Some standard content:
GB/T17942
This standard is compiled in accordance with the relevant provisions and requirements of national standardization, with reference to the relevant provisions of the "National Angle Measurement and Precision Traverse Measurement Specifications" formulated by the State Administration of Surveying and Mapping in 1974, and in combination with the recent development of science and technology and production. Appendix A of this standard is the standard appendix; Appendix B is the reminder appendix. This standard is proposed and managed by the State Administration of Surveying and Mapping. This standard is printed by the Surveying and Mapping Standardization Institute of the State Administration of Surveying and Mapping and the First Geodetic Survey Team of the State Administration of Surveying and Mapping. The main drafters of this standard are: Lv Yongjiang, Lv Hangou, Li Rongchun, Meng Juan.
1 Scope
National Standard of the People's Republic of China
Specifications for national triangulation
Specifications for national triangulationGB/T 17942 -2000
This standard specifies the layout principles, basic accuracy indicators and main technical requirements for wide triangulation; it is applicable to national triangulation, third-, fourth- and regional triangulation, and other triangulation and traverse measurements can also be implemented as a reference. Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB 12898 1991
National third- and fourth-class leveling specifications
GB/T168181997 Specifications for medium and short-range photoelectric distance measurementCH 1001 --1995
CH 1002 -1995
Regulations for the compilation of surveying and mapping technical summaries
Regulations for the inspection and acceptance of surveying and mapping products
CH 1003---1995
Surveying and Mapping Product Quality Assessment Standard
CH/T 1004-1999
CH/T 2004-- 1999
CH/T 2005
JJG 100 1994
JJG 4141994
3 General Principles
Surveying and Mapping Technical Design Regulations
Basic Regulations for Field Electronic Records of Surveying
"Regulations for Electronic Records of Angle Measurements
Measurement Verification Regulations for Total Station Electronic Tachometer Measurement Verification Regulations for Optical Theodolite
3.1 National Triangulation Grades and Layout Principles 3.1.1 National Triangulation Grades
National triangulation is divided into first, second, third and fourth grades. First and second grade triangulation belongs to national basic control measurement, and third and fourth grade triangulation belongs to sub-encryption control measurement.
3.1.2 Principles of the layout of the national triangulation network
The national triangulation network is an important part of the national geodetic control network; the layout of the national triangulation network should follow the principle of hierarchical layout from the whole to the part, from high level to low level.
3.2 The layout form of the national angular network
3.2.1 The layout form of equal triangles
Equal triangulation covers the whole country and is laid out in the form of triangulation locks or continuous triangulation networks; the first-order and second-order triangulation locks should be laid out in the shape of lock rings along the longitude and latitude lines respectively. The lock section length of the lock ring is about 200km. The first-order starting side is determined at the intersection of the lock ring and the lock section. The first-order astronomical longitude, latitude and first-order azimuth are measured at the two end points of the first-order starting side, and the first-order astronomical longitude and longitude are measured at the ··triangulation points in the center of each lock section.
Approved by the State Administration of Quality and Technical Supervision from January to March 2000, implemented from August 1, 2000
GB/T 17942-2000
When laid out in the form of continuous triangulation, an equal starting edge is measured every 200km or so, and the first-order astronomical longitude, latitude and first-order astronomical azimuth are measured at both ends of the starting edge, and the first-order astronomical longitude and longitude are measured at the triangulation points in the middle. 3.2.2 Arrangement of second-order triangulation
The second-order triangulation is laid out in the form of continuous triangulation within the first-order triangulation locking ring, and a first-order starting edge is laid out in the central part of the second-order triangulation, and the first-order astronomical longitude, latitude and astronomical azimuth are measured at both ends of the starting edge. In places where the first-order continuous triangulation is laid out, the second-order triangulation can be omitted, and the third-order or fourth-order triangulation points or triangulation can be directly encrypted.
3.2.3 Layout of third- and fourth-order triangulation
Third- and fourth-order triangulation is an encrypted measurement under the first- and second-order triangulation network. The third- and fourth-order triangulation network is laid out in the form of insertion points or continuous networks.
Where there is no second-order triangulation network, the third- and fourth-order triangulation network can also be laid out directly in the first-order triangulation ring or under the first-order triangulation network.
