Electronic Distance Measurement

1990 ◽  
Author(s):  
J. M. Rüeger
Keyword(s):  
Distance Measurement ◽  
Electronic Distance Measurement

Calibration baselines in canada

CISM journal ◽  
1988 ◽  
Vol 42 (3) ◽  
pp. 207-215
Author(s):  
D. Gillis ◽  
L. Nabe
Keyword(s):  
Geodetic Survey ◽  
Distance Measurement ◽  
Joint Program ◽  
Length Standard ◽  
Electronic Distance Measurement

The establishing, measuring and monitoring of Electronic Distance Measurement (EDM) cali¬bration baselines in Canada is a joint program of the Geodetic Survey of Canada and provincial, territorial and municipal surveying agencies. Since its establishment in 1971, the 2.3 km National Geodetic Baseline (NGBL) in Ottawa has been used as the reference baseline for other calibration baselines; two precise EDM instruments, the Mekometer ME3000 and the Geomensor CR204, have been used to transfer the length standard of the NGBL to baselines across Cana¬da. Thirty-six calibration baselines, established as part of the National Baseline Program, now exist. The Geodetic Survey strives to maintain the published values of interpier distances at the highest accuracy possible. To this end, extensive remeasurements are being planned. For longer distances which may be required to calibrate or check GPS instruments, a calibration network with lines up to 222 km is being established.

Recent work at NML to establish traceability for survey electronic distance measurement (EDM)

2003 ◽  
Author(s):  
Nicholas Brown ◽  
Rob Veugen ◽  
Gert-Jan van der Beek ◽  
Ronald F. H. Hugers
Keyword(s):  
Recent Work ◽  
Distance Measurement ◽  
Electronic Distance Measurement

Using portable laser EDM for forest traverse surveys

1995 ◽  
Vol 25 (5) ◽  
pp. 753-766 ◽  
Author(s):  
C.J. Liu
Keyword(s):  
Adverse Effects ◽  
Field Measurement ◽  
Experimental Tests ◽  
Cost Effective ◽  
Distance Measurement ◽  
Forest Stand ◽  
Forest Stands ◽  
Laser Technology ◽  
Electronic Distance Measurement ◽  
Area Determination

A new electronic distance measurement (EDM) device that utilizes laser technology for tree measurement and surveying was used to study traverse surveys of forest stands. Experimental tests demonstrated that the laser EDM device afforded (1) an allowable angular closure error of 3°, (2) an average linear closure precision of 1/550 for a bidirectional traverse and of 1/470 for a unidirectional traverse, (3) an average traversing speed of 0.25 mi/h (0.40 km/h) for bidirectional traverses, and (4) an average surveying rate of 6 acres/h (2.4 ha/h). The study also showed that (1) the digital laser EDM device was 10 times more cost effective than the traditional analogous surveying equipment and (2) a unidirectional traverse is, on the average, 1.5 times more effective than a bidirectional traverse. Additional analyses revealed that the interior angle adjustment (IAA) procedure consistently altered the shape of the stand and changed the stand area. These findings led to several suggestions: (1) the laser EDM device should be adopted for forest stand traverse surveys because it is easy to use, accurate, and cost effective; (2) the routine of taking backsight in field measurement provides little gain in accuracy in stand area determination and should be exercised only when local magnetic interference is expected to adversely affect compass accuracy; and (3) the conventional practice of IAA prior to balancing the traverse should not be exercised, since this procedure has adverse effects on mapping and area determination.

SURVEYORS’ GUIDE TO ELECTRONIC DISTANCE MEASUREMENT

Survey Review ◽  
1968 ◽  
Vol 19 (147) ◽  
pp. 238-239
Author(s):  
A. G. Dalgleish ◽  
M. J. Clegg
Keyword(s):  
Distance Measurement ◽  
Electronic Distance Measurement

scholarly journals Influence of surface reflectivity on reflectorless electronic distance measurement and terrestrial laser scanning

2014 ◽  
Vol 8 (4) ◽  
Author(s):  
Miriam Zámečníková ◽  
Andreas Wieser ◽  
Helmut Woschitz ◽  
Camillo Ressl
Keyword(s):  
High Precision ◽  
Laser Scanning ◽  
Laser Scanner ◽  
Signal Strength ◽  
Distance Measurement ◽  
Measured Signal ◽  
Systematic Effect ◽  
Surface Reflectivity ◽  
The Impact ◽  
Electronic Distance Measurement

AbstractThe uncertainty of electronic distance measurement to surfaces rather than to dedicated precisionre flectors (reflectorless EDM) is afected by the entire system comprising instrument, atmosphere and surface. The impact of the latter is significant for applications like geodetic monitoring, high-precision surface modelling or laser scanner self-calibration. Nevertheless, it has not yet received sufficient attention and is not well understood. We have carried out an experimental investigation of the impact of surface reflectivity on the distance measurements of a terrestrial laser scanner. The investigation helps to clarify (i)whether variations of reflectivity cause systematic deviations of reflectorless EDM, and (ii) if so, whether it is possible and worth modelling these deviations. The results show that differences in reflectivity may actually cause systematic deviations of a few mm with diffusely re- flecting surfaces and even more with directionally reflecting ones. Using abivariate quadratic polynomial we were able to approximate these deviations as a function of measured distance and measured signal strength alone. Using this approximation to predict corrections, the deviations of the measurements could be reduced by about 70% in our experiment.We conclude that there is a systematic effect of surface reflectivity (or equivalently received signal strength) on the distance measurement and that it is possible to model and predict this effect. Integration into laser scanner calibration models may be beneficial for high precision applications. The results may apply to a broad range of instruments, not only to the specific laser scanner used herein.

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