Abstract: The non-prism measurement technology in the Feng-Yun application of highway cross-section measurements on the efficiency of non-prism measurement accuracy and the applicable conditions and results analysis.
Key words: non-prism measurement techniques; cross-section measurement; accuracy analysis

1 Project Overview
     The engineering survey mission is to Feng Yun highway topographic mapping, and for the design of flat band topographic maps, as well as vertical and horizontal cross-section.

2 Optimization of the working methods of vertical and horizontal cross-section measurement of
Highway tunnel cross-section survey work is in the field along the channel central axis with the tape Measure the channel mileage, from 0 +000 Stake started every 10-meter mark on a cross-section of Stake, there are important channels for water facilities, or terrain changes in the subsidiary a larger increase in cross-section of local Stake. With the water level measured from the first-stage control point elevation to the sections cited in the pile, thereby finishing the pile mileage and elevation mapping will be entitled to channel vertical section diagram. And then cross-sectional measurements, usually there are two ways to cross-sectional measurements, the first one is the field measurement method, the pile began to cross-section from both sides of the vertical ruler with two intersecting lines of planning based on expenditure to the various points of spacing and elevation difference, collate the data plotted cross-section, this approach requires testing facilities must reach the cross-section on each feature point. Feng-Yun Highway region due to the complex geological conditions, landslides have occurred, the steep slope of the mountain sides and there is no rule, measure each section will have to pay a high price, simply using this method will waste a lot of manpower and material resources; second measurement methods in the field with total station measurements, easy-to-walk in the flat areas based on field measurement method, used elsewhere in Total Station measurements, the advantage of saving time and resources to solve the high slope on the facilities staff can not be measured measuring cross-section, we opted for this method. Feng Yun found in the work of some parts of the expressway, such as the Feng-Yun highways are rocky mountain high slope slope, slope over 60 degrees and no change in the law, subject to conditions, Shi test it difficult to reach the middle slope characteristics of point, point taken, if a simple point and top of the hill slope with the slope-point connected to draw the cross-section does not match with the field, resulting in the amount of engineering and engineering estimates accuracy unreasonable deviation. To solve this problem, we have adopted a non-prism Total Station Leica TPS1200 measurements.

About three non-prism measurement techniques and their application conditions
3.1 Non-prism measurement Introduction
   Non-prism measurement technology is based on principles of phase-based method, issued a very narrow laser beam, can be very accurately hit the target to ensure high-precision distance measurement. Measurements are compared with the prism, its advantage is that as long as the measuring point of the reflective medium in line with non-prism measurement conditions, do not need to be placed at the measuring point on the prism, you can measure the three-dimensional coordinates of the point. Within the scope of this technology around the world has been widely used, it has good technical specifications: high-precision (3mm + 2ppm), large-scale (using the standard Kodak gray cards, which range up to 180 meters [1]), with a visible red laser spot, as well as a small beam diameter. In order to achieve excellent standards, using 3R-level visible laser, and using non-prism distance measuring technology phase-based method. As for the International Laser standards, 3R laser class is relatively is relatively new, it is often a class 3B laser mix to use. Class 3R laser laser is a relatively new standard, its safety classes ranging from two lasers and laser class 3B between the guide contains fewer security restrictions. From this perspective, 'R' is used to indicate "requirements to simplify." Class 3R laser non-reflecting prisms ranging in their application can be measured in scope than the Class 2 laser with a fold increase for the surveyors to improve operational efficiency is beneficial. In accordance with international laser safety standards, 3R type laser operators should be careful not to make people look directly at a laser beam eyes. To trigger a measurement when the measurement of key personnel, the laser can be activated to measure completed its been closed. When you open a laser pointer, when, 3R type lasers can also be activated. The human eye exposed to laser lines such as, naturally, some of the reactions (for example: pupil narrowing, strabismus, eye transfer) will be more or less harm reduction, so that the human eye in the laser beam because of the more unintentionally a long time the possibility of injury caused negligible in.
3.2 Non-prism measurement conditions for the application
     Each measurement has its own characteristics and scope of practice found in non-prism measurement techniques applicable to the following conditions:
     (1) applies to pass, as the conditions are good, reflecting the media's good points, in the reflective medium dark, smoking was too light, reflected poor conditions in places like inappropriate use of non-prism measurements.
(2) Non-prism measurement technique suitable for measurement of reflective surfaces exposed to the measuring point elevation, such as rocks, housing, roads, etc., and within sight of the topography, surface features point of elevation.
(3) non-prism measurement for line of sight no obstacle to measuring the topography of surface features, if there are any obstacles between the measured coordinates of the obstacles, elevation. To measure the terrain outside the 400-meter point, if there is a place in the 200 meters line of sight leaves block will be measured is the foliage of the coordinates, elevation.
(4) non-prism measurement consumes a larger power supply, outside the industry will be ready to meet the power, if necessary, equipped with an external power supply.
(5) Be careful not to mirror the surface like a laser beam fired.
(6) Shi measured during the process of observing a long time through the eyepiece the subject matter in order to avoid the eye a long time where the laser beam caused injuries.
(7) applies to non-prism measuring it difficult to reach, reflecting the media a good terrain measurement, such as cliffs, valleys, traffic major highway, there are highly toxic and other surface features.

