Where Theory Meets Practice Archives
Error Ellipses
Part 2: Components and Increasing Probability In the previous article (April 2017) I discuss the correlation of the coordinate values for a station and how an error ellipse is used to determine the direction of the largest error at a station. In this article I review the components of an error ellipse, the process that […]
Where Theory Meets Practice: United States Standard Datum
This month we provide the history behind the theory and practice usually presented here by Dr. Charles Ghilani. This is an explanation of the first national horizontal datum used by the NGS (back then called the U.S. Coast and Geodetic Survey) in the late 1800s. In the 1970s when NGS created its database, the data developed on […]
Single Transformation with ECEF
We at xyHt think this topic is one surveyors should be talking about. Instead of placing this reader’s letter to us as a comment under Dr. Ghilani’s article (linked below), we are making it a post itself to encourage discussion underneath. Editor Gavin Schrock, PLS, started us off, below. Professor Ghiliani’s article, Transformation of Observations […]
Guest Essay: Change is Hard, But It’s Not the End
Chances are that students currently enrolled in surveying and geomatics programs are familiar with the writings of Dr. Charles Ghilani, author of such reference/textbooks as Adjustment Computations: Spatial Data Analysis and Elementary Surveying (An Introduction in Geomatics). Dr. Ghilani is a professor of engineering in the Surveying Engineering Program at Pennsylvania State University. He received his PhD […]