3.3 Density of national triangulation points
3.3.1 Side length of equal triangulation network
The average side length of equal triangulation network: about 25km in mountainous areas and about 20km in plains. When restricted by terrain conditions, the side length can vary within the range of 15 to 45km. When crossing straits, large lakes and other water systems, the side length is not subject to the above restrictions. 3.3.2 Density of equal angle points
The average side length of the second-order triangulation network: about 9km in urban areas and some industrial and agricultural economically developed areas, about 13km in other areas, and can be appropriately longer in mountainous or desert areas. 3.3.3 Density of third- and fourth-order triangulation points
The side length of the third- and fourth-order triangulation can be determined according to the distribution of the first- and second-order plane control points and actual needs. The side length of the third-order triangulation network can vary in the range of about 4 to 10km, and the side length of the fourth-order network can vary in the range of about 1 to 6km. 3.4 Accuracy of triangulation
3.4.1 Accuracy of the starting side
The relative mean error of the length of the starting side of the first-order triangulation network shall not exceed 1/350,000 of the earth; 3.4.2 Accuracy of astronomical longitude, latitude and azimuth - The mean error of astronomical longitude, latitude and azimuth shall not exceed the provisions of Table 1. Table 1
Accuracy of triangulation
Astronomical longitude
±0:02
Astronomical latitude
The mean error of angle measurement calculated by triangle closure error of each triangulation shall not exceed the provisions of Table 2. Table 2
Mean error of angle measurement
±o”7
±”o
The relative mean error of the length of the weakest side and the mean error of azimuth in each triangulation shall not exceed the provisions of Table 3. Table 3
Relative mean error of side length
Mean error of azimuth
3.5 Basis of national triangulation
1/200,000
1/120,000
1/70,000
Astronomical azimuth
1/40,000
3.5.1 Coordinate system
GB/T17942-2000
The national triangulation adopts the 1980 Xi'an geodetic coordinate system. The basic parameters of the reference ellipsoid used in the 1980 Xi'an geodetic coordinates are: major radius a = 6378140m
Earth gravity constant (including atmosphere) GM = 3.986005×101m/sSecond-order zone harmonic coefficient 12 = 1.08263×103Www.bzxZ.net
Earth rotation angular velocity w = 7.292115×10-5rad/s3.5.2 Height system
The height of the national triangulation adopts the normal height system; it is calculated from the 1985 national height datum; the height of the Qingdao height datum origin is 72.260m
3.5.3 Plane coordinate system
The plane coordinates of the national triangulation adopt the Gauss-Kruger plane coordinate system. The national triangulation points are all calculated with the plane rectangular coordinates of the six-degree zone or three-degree zone of the Gauss plane.
The main meridian longitude of the six-degree zone or three-degree zone starts from 3° east longitude, and the projection zone is divided every 6° or 3° respectively. In each projection zone, the intersection of the main meridian and the equator is used as the origin of the vertical and horizontal coordinates of the plane rectangular coordinates. The projection length ratio of the main meridian is set to 1, and the horizontal coordinate of each point on the main meridian is set to 500,000m.
3.6 Basic technical requirements for national triangulation 3.6.1-First-order triangulation
When a single triangulation lock is used, the triangle should be as close to an equilateral triangle as possible, and any angle should not be less than 40°. When a midpoint polygon or a geodetic quadrilateral or a triangulation network is used, the transmission angle of any calculated route shall not be less than 30°. The sum of the reciprocals of the graphic weights of each lock segment of the first-order triangulation lock should not exceed 100. For some special difficult areas due to terrain restrictions or too long lock segments, the sum of the reciprocals of the graphic weights can be relaxed to no more than 120. If it exceeds 120, the starting side should be measured in the middle of the lock section. 3.6.2 Second-order triangulation
The second-order triangulation network and the first-order triangulation network are connected in the form of a continuous triangulation network. The internal angle of the triangle in the second-order triangulation network shall not be less than 30°. For difficult areas such as complex terrain, the internal angle of individual triangles can be relaxed to not less than 25°.
The distance from the second-order triangulation point to the starting side is generally not more than 12 triangles. 3. 6.3 Third and fourth order triangulation
Third and fourth order triangulation networks are encrypted in the form of continuous triangulation networks or interpolation points or interpolation networks under first or second order control points. The internal angle of any triangle in the third and fourth order triangulation networks shall not be less than 30°. In difficult areas such as terrain restrictions, the internal angle of individual triangles may be relaxed to not less than 25°.
3.6.4 Joint measurement of existing geodetic control points
The first, second, third and fourth order geodetic control network points in the survey area should be overlapped or jointly measured, and the sum of overlapped points and joint measurement points should not be less than three.
