Base 9 Geodetic Consulting Services

If you can’t answer these questions:

• As part of the North American tectonic plate, how fast and in what direction per year is your state moving?

• What is the default coordinate system used by GPS?

• What U.S. federal agency is responsible for the definition and maintenance of WGS 84?

You might want to take the Practical Geodesy for Practical Surveyors!

 

If you can’t answer these questions:

• What, if any, are the most significant problems with both NAD 83 and NAVD 88?

• What is the approximate positional difference between NAD 83 and the ITRF?

• What the biggest problem that keeps leveled height differences from being the same as those derived strictly by gravity observations.

• Why do surveyors need to understand the “epoch” of coordinates and heights?

You might want to take the Rationale For and Expectations of the Planned Geodetic Datum Changes!

 

If you can’t answer these questions:

• Why are NAD 27 and NAD 83 different? NGVD 29 and NAVD 88?

• What transformation tools are available to go between them, and how do I use them?

• What is the best transformation tool to go between WGS 84/ITRF and NAD 83?

You might want to take the Datum Transformations Seminar!

 

If you can’t answer these questions:

• What is the typical size in miles of a single State Plane Coordinate Zone, and why are they that size?

• When computing State Plane Coordinates, what is the difference between the NAD 83 Elevation Factor and the NAD 27 Sea Level Reduction Factor?

• Which foot conversion (International or U.S. Survey) does your state use in the definition of State Plane Coordinates?

You might want to take the U.S. State Plane Coordinate System Seminar!

 

If you can’t answer these questions:

• Can GNSS be employed to produce Second-Order Class II heights?

• Where can you find information on the estimated accuracy of a geoid height from the most current NGS geoid model?

• What are the two fundamental positional elements that combine to produce a GNSS-Derived orthometric height?

You might want to take the GNSS-Derived Heights Seminar!

 

If you can’t answer these questions:

• How does NGS create the geoid model and how good is it in my state?

• Where does the data on NGS passive control data sheets come from and how is it kept reliable and up to date?

• What kinds of information can I submit to update passive control and what tools are available to do this.

You might want to take the seminar on How You Can Invest in Improving the Status of Passive Control!