SURV1200 Lecture Notes - Lecture 6: 3D Systems, Arc Length, Spherical Earth
2 Jun 2018
School
Department
Course
Professor
SURV 1200
Introduction into Surveying
6.Coordinates and Datums
A National Datum – A National coordinate system is used to integrate all engineering work
mapping, geographic information and land management.
All major infrastructure projects reply on spatial data sets for planning, setting out and
construction as building and ongoing monitoring and maintenance
Coordinates
1. Local Datum – used from small local projects
2. National Datum – All countries have their own national datum to interrelate nationally
important information
3. Global Datum – Has been evolving since the use of satellite, and the future direction for
Datum
Either no Datum or a Local Datum means that other surveys will not be able to link into the
coordinate system
Where a National Datum and Global Datum can interrelate within each other ensuring
different surveys can be connected and linked into the same coordinate system.
Local Datum
No need to connect to other coordinate system used form large industrial sites, domestic
dwelling construction, local detail survey. Uses TBM – Temporary Bench Marks
Pros- Values on the plan can be measured on the field, these values are small in magnitude and
thus manageable – Low cost – Pane surveying (E, N, Ht) uses simple trig
Cons- No connection to other datums, may not be reproducible if the definition of the grid is
destroyed since TBM’s are used.
National Datum
To provide access to the national wide coordinate system, state and federal government
authorities to provide a network of control points like boundaries an lots.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
A national datum a national coordinate system is used to integrate all engineering work mapping, geographic information and land management. All major infrastructure projects reply on spatial data sets for planning, setting out and construction as building and ongoing monitoring and maintenance. Either no datum or a local datum means that other surveys will not be able to link into the coordinate system. Where a national datum and global datum can interrelate within each other ensuring different surveys can be connected and linked into the same coordinate system. No need to connect to other coordinate system used form large industrial sites, domestic dwelling construction, local detail survey. Pros- values on the plan can be measured on the field, these values are small in magnitude and thus manageable low cost pane surveying (e, n, ht) uses simple trig. Cons- no connection to other datums, may not be reproducible if the definition of the grid is destroyed since tbm"s are used.