3.7 Corner point elevation measurement
3.7.1 Method of triangulation point elevation measurement
The elevation of the triangulation point is obtained by leveling, elevation traverse or triangulation elevation measurement. The triangulation observation sides of all levels of triangulation lock network that need to use triangulation height method to determine the triangulation point elevation should face the observation vertical angle, measure the instrument height and point height, calculate the height difference of round-trip triangulation height, and calculate the elevation of each triangulation point. The triangulation height is calculated from the leveling point or leveling contact point or the elevation traverse point that meets the accuracy requirements. 3.7.2 Main technical indicators of triangulation height measurement The distance from any triangulation height point to the triangulation height starting point is calculated by the triangulation height deduction side and shall not exceed the provisions of Table 4. 287
Triangulation point level
GB/T17942-2000
Deduced side number
The error of the elevation of each level of triangulation point after triangulation height adjustment shall not exceed the provisions of Table 4. 4 Technical design and point selection
4.1 Technical design
4.1.1 Basic requirements for technical design
The error in the elevation of the triangulated points after adjustment,
Before the triangulation survey, technical design should be carried out to obtain the optimal layout plan of the triangulated point network. The format, content, requirements and approval procedures of the technical design document shall refer to CH/T1004.
4.1.2 Data collection
Before the technical design, all relevant data in the survey area should be fully collected for analysis and research and field survey, and then the drawing design should be carried out and the technical design document should be written.
4.1.3 Design on the map
The design on the map should mark the positions of the existing plane and elevation control points and the positions and observation directions of the newly designed triangulated points, as well as the joint survey direction and route with the existing plane control network and the existing elevation control network. 4.2 Site selection
4.2.1 Requirements for the location of triangulation points of each class
α) The selected triangulation points should be easy to expand, and the planned observation direction should have good visibility. The sight line should exceed and deviate from the obstacles at a certain height and distance: in mountainous areas, the first class should not be less than 4m, and the second class should not be less than 2m; in plain areas, the first class should not be less than 6m, the second class should not be less than 4m, and the fourth class should not be less than 4m. The principle of ensuring clear imaging and convenient observation is that the height of the sight line should be determined in the direction of the fourth class. The growth of the height of trees and crops must be taken into account when determining the sight line height. The sight line should try to avoid passing along the slope or river bank. When the sight line passes through rice fields, grasslands, deserts, Gobi, swamps, lakes, large forests, large cities, and industrial and mining areas, the sight line height of the first class should not be less than 8m, and the second class should not be less than 6m.
b) Triangulation points should generally be selected on commanding heights that are convenient for marking and observation, and the marks can be preserved for a long time after burying stones. The point should not be less than 50m away from roads, railways, and rivers, and not less than 120m away from high-voltage lines. ) The two end points of the starting side and the center of the lock segment must be determined on the triangulation point of the astronomical longitude and latitude. If it is inconvenient to conduct astronomical observations, the location of the astronomical stupa should be selected. The distance from the astronomical stupa to the triangulation point should not be less than the altitude of the point, but not more than 60m, and it should be convenient to directly determine the center element of the astronomical stupa. The two end points of the starting side also need to determine the astronomical azimuth. For this reason, the astronomical stupa should be set on the direction line of the starting side as much as possible. The deviation should not be more than 1me
4.2.2 Determination of corner point names
Triangulation points should generally be named by village names, mountain names, and place names; transliteration should be used in ethnic minority areas; when place names cannot be found in desert areas, they can be named according to terrain features or indicated by point numbers. When new and old points overlap, the old point name is generally used. If the original village name, mountain name, or place name has changed, the old point name should be attached to the new point name in brackets. When there are identical point names in the triangulation points of the same triangulation lock or the same 1:100,000 map, they must be distinguished. The name of the roll call must be written accurately and formally, and the simplified Chinese characters used shall be subject to the laws announced by the State Council. 4.2.3 Azimuth Points
Azimuth points can be set as needed for triangulation points of various levels in plain areas. There shall be no less than 2 azimuth points. The distance from the azimuth point to a corner point shall be S
GB/T 17942---2000
500~~1000m; the angle between the directions of two azimuth points on the same triangulation point shall not be less than 60. Azimuth points shall be selected in places where the target is obvious, easy to find, convenient to observe, and can be preserved for a long time. Permanent fixed signs shall be set for the azimuth points.
If the base of a triangulation point can be directly seen from the ground of the triangulation point, then the triangulation point can be used as the azimuth point. 4.2.4 Triangulation Point Records
The first, second, fourth and fourth corner points shall all be filled in the triangulation point records in the A1 format. 4.2.5 Point Utilization
The existing horizontal control points and elevation control points of various levels in the survey area should be used or jointly surveyed as much as possible. The relevant utilization or joint survey conditions should be recorded and explained in detail in the point record and technical summary. Points where the markers are partially or completely damaged should be reburied or reburied according to the highest level requirements of the new survey point and the old point. If the new point is a first or second level point, the old marker is one layer or layers, and they are all complete and stable and can be preserved for a long time, and the marker specifications are not lower than the standards of the fourth level points in this specification, it is not necessary to rebury it.