4 Leica TPS1200 characteristics and Shi testing process
4.1 TPS1200 features
     Leica TPS1200 is a long measuring range, ultra-high precision with a variety of functions and easy to use total stations. Intuitive menu-based operating system, clear, able to guide users to complete the work required independently, users can set up their own operations as needed, display and output. TPS1200 offers many on-board programs, such as measurement, set up stations, lofting, coordinate geometry, you can use G eoC + + procedures for the preparation of a dedicated airborne. Coaxial measuring principle is the visible red laser phase measurement, non-prism measurement range of 500m, while measuring accuracy 2mm +2 ppm / typ, angle measuring accuracy of 2 〃.
4.2 Shi test process
4.2.1 Control Survey
    Highway tunnel project a very high elevation accuracy requirements, due to channel length, the error accumulation of more error is too large will affect the accuracy of wire. Therefore, we use the Pentax and SOKKIA LEVEL simultaneous operation of two operating groups, the first-stage elevation control points from the GPS measurement cited to various sections, the elevation difference closure are to meet the specifications. In the section line pass as the selected conditions are good, easy to set up stations where prism tripod to do with the TPS1200, and wires, encryption map the root points to the cross-section.
4.2.2 Cross-section Measurement
     (1) equipment set up
     The root point of the encryption map set up equipment, leveling pair. And then enter the station set, such as station coordinates, orientation and so on, according to the following steps:
     ① start the program interface, press F3 (station);
     ② Move the cursor to a known point of operation, with the navigation button to select a known point where the operation;
     ③ Move the cursor down the directional method, the navigation keys to choose the orientation approach;
     ④ Press F1 (continue) to enter the next window. Select test site, the point number;
     ⑤ Enter number after the point of view. At this point instrument will show a negative attitude azimuth, press F2 (ranging), we can see azimuth difference, flat and the elevation difference from the poor poor, used to evaluate the quality orientation.
     (2) Create a line, follow these steps:
     ① activate the main menu management / data, according to F6 (FF) will show the window switch to the line;
     ② F2 (New) Create a line;
     ③ Line No.: Enter the line name, storage point: choose to use the point, linear: Select linear;
     ④ F1 (save) storage. F6 to activate the input coded information.
    (3) cross-section line measurement
     Activated to measure the line, in the measurement window in order detailed measurement of the line, the measuring point automatically relegated to activate the line. Set the instrument EDM types, its meaning is as follows:
     EDM type: Prism (IR), the use of infrared light with the prism rangefinder.
               RL (RL), use visible red laser for non-prism distance measurement.
               Long-distance (LO), Long Distance measuring range.
     Under normal circumstances, the EDM type setting in the prism (IR) state, with the prism with the Total Station field data collection, and so can more accurately capture the cross-section of feature points. In the non-prism measurement can be, and there is no obstructions blocking line of sight, reflection, and media people are able to reach a better place, put the DEM type is set to the RL state, that is, non-prism measurement of the state, EDM mode is set to standard mode. Target under test feature, according to the measurement of key, instruments began to measure, two seconds later you can measure the coordinates of the point. So repeated measurements, until satisfied with the non-prism measurement conditions, then EDM type set to IR state to continue to measure. In the measuring process, press F6 (FF), switch to the graphics window. In this window can also be nearly F1 (measuring deposit), F2 (ranging), F3 (records), at the same time to see the measured points marked on the map. If it strays somewhat from the cross-section line, the amendment to the section immediately online. Measurement of End or the disconnection measurements, shut down the line.

