Gemini  

Least-Squares Adjustment Software 

What is Gemini

Gemini Least-Squares Adjustment Software is a suite of libraries and programs for adjusting surveying and geodetic data and estimating coordinates, heights, and gravity among networks of points. It is an extension of software developed by Polaris Geospatial Services (PGS) for the US National Geodetic Survey (NGS). Gemini also allows the adjustment of calibration baseline data for establishing a new baseline or for determining instrument-reflector offset and scale factor using an existing calibration baseline. It also allows for estimating a vertical gravity gradient from relative gravity measurements made at different heights along the same plumb line.

Gemini was written in modern C++ language by a team of PGS geodesists and computer scientists that have expertise in least-squares adjustment theory and a combined decades of experience in scientific and commercial software development.

A free 60-day trial of Gemini is available to anyone open to providing feedback to PGS on their use of Gemini (download below). Contact PGS for more information or for Gemini licensing prices.

Gemini features 

  • Suitable for networks of all sizes, from small surveying networks to large national networks.  

  • Supports minimally and overly constrained adjustments, including free network adjustments. 

  • Supports 3D geodetic networks, leveling networks, gravity networks, calibration baselines, vertical gravity gradients. 

  • Allows constrained and unconstrained a priori coordinates to be specified in Earth Centered Earth Fixed Cartesian (ECEF), geodetic, or map projection (state plane or UTM) coordinate systems.

  • Performs 3D network adjustments in 3D geodetic space for the utmost in modeling accuracy, outputting estimated coordinates in ECEF Cartesian, geodetic, and map projection (state plane or UTM) coordinate systems. 

  • Provides easy to create and read data formats; also supports NGS bluebook data format. 

  • Provides many computational options through a settings file, including: 

  • Blunder checks 

  • Loop closure checks 

  • Outlier detection 

  • Hypothesis testing on constraints 

  • Variance component estimation  

  • Supports units of meters and feet. 

  • Supports specification of centering errors at instrument and target stations. 

  • Outputs a plethora of files showing adjustment results, including: 

  • Text files 

  • CSV files that can be viewed in spreadsheets 

  • KML files for viewing network maps in Google Earth and GIS programs 

  • GMT script files for creating network maps and residual histograms using GMT (Generic Mapping Tools)   

  • Python and MATLAB scripts for observation and normal equations – useful for students and researchers 

  • Includes an extensive user’s manual that describes the software and explains the theory of least-squares adjustments and associated statistics.  

  • Runs on Windows and Linux computers. 

  • Gemini is currently a command-line interface (CLI) program without a graphical user interface.

Anticipated future features 

  • Network adjustments in local 2D and 3D coordinate systems. 

  • Pre-adjustment analysis of network precision. 

  • A basic graphical user interface. 

  • Least-squares adjustments involving 2D and 3D coordinate transformations. 

How to obtain Gemini for Windows 

  1. Download Gemini software files and order form below. 

  2. Unzip Gemini software and run ‘DevAct --device-id’ from a command line to obtain your device ID.

  3. Email completed order form and device ID to info@PolarisGeospatial.com.

  4. PGS will provide you a device activation key that allows you to run Gemini.