If the new point is a third or fourth level point, the old marker is one layer and is solid and complete and can be preserved for a long time, it is not necessary to rebury it. All old points that do not meet the requirements of this specification must be reburied with new markers, and the marking centers of the new and old markers should overlap as much as possible. It is not allowed to bury other markers nearby.
When using old points, the "Registration Form for Overlapping Use of Old Points" and "Record Form for Re-burying Stones of Old Points" should be filled in according to the content and format of A2.1 and A2.2, and the relevant dimensions should be accurately measured.
4.2.6 Triangulation Points for Joint Leveling
When selecting points, the joint survey route and joint survey point names of the triangulation points designed for joint leveling should be recorded in the position description of the points, and explained in the technical summary.
5 Marking of Triangulation Points
5.1 Basic Requirements for Burying Stones for Marking
a) Permanent surveying marks should be established for triangulation points of all levels. b) The marker stone is a permanent point mark of the triangulation point. The center of the marker stone should be embedded in the center mark, which represents the center position of the triangulation point. c) The standard markers to be constructed must be in a straight shape, the center of the marker stone and the circle should be parallel to the plumb line, and the structure should be firm; the inner frame and the base plate structure should fit tightly; the base surface should be flat; and the inner and outer frames should not touch each other. The center of the circular cylinder, the center of the light-returning platform, and the center of the marker stone should be located on the same vertical line, and the maximum deviation from the vertical line of the center of the marker stone shall not exceed 0.1m. l) The sight lines in the first and fourth observation directions should be away from the slot column, and the distance should be not less than 0.2m. The sight lines in the third and fourth observation directions should be away from the slot column at a distance of not less than 0.1m.
e) The name, grade, construction unit, and construction year and month of the triangulation point should be marked with colored paint at the appropriate position of the slot column; for piers without external frames, they should be written on the south side of the instrument pier with red paint. f) When making and burying the marker stone, the point position of the point should be explained, and the relevant height and relevant data of the cross-section diagram of the marker stone should be clearly filled in. g) After the completion of the marker stone burying, the local government should go through the procedures for entrusted custody of the survey mark. 5.2 Types of survey marks
The types of survey marks on triangulation points of various grades shall be generally named as follows: a) Ordinary mark: a wooden tripod or quadrilateral mark without an inner frame; b) Steel ordinary mark: a steel tripod or quadrilateral mark without an inner frame; c) Concrete ordinary mark: a tripod mark without an inner frame made of reinforced concrete; d) Composite mark: a wooden tripod or quadrilateral mark with an inner and outer frame connected; c) Double cone mark: a wooden tripod or quadrilateral mark with an inner and outer frame not connected; f) Steel mark: a standard mark made of steel with an inner and outer frame; g) Pier mark: a cylindrical mark added to an instrument pier built of concrete, natural stone, brick or wood; 289
GB/T 17942-2000
h) Native tree markers - in forest areas, native trees are used to remove the treetops and use the branches as markers for the external frame slot columns; i) Horse frame markers - an internal frame of about 1.5m high is built with steel or wood, and a circular standard marker is added; j) Movable markers - movable steel or wooden markers. 5.3 Marking stones and center marks
5.3.1 Marking stone types
The types of triangulation point markers are generally named as follows: a) First and second class triangulation point markers;
b) Third and fourth class triangulation point markers;
c) Triangulation point markers in rocky areas;
d) Triangulation point markers in frozen areas;
e) Blue corner point markers in desert areas;
f) Triangulation point markers in special difficult areas.
5.3.2 Materials of marker stones
Triangular point marker stones are generally made of concrete, but can also be replaced by hard stones such as granite and bluestone of the same specifications. 5.3.3 Requirements for marker stone burial
a) Concrete marker stones buried in saline-alkali areas must be coated with asphalt to prevent corrosion. b) When burying marker stones in areas with soft soil, high groundwater levels or swamps, in addition to choosing a good burial site as much as possible, a concrete base layer should be poured under the flat stone.
