From Axis Ground Ops corner...
Making sure during the proposal and setup phases of a project that everyone is on the same page, not only with respect to what you are doing and delivering, but also deeper technical matters is critical to successful project execution.
Many end users, and in some cases providers, don’t have a keen grasp on the importance of making sure a project is oriented to the correct horizontal and vertical control datum’s before the data collection process is undertaken. While it is common to get a request for NAD 83 State plane Grid coordinates, many people do not realize the number of adjustments that are included in that seemingly simple requirement. The number of adjustments varies from state to state, and many times the dates of the adjustments do not correspond with what you may be used to in your normal area of practice. Additionally, the increasing prevalence of Real Time Networks or NGS’s OPUS service for GNSS positioning is revealing that many users do not understand how much variation exists in the different adjustments, or that NAD 83/CORS does not match NAD/2007.
On a similar note, vertical datum’s can be equally complicated, but this time not as an adjustment centric issue, but rather a geoid model complexity. Occupation of a known point with a GPS receiver, and collection of real time data using different base station control points and geoid models will show some surprising variation in not only horizontal positioning, but orthometric heights as well. It is not un-common to see a shift of over 0.1’ feet in elevation by just changing the geoid model in the receiver and collecting data new data from the same setup, in essentially the same window of time. While these concerns may seem like technical surveying jargon, we would simply point out that your error budget on a project is limited, and what is available should be spent wisely.
Eliminating survey related technical issues in the control phase of a project will serve to make it easier to deliver the accurate results you need, with less effort and cost later in the project.