major elements specified in GB/T13923, supplemented with place names and annotation classification, and on this basis, stratified according to the three geometric types of points, lines, and surfaces and their subordinate relationships. A.2 The data layer is named with four characters. The first three characters are the abbreviations of the data content. The first character represents the element classification, and the fourth character represents the geometric type of the data. The point is represented by the letter P, the line is represented by the letter L, and the surface is represented by the letter A. A.3 See Table A.1 for data stratification and layer name codes. Data layering and layer name code
Feature classification
Positioning base
Settlement and facilities
Boundary and political division
Data layering
Surveying control point (point)
Coordinate grid (coordinate)
Water system (point)
Water system (line)
Water system (surface)
Water system ancillary facilities (point)
Water system ancillary facilities (line)
Water system ancillary facilities (surface)||t t||Residential area (point)
Residential area (line)
Residential area (surface)
Facilities (point)
Facilities (line)
Facilities (surface)
Railway (line)
Highway (line)
Highway (surface)
Transportation ancillary facilities (point)
Transportation ancillary facilities (line)
Transportation ancillary facilities (surface)
Pipeline (point)
Pipeline (line)||tt ||Boundaries and administrative divisions (points)
Boundaries and administrative divisions (lines)
Provincial administrative divisions (areas)
iiiKAa~cJouaKAa
Table A.1 (continued)
Element classification
Boundaries and administrative divisions
Vegetation and soil quality
Place names and notes
Data stratification
Municipal administrative divisions (areas)bzxz.net
County administrative divisions (areas)
Village and town administrative divisions (areas)| |tt||Other areas (line)
Other area annotations (points)
Landforms (points)
Landforms (line)
Landforms (surfaces)
Landform attachments (points)
Landform attachments (line)
Vegetation (points)
Vegetation (line)
Vegetation and soil properties (surfaces)
Place names and notes (points)
Place names and notes (line)
GB/T14912—2017
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.