c) When burying stones, the marking centers of each layer of marker stones must be strictly on the same plumb line, with a deviation of no more than 3mm. Use a steel tape measure to measure the vertical distance between the surfaces of each layer of marker stones, and fill in the marker stone cross-section diagram of the point mark, with the result taken to centimeters. 5.3.4 Steel pipe mark
The upper end of the steel pipe should be welded closed, and the center mark should be engraved or embedded. The outer wall of the steel pipe should be painted with sticky asphalt, and wrapped with cloth or other materials, and painted with asphalt, the thickness of which should not be less than 3mm. The steel pipe should be filled with concrete to prevent corrosion of the inner wall of the steel pipe. 5.3.5 Center mark
A center mark should be embedded in the center of the pan stone and the column stone of the triangular point marker, and should be placed upright and firmly bonded. The center mark can be made of metal or porcelain material, and its specifications and standards are shown in Appendix A3.1. For the marker stone chiseled from stone, a cross center mark with a cross section of \V\ should be chiseled in the center of the pan stone or column stone, with a line length of about 5cm, and the upper width and depth of the line are about 5mm respectively, and the inside is painted with red paint to replace the porcelain or metal center mark. The center mark of the column stone should be slightly higher than the top of the column stone to facilitate the placement of the water scale. 5.3.6 Reburying the marker stone
When the marker stone overlaps with the old horizontal control point and needs to be reburied, the original stone burying unit or the surveying and mapping management department should be notified. During the reburial, check whether the center marks of the upper and lower marks of the original mark stone are on the same plumb line. When the deviation value is greater than 3mm, the new mark stone shall be buried based on the mark center of the lowest mark stone. Under the principle of ensuring the stability of the new mark stone, try to make the new and old upper mark stone surfaces on the same horizontal plane. During the reburial process, the height difference between the new and old upper mark stone surfaces and the height from the relevant parts of the mark stone to the column stone surface shall be measured. The words "Reburial" shall be marked on the reburied mark stone surface with red paint. After reburying the mark stone, fill in the "Old Point Reburial Record Form" according to A2.2. 6 Horizontal Angle Observation
6.1 Angle Measuring Instruments
6.1.1 Instruments, Observation Methods and Number of Measurements Used in Triangulation at All Levels The instruments, observation methods and number of measurements used in horizontal angle observations for triangulation at all levels shall be implemented in accordance with the provisions of Table 5. 290
Type of instrument used
6.1.2 Inspection of theodolite
GB/T 17942--2000
Direction right of full combination angle measurement method: n·m
36（35)
42(40)
24(25)
30(28.32)
Number of measurement rounds of direction observation method
\: Number of directions
on, number of measurement
The theodolite used for horizontal angle observation should be inspected before use. The inspection items, inspection methods and tolerances as well as the calibration cycle shall be carried out in accordance with the relevant provisions of JJG414 and JJG100. 6.2 Basic requirements for horizontal angle observations at all levels
6.2.1 Instrument placement
When observing first-order and second-order corner points, the instrument should be placed on the instrument stand. When the instrument is placed on the tripod for observation under the normal mark for the second, third and fourth triangulation points, according to the soil conditions, take footing or other measures to ensure that the instrument has a stable observation environment. 6.2.2 Instrument and operation requirements
a) The focal length of the telescope should be adjusted in advance for the horizontal angle of observation, and it should remain unchanged during the same measurement; try not to use the vertical brake and fine-motion screw for aiming at the target; when using the horizontal fine-motion screw or the eyepiece micrometer to aim at the target and the micrometer screw to align the graticule, the final rotation should use the screw-in direction.
b) During the observation process, if the absolute value of the double collimation axis error (2C) is found to be greater than 20\ for DJ07 and DJ1 instruments, and greater than 30\ for DJ2 instruments, the current measurement is invalid and should be corrected before continuing the observation. c) During the observation process, the instrument should be kept horizontal and the bubble of the level on the upper part should deviate from the center. For DJ07, the maximum value should not exceed 1.5 grids, and for DJ1 and DJ2, the maximum value should not exceed 1 grid.
6.2.3 Vertical axis tilt correction
When the vertical angle of the sighting point exceeds ±2° for the first class and ±3° for the second class, the vertical axis tilt correction should be added to the observation direction value. When observing this direction, the position of the bubble of the level on the sighting part must be read and recorded to determine the tilt component of the vertical axis in the horizontal axis direction to obtain the direction correction value.
The change in the length of the bubble of the level due to reading errors and other reasons in the same measurement round shall not exceed 0.6 grids. Generally, vertical axis tilt correction is not added for the third and fourth class triangulation observations. 6.2.4 Sighting targets for various levels of horizontal angle observations For triangulation observations, the luminous mark (i.e., return light) is used. For the second, third and fourth class blue angle observations, the sighting circle, the center column or other stable sighting mark is used. 6.2.5 Selection of observation time and requirements for the number of time periods Horizontal angle observations of various levels should be carried out when the visibility is good, the image is clear, and the sighting can be accurate. a) There should be at least three time periods for observing first-order triangulation points, and the number of basic measurements in each time period should not exceed 2/5 of the total number of basic measurements. The number of measurements for any single angle in a time period should not exceed 1/2 of the total number of measurements, and it is not advisable to observe the same single angle continuously (except for re-measurement).
