1. Overview

Comp3D is a micro-geodesy compensation software that enables computation on a limited spread network (few kilometers) using a global 3D least-squares bundle adjustment on several topometric observation types.

The computation is done in a local 3D system based on an oblique stereographic projection with a spherical Earth model.

1.1. Features

• simple graphical user interface (see Graphical User Interface)

• html interactive report (see Computation Report)

• simple input text format (see Input Files)

• input/output in any projection (see Georeferenced Projection)

• topometric observations (see OBS File)

• subframes adjustment (see Cartesian Subframes and Polar Subframes)

• rotation axes determination (see Rotation Axes)

• vertical deflection (see Vertical Deflection)

• equality constraints (see Equality Constraints)

• GNSS baselines (see GNSS Baselines)

• error detection assistance (see Residual Repartition, Rank Deficiency)

• many statistical indicators (see Observations)

• internal constraints (see Internal Constraints)

• simulations (see Simulation)

• Sinex format export (see Export Sinex)

• coordinates constraints covariance matrix input (see COR Covariance Matrix File)

• relative precision export (see Export Relative Precision)

• pipeline integration, command line interface (see Automatization)

• and more

1.2. Example of Workflow

Input preparation:

1. Create observations OBS File from measurements

2. Set coordinates for some starting points in COR File

3. Create a Project

Computation:

1. Initialization of all parameters (see Parameters Initialization step)

2. Bundle adjustment on all observations (see Computation)

Error correction:

1. Study results (see Observations)

2. Isolate errors (see Deactivated Observations) and fix them

Output results:

1. Computation Report

2. Exports

All input data come from text files (see COR File and OBS File). Project configuration and results are stored in a json-like .comp file that can be displayed in html. Some simple output text files are also created, such as .new file (see Output Coordinates).

When analyzing the results, please keep in mind that the computation is global and tridimensional. Therefore, it is crucial to avoid all aberrant measurements which, even in small number and well localized, may greatly disturb the whole network.