4.2.3 Cross-sectional Digital Mapping
After the raw data collected by the South CASS5.0 software data to a computer, the show points into the map, calculate the amount of points accumulated distance and elevation, finishing as a "tired, distance / elevation" type *. hdm files, import Southern CASS5.0 mapping software, with the mileage generated graphics, such as section 7 +040 cross-sections:

Cross-sectional diagram 7 +040
5 short-range non-prism measurement of the gross error detection
Because there was no prism measurement technology as the mapping industry, a new technology in production, its accuracy is that people are most concerned about how the problem, for which we have broad vision, reflecting a better place in the media (IR) status with the infrared light with the Prism range and RL status (non-prism measurement) two sets of data collected. As measured by the distance no farther than 300 meters away from the weather oblique corrections, plus by constant correction, tilt correction, projection corrections are very small [2], its impact is negligible. The flat directly from the data collected, such as data comparison table:
Data Comparison
Point No. 12345
There prism-ping distance Di (m) 61.8263 63.4721 67.7310 69.3298 88.0427
No prism flat from Dr (m) 61.8265 63.4720 67.7312 69.3297 88.0428
△ D +0.0002 -0.0001 +0.0002 -0.0001 +0.0001
     Above table can be seen, TPS1200 a flat prism distance measurement and non-prism distance measuring basically the same level, △ D up to 0.2mm, the relative accuracy of 3.2 × 10-6, the gross error is very small, to meet the measurement accuracy requirements .

6 Summary
6.1 Non-prism Total Station measurement technology advantages
     Feng-Yun highway through Ordnance Survey, the cross section measurement engineering practice, understand the non-prism measurement techniques applied in the mapping industry, liberating the productive forces, and enhance efficiency. According to conventional mapping methods, infrared light with the prism measurement, under normal circumstances, with an average day, the measured cross-section of 1.4km. If the same project simultaneously using non-prism measurement techniques and prism measurement techniques, as long as the reflection of the local media does not meet the conditions to implement a prism measurement, who meets the non-prism measurement conditions of the place, can be measured directly without measuring staff Shi feature points placed to reach the prism, considerable savings in manpower and material resources under the same conditions, with an average day, 1.8km cross-section measurements, the working efficiency nearly 30%, saving time and speed up the progress of foreign trade, improve efficiency and reduce the measurement of the labor intensity, can quickly and accurately to relevant departments to provide measured results of [3], for the latter part of the professional design work started to create the conditions for the advance.
     In summary, non-prism measurement technique main advantages:
     (1) no-prism measurement will be applied to measure it difficult to reach the feature points, such as steep cliffs, there are highly toxic chemical area, high temperature and pressure areas and so on.
     (2) rapid, accurate, saving manpower and resources, saving time.
     (3) applies to the city a better reflection dielectric measurements, cadastral mapping, and even single-person measurements.
     (4) can be accurately mapping the borders of certain restricted or closed area a limited range of terrain and will help to provide engineering planning area complete topographic information, eliminating the need for routine work needed to enter these restricted areas related to social work coordination matters.
6.2 recommended
    Non-prism measurement techniques Although there are a wide range of superior performance and advanced features, but not a panacea, especially for field observations of a variety of conditions, equipment can not change it, can not fully adapt. Therefore, operating personnel should fully understand the characteristics of this new technology to take the necessary measures to avoid weaknesses, in order to give better play to the advantages of advanced technology and equipment to obtain a good observation results. Our side to use, while groping in the process that has the following suggestions worth exploring:
(1) against non-prism measurement restricted by the barrier, making it easy Shi measurement error on the subject matter, it is recommended on the device non-prism distance measurement range of additional features, make full use of operating staff mesh estimated capacity. To measure 400 meters of the subject matter, set ranging range 350-420 m, they will not mistakenly measuring 200 meters of heading material.
(2) To avoid the eyes by laser injury, proposed the creation of a high-powered visible light targeting system.

     References:

    [1] IEC 60821-1. The safety of laser products: Part One. Equipment classification, requirements and user guide. (IEC 60825-1 revision A2), [S]