No requirements are generally made for the ratio of moon and night measurements. When there is a more obvious side refraction effect on the line of sight, the ratio of night measurements is required to be flexible within the range of 30% to 70%, and attention should be paid to selecting favorable observation time periods. 291
GB/T17942—2000
b) There should generally be no less than two time periods for observing second-order triangulation points, and the number of basic measurements in each time period should not exceed 2/3 of the total number of basic measurements. In some special cases, the measurements can also be completed in one time period. c) Morning, afternoon and night are each a time period. 6.2.6 Zero direction selection and direction numbering
Before observation, the directions on the point should be numbered. You can choose any direction with a clear target as the first direction (i.e., zero direction), and then number it in clockwise order as 2, 3, ... 1. When measuring lock, always take the leftmost direction as the zero direction. 6.2.7 Torsion mirror observation mark
When using the 1DJ07 instrument to measure the first degree, a torsion mirror observation mark should be set at a distance of 1 to 1.5 km from the point. 6.3 Preparation of observation dial table
6.3.1 Principles for preparing observation dial table
When using an optical theodolite for observation, the various measurements of horizontal angle observation should be evenly distributed on different positions of the dial and micrometer. a) Before observation, the basic dial position table should be compiled first, and then the observation dial position table should be calculated to determine the starting direction reading of each angle or angle group observed on the point.
b) The basic degree disk position is the degree disk position relative to the first direction (zero direction) determined on the triangulation point. It consists of three parts: degree scale, minute scale and second scale on the degree disk. c) When the starting direction of the observed angle or direction value is not the 1st direction, but the nth direction, the basic degree disk position should be added with the approximate value of the angle (1, \) (to the nearest degree) to become the observed degree disk position. For the angle or direction group whose starting direction is the 1st direction, its basic degree disk position is the observed degree disk position. 6.3.2 Compilation of the observation disk position of the direction observation method a) The calculation formula for the observation disk position of the kth round of DJO7 and DJ1 instruments is 180(-1) + i(k-1) +
In the formula: m-the number of rounds specified by the triangulation point level; k-the serial number of the round (k1.2.m)
\-the smallest scale on the disk
b) The calculation formula for the observation disk position of the kth round of IDJ2 instruments is: 1) +
180(-1)+#(#-1)+
As the value increases, the second term in the formula is
...(2)
. If the value of (-1) reaches or exceeds 1 degree, the "degree" should be discarded and only the "minute" of the term should be taken. When it is an integer degree, take zero.
6.3.3 Preparation of the observation disk position table for the full combination angle measurement method a) Preparation of the basic disk table
Calculate the number of angles to be observed Tnx(n-1) from the number of directions n at the measuring station
Divide all angles into groups. The angles in the same group cannot have the same direction. The basic disk position of each angle in the group is the same. Then when n is an odd number, n
When n is an even number, (n--1)
Let m be the number of rounds of measurement of a single angle, and calculate
180°+1
Horizontal disk transformation value between each round of measurement
Horizontal disk transformation value between each group =
When calculating 180° and 180% and adding them one by one, both should be calculated as 0°1.Then remove the decimals and take the integer to calculate the basic dial position. m
where: \ is the smallest scale mark
GB/T17942-2000
The basic dial position of the first measurement of the first group is 0°0. The micrometer setting position of each measurement is calculated as follows (k-1) -
Wherein: k is the measurement number (k=1.2..m) b) Calculate the observation degree table
Based on the selected direction 1, observe the approximate horizontal direction values of each direction, and take it to the integer. Add the basic degree position of the observation angle of the left direction that is not the 1st direction to the approximate value of the left direction to obtain the observation degree position 6.4 Horizontal angle and horizontal direction observation
6.4.1 Full combination angle measurement method - measurement operation procedure 6.4.1.1 Operation of DJ1 instrument
a) Aim the instrument at the left target, align the degree plate and Micrometer position (allowing 25\); b) Rotate the sighting part clockwise (or counterclockwise) to accurately aim at the left target, use the micrometer to make the degree disk coincide with the diameter division, read the fixed degree, division and optical micrometer readings twice (coincidence twice, read twice); c) Rotate the sighting part clockwise (or counterclockwise) to accurately aim at the right target, read the readings (the method is the same as item b)); d) Rotate the telescope vertically;
e) Aim at the right target, the operation is the same as item c); i) Rotate the sighting part clockwise (or counterclockwise) to accurately aim at the left target and read the readings (the method is the same as item b). The above operations are one measurement round, and the number of measurement rounds observed by the sighting part in the clockwise and counterclockwise directions in each observation time period should be roughly equal. 6.4.1.2 Operation of IDJ07 instrument
