Conservatoire national des arts et métiers (Cnam), European Organization for Nuclear Research (CERN), and School of Management and Engineering Vaud (HEIG-VD) are three institutions that have developed their own network adjustment applications: Compensation de Mesures Topographiques (CoMeT), Logiciel Général de Compensation (LGC), and Trinet+, respectively.

In all these applications, three-dimensional mathematical functional models are used to process observations. However, some discrepancies may exist in the obtained results between these applications due to differences in the implementation of the functional models.

Since 2017, we are working together to study the compatibility and the interoperability between our network adjustment tools. In 2020, a common research paper was published in the Journal of Surveying Engineering:

Durand Stéphane, Touzé Thomas, Jones Mark, Guillaume Sébastien, Cattin Paul-Henri, Morel Laurent
Evaluation of Compatibility among Network Adjustment Software: CoMeT, LGC, and Trinet+
Journal of Surveying Engineering
Volume 146 - Issue 2 - May 2020

We are also working in order to include other commercial or free network adjustement applications in our tests.

This page contains some informations about this work, which is still in progress.

Network design

Warning (figure 1 in the 2020 article): In the paper publised in 2020 in the Journal of Surveying Engineering, point P1 and P2 have to be permuted to correctly use the datasets proposed on this webpage. The figure located on this webpage is the correct one (P1=A, P2=B).

Warning (DMS value for latitude of point P0): In the paper publised in 2020 in the Journal of Surveying Engineering, the correct DMS value for the latitude of point P0 is 46°13′56.21′′ N.

The principal point P0 at CERN is the barycentre of all our test networks.

Geodetic latitude and longitude for point P0 are 51.3692 and 6.72124 grads with respect to the CERN Geodetic Reference Frame (CGRF) (the reference frame tied to the reference IAG GRS 80 ellipsoid). For P0, the ellipsoidal height is defined to be 433.65921 m and the geoidal undulation is zero.

In order to generate coordinates for our test networks, we defined a P0 point which have the same definition in ERTF89 than the CERN P0 point in the CGRF: same values for latitude, longitude and elipsoidal height with no geoidal undulation with respect to IAG GRS 80 ellipsoid. The following table summarizes the ETRF89 coordinates of this P0 point:

Ellipsoidal coordinates (wrt. IAG GRS80)Cartesian coordinates
Latitude51.3692 grads46°13′56.21′′ NX4395400.3638 m
Longitude6.72124 grads006°02′56.82′′ EY465785.0567 m
Ellipsoidal height433.65921 mZ4583458.2260 m

Given a side length d, north and east coordinates for the points A, B, and M are computed in the local astronomical system of point P0, point M being located north of point P0. These local coordinates are used to calculate ETRS89 geodetic Cartesian coordinates for all points in the test networks.

The CoMeT application is used to generate measurements in all the test networks. A Gaussian error is added to the computed theoretical observation values, in a particular way explained in an article (in french) of the revue XYZ (XYZ n°158 - 2018).

The main parameters used for the generation and the processing of the measurements are:

Refraction coefficient none
Standard deviation (angle measurements)0.3 mgrad
Standard deviation (slope distance)5 mm

Coordinates and measurements datasets

Point coordinates (ETRS89 geodetic Cartesian coordinates) and generated observations between points for each network side length are available:

Evaluated network adjustment tools

Interactive access to the results

An interactive tool showing the main results: estimated variance factor, 2D horizontal distance between estimated and theoretical coordinates and coordinate difference in the vertical component

Software: CoMeT [-•-] LGC [-▼-] Trinet+ [-◆-] Geolab [-▲-]
Columbus [-■-] Comp3D [-🞶-] MOVE3 [-⧗-] Star*Net [-✗-]
JAG3D (ELIP) [-⋈-] JAG3D (SPHE) [-⋈-]

Data type: Estimated variance factor 2D horizontal differences Vertical differences

Data Y limits: from to