Perform and explain geodetic computations



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Perform and explain geodetic computations


Level

6

Credits

5


Purpose This unit standard is for people who are working, or who intend to work, in the surveying profession in a geodetic context.
People credited with this unit standard are able to: perform and explain a manual adjustment of a three dimensional control traverse using conventional terrestrial observations; explain eccentricity corrections and perform manual eccentricity calculations; reduce and explain vertical angle observations; and explain and perform coordinate transformations.



Subfield

Surveying

Domain

Geodetic Surveying

Status

Registered

Status date

12 February 2010

Date version published

12 February 2010

Planned review date

31 December 2012

Entry information

Open.

Replacement information

This unit standard replaced unit standard 11132.

Accreditation

Evaluation of documentation and visit by NZQA and industry.

Standard setting body (SSB)

Infrastructure ITO

Accreditation and Moderation Action Plan (AMAP) reference

0101

This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Special notes
1 It is recommended that prior to assessment against this unit standard candidates are able to perform calculations for general surveying purposes. This may be evidenced by achievement of credit for unit standard 8800 and unit standard 8801.
2 The recommended reference for this unit standard is Denys, P. H. Geodesy and GPS – Survey Methods (Dunedin: School of Surveying, University of Otago) available from the publisher, email surveying@otago.ac.nz or telephone 03 479 7585. As this text is frequently updated candidates are advised to check with the publisher for the latest edition available.
3 For current information on datums and projections refer to the LINZ standards, guidelines and fact sheets available at http://www.linz.govt.nz/geodetic/standards-publications/standards/index.aspx such as:

LINZS25000 Standard for the New Zealand Geodetic Datum 2000;

LINZS25002 Standard for New Zealand Geodetic Datum 2000 Projections.
4 For performance criterion 4.2, geodetic software programmes are available from the LINZ website at http://www.linz.govt.nz/geodetic/software-downloads/index.aspx.
5 For assessment against element 3 zenith distance may be used in place of vertical angle observation.
Elements and performance criteria
Element 1
Perform and explain a manual adjustment of a three dimensional control traverse using conventional terrestrial observations.
Performance criteria
1.1 Terrestrial observations are reduced and final coordinates computed for a three dimensional control traverse accurate to two decimal places.
Range closed bearings, averaged and closed forward and back height differences, distances reduced using reduced heights, derived final coordinates.
1.2 Explanation determines why reduced heights are used to reduce measured distances to horizontal distances in relation to a three dimensional control traverse.
1.3 Methods of performing a control traverse adjustment are compared in terms of geodetic application.
Range bowditch, least squares.
Element 2
Explain eccentricity corrections and perform manual eccentricity calculations.
Performance criteria
2.1 Eccentricity corrections are explained in terms of purpose and use.
2.2 The effects of eccentricity at the instrument station are corrected on an observed direction and distance to maintain overall measurement accuracy in accordance with trigonometric formulae.
Range accuracy of – distance, bearing;

two calculations – one where the included angle between the target station and the main station is less than 180 degrees and one where it is greater.


2.3 The effects of eccentricity at the target are corrected on an observed direction and distance to maintain the geodetic accuracy of observations using trigonometric functions.
Range accuracy of – distance, bearing;

two calculations – one where the included angle between the target station and the main station is less than and 180 degrees and one where it is greater.


Element 3
Reduce and explain vertical angle observations.
Performance criteria
3.1 Corrections are applied to reciprocal vertical angles to determine height differences between two points accurate to at least two decimal places.
Range corrections – curvature and refraction, target heights, instrument heights, reciprocal vertical angle observations.
3.2 Reciprocal and one way vertical angle observations are explained in terms of their comparative advantages.
Element 4
Explain and perform coordinate transformations.
Performance criteria
4.1 Transformations are explained in terms of differences between GPS coordinates and datum and projections used in New Zealand.
Range differences between – geodetic datum, ellipsoid, and projection; grid coordinates and geodetic coordinates.
4.2 Grid coordinates (N,E) are transformed to geodetic coordinates (,λ) and vice versa within specified parameters using a geodetic software programme.
Range any two local projections;

excludes manual calculations.


4.3 Reductions are applied to a GPS baseline to transform the topocentric baseline vector to the equivalent projection bearing and distance.
Range distance includes – correction for slope, correction to ellipsoidal surface, line scale factor correction;

bearing includes – convergence.


Please note
Providers must be accredited by NZQA, or an inter-institutional body with delegated authority for quality assurance, before they can report credits from assessment against unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be accredited by NZQA before they can register credits from assessment against unit standards.
Accredited providers and Industry Training Organisations assessing against unit standards must engage with the moderation system that applies to those standards.
Accreditation requirements and an outline of the moderation system that applies to this standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The AMAP also includes useful information about special requirements for organisations wishing to develop education and training programmes, such as minimum qualifications for tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact Infrastructure ITO askus@infratrain.co.nz if you wish to suggest changes to the content of this unit standard.

Ó New Zealand Qualifications Authority 2017


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