a) Aim the instrument at the target on the left, and align the position of the degree dial and the micrometer according to the observation degree table (allowance is ±5\); b) Rotate the aiming part clockwise or counterclockwise to re-aim at the target on the left. First read the horizontal dial and micrometer readings (overlap the diameter scale twice and read twice), then use the main telescope mirror micrometer to accurately aim at the national standard three times and read the readings, then use the deflection observation mirror eyepiece micrometer to aim at the mark three times and read the readings; 1) Rotate the aiming part clockwise or counterclockwise, aim at the right self-marker, use the telescope eyepiece micrometer to aim at the self-marker twice and read the readings: then use the deflection mirror to aim at the mark three times and read the readings, then read the degree dial readings and micrometer readings; 2) Rotate the telescope clockwise or counterclockwise to re-aim the right target, aim and read the readings in the order specified in b); 3) Rotate the aiming part clockwise or counterclockwise to aim at the left target, aim and read the readings in the order specified in c) The above operations are one measurement, and the number of measurement rounds observed by the clockwise and rotating aiming parts in each observation period should be roughly equal. Whether to use the deflection observation mirror is determined by the observer according to the magnitude of the war mark twist. 6.4.2 Operational procedures for one measurement of the direction method
a) Aim the instrument at the zero direction (i.e. the first direction), and align the degree plate and micrometer position according to the observation degree plate table; b) After rotating the alidade 1-2 times in the clockwise direction, accurately aim at the zero direction, and read the degrees, minutes and optical micrometer readings twice (the readings overlap twice and the readings are read twice);
) Rotate the alidade clockwise, accurately aim at the 2nd direction, and read the readings according to the method in b). Continue to rotate the alidade clockwise to observe the 3.4.n directions in turn. Finally, close to the zero direction. d) Rotate the telescope vertically, rotate the alidade counterclockwise for 1-2 times, accurately aim at the zero direction, and read the readings according to the method in b); e) Rotate the alidade counterclockwise, and observe the zero direction in the reverse order of the observations in the first half of the measurement. The above operations constitute one measurement. When the number of directions is less than four, it is not necessary to close to the zero direction. Use DJ07 instrument, set the eyepiece micrometer of the main telescope to zero position, and in the operating room of a measurement round, 6.4.3 Observation of direction observation
GB/T17942..2000
Use the direction method to observe. When the number of directions is more than 6 and it is difficult to observe, it can be considered to divide into two groups of observations, and the number of directions in each group is roughly equal, and there should be two common directions. After taking the median of the two groups of observation results, the difference between the angular values of the common directions shall not exceed ±2m\ (m\ is the mean error of angle measurement at this level). The two groups of observation values are adjusted by equal weight group observation. 6.4.4 Supplementary measurement of direction observation
When the number of directions is more than three, the direction that is not suitable for observation can be temporarily abandoned in a measurement round of direction observation. The number of abandoned directions shall not exceed one-third of the number of directions to be measured. The supplementary measurement of abandoned directions can only be combined with the zero direction. 6.4.5 Provisions on joint measurement
a) When setting up a station for observation for the second time at a point that has been observed, two known directions should be measured jointly; b) When setting up a station at a high point to measure low directions jointly, two high directions should generally be measured jointly. When the same person observes directions of different levels at a point, he can only measure one high direction that he has observed. c) When measuring two directions jointly, the limit of the difference between the new and old angle values converted to the same center is ±2Vm + m. In the formula: ml, m2 are the angle measurement mean errors specified for the corresponding new and old results levels. 6.5 Limits and re-measurements of horizontal angle observations
6.5.1 The observation limits of the full combination angle measurement method shall be implemented in accordance with Table 6. Table 6
Mutual difference of three readings of main telescope and deflection observation mirror eyepiece micrometerDifference of two overlapping readings of optical micrometer
Difference of angle values of upper and lower half measurement
Mutual difference of each measurement at the same angle
Mutual difference of direct and indirect angles
3~4 directions
5~6 directions
7 and more than 7 directions
Maximum closure difference of triangle
When the three-direction method is used for observation, the three-direction group implements the tolerances of Table 7, and the rest of the items are subject to the tolerance requirements of this table. 6.5.2 Tolerance of directional observation method
The tolerance of directional observation method shall be implemented in accordance with Table 7.
Difference of two coincident readings of optical micrometer
Regression zero difference of half measurement
--2C mutual difference within the measurement round
After returning to the same starting direction, the mutual difference of each measurement round of the same direction value
Maximum closure difference of blue angle
Remeasurement of over-limit observation value
a) All complete measurement rounds exceeding the limit error specified in Table 6 and Table 7 must be remeasured. 294
GB/T17942--2000
b) The number of remeasurements of the angle measurement method is calculated according to the number of basic measurement rounds to be remeasured. When the number of remeasurements exceeds 1/3 of the basic measurement rounds, all points should be re-observed.
c) The number of remeasurements of the square observation method is calculated according to the number of direction measurement rounds to be remeasured. The total number of direction measurement questions for each result is (n·1)mn is the number of directions and m is the number of measurement rounds. When the number of remeasured directions exceeds 1/3 of the total number of direction surveys, the point should be re-observed. d) When the mutual difference of the surveys exceeds the limit, except for obvious isolated values, the maximum and minimum values in the group of observations should generally be re-measured. e) In the direction observation method-in the survey, if the number of remeasured directions exceeds 1/3 and one of the observed directions needs to be re-measured, the entire survey should be re-measured. At this time, the number of remeasurements is calculated only according to the surveys of the directions that exceed the limit. If the whole survey is re-measured because the zero direction exceeds the limit, it is counted as (n·1) re-measured direction surveys. f) Direction observation re-measurement only requires the zero direction to be measured. g) The results of the basic surveys and re-measured surveys of the observations should be recorded in the book. Only one result that meets the limit difference is used for each survey (i.e. each degree disk position).
h) In the full combination angle measurement method, a single angle can be re-measured when the limit between the direct and indirect angles exceeds the limit. 6.6 Determination of centroid elements
Centroid elements include eccentricity: and eccentricity angle 6.6.1 Special symbols for determination of centroid elements
a) ey, eH, er represent the distance from the projection center of the instrument, light return, circle stick (or center column) to the projection center of the standard stone, which is called eccentricity, measured to millimeters:
b) 6,, 8H,. respectively represent the angle measured clockwise from the eccentricity direction to the zero direction line with the projection center of the instrument, light return, circle stick (or center column) as the vertex, which is called eccentricity angle, measured to 15°; c) When there are multiple instruments and light return centers at a point, the eccentricity and eccentricity angle of the projection point should be marked with subscripts such as 1, 2..., etc. For example, ey1, 8.1, and indicate the directions to be corrected respectively. 6.6.2 Methods and requirements for determining the centroid elements a) The determination of centroid elements is generally carried out by the graphical method. Using a theodolite, stations are set up in three directions of about 120° (60°) around the triangulation point. For example, the left and right positions of the station are used to aim at the center point to be projected as a vertical plane, and are recorded on the horizontal shadow paper respectively, and the projection points of each center are intersected. When the three projection lines of a certain center form an error triangle, the center of its inscribed circle is taken as the projection point. b) If there are terrain restrictions, stations can also be set up in two directions with an intersection angle of about 90°, and each station is projected twice continuously (the left and right positions of the instrument are slightly changed between the two times). When the projection lines form an error triangle, the intersection point of its diagonals is taken as the projection point. c) The longest side of the above-mentioned projection error triangle or the long diagonal of the error quadrilateral shall not be greater than 5mm for the projection of the standard stone, instrument, and return light center, and shall not be greater than 10mm for the projection of the circle and the center column. d) Other rigorous methods can also be used to obtain the projection point according to actual conditions. When the projection paper is placed on the instrument table, the position of the instrument or the center of the return light on the projection paper can be determined by intersection and other methods. e) After the intersection of the projection centers on the projection paper is completed, two directions of observation of the local point should be drawn on each projection center except the center of the benchmark stone, and it is best to have one of them as the zero direction of observation. When determining the centering element of the sighting point at a triangulation point without station observation, two directions including the direction of the station must be drawn. If there is no direction value on the point, the angle between the drawn directions should also be observed and recorded on the projection paper to the nearest minute.
f) The difference between the angle between the two directions drawn by each projection center and the observed value should not exceed 2° when the eccentricity is less than 0.3m; when the eccentricity is greater than 0.3m, it should not exceed 1°
g) In the first and second order triangulation observation, the eccentricity of the station or sighting point should generally not exceed 0.5m, and the third and fourth order triangulation observation can be appropriately relaxed.
When the eccentricity is too large and the centering element cannot be determined by the graphical method, the eccentricity angle can be directly determined by the theodolite. The eccentricity (horizontal distance) can be measured twice by analytical method or direct text. The difference between the two times shall not exceed 10mm. 6.6.3 Requirements for the number and time of centering element determination a) When observing the first-order triangulation point, the centering element of the survey station should be determined once before and after the observation. The sighting point and centering element only require pre-measurement and post-measurement control. The time interval between the above two centering element determinations shall not exceed two months, otherwise the number of determinations shall be increased. 295
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