C. Kotsakis' homepage

Kotsakis C. (2016) Realization aspects of the International Height Reference System. IAG/IGFS International Symposium on Gravity, Geoid and Height Systems, Thessaloniki, Greece, September 19-24, 2016.  (full presentation)

Aslanidis N., Kotsakis C. (2016) Evaluation of NRTK-based heighting techniques from different operational GNSS networks in Greece. IAG/IGFS International Symposium on Gravity, Geoid and Height Systems, Thessaloniki, Greece, September 19-24, 2016.  (full presentation)

Kotsakis C., M. Chatzinikos (2016) Unconstrained NEQ with full rank in GNSS networks: crucial problem or trivial nuisance for TRF applications? Annual EUREF Symposium of the IAG Reference Frame Sub-Commission for Europe, San Sebastian, Spain, May 25-27, 2016.  (full presentation)

Kotsakis C., Chatzinikos M. (2015) Assessment of weighted and unweighted inner constraints on multi-session solutions for estimating station velocities in regional GNSS networks. IUGG 26th General Assembly, Prague, Czech Republic, June 22 - July 2, 2015.  (full presentation)

Chatzinikos M., Kotsakis C. (2015) Comparison of frame alignment strategies in GNSS coordinate time series. IUGG 26th General Assembly, Prague, Czech Republic, June 22 - July 2, 2015.  (full presentation)

Chatzinikos M., Stefanidou E., Kotsakis C. (2015) Spatial analysis of the interaction between a heterogeneous velocity field and a static GNSS-based reference frame: a Greek case study. IUGG 26th General Assembly, Prague, Czech Republic, June 22 - July 2, 2015.  (full presentation)

Aslanidis T., Iliadis K, Aslanidis N., Kotsakis C., Stefanidou E. (2014) Established use of geo-information systems in emergency pre-hospital medicine. 25th Medical Conference of the Hellenic Armed Forces, Thessaloniki, Greece, November 27-29, 2014.

Kotsakis C., Vatalis A., Sanso F. (2014) Helmert transformation and the intra-frame covariance effect in frame alignment problems. IAG International Symposium on Reference Frames for Applications in Geosciences, Kirchberg, Luxemburg, October 13-17, 2014.  (full presentation)

Chatzinikos M., Kotsakis C. (2014) Weighted vs. un-weighted MCs for the datum definition in regional networks. IAG International Symposium on Reference Frames for Applications in Geosciences, Kirchberg, Luxemburg, October 13-17, 2014.  (full presentation)

Kotsakis C. (2014) Design, realization and usage of a time-dependent high-accuracy geodetic reference frame for the Hellenic region (in Greek). Fourth Scientific Conference of the Hellenic Association of Rural and Surveying Engineers, Thessaloniki, Greece, September 26-28, 2014.  (full presentation)

Chatzinikos M., Kotsakis C. (2014) Quality assessment of the Hellenic Geodetic Reference System 1987 using a geodetic crustal velocity model for Greece (in Greek). Fourth Scientific Conference of the Hellenic Association of Rural and Surveying Engineers, Thessaloniki, Greece, September 26-28, 2014.  (full presentation)

Mikrou T., Ouzounoudis G., Kotsakis C. (2014) NETIST: A new software package for the adjustment and statistical analysis of geodetic and surveying networks (in Greek). Fourth Scientific Conference of the Hellenic Association of Rural and Surveying Engineers, Thessaloniki, Greece, September 26-28, 2014.  (full presentation)

Aslanidis N., Kotsakis C. (2014) Geo-referencing procedures for old land devision maps in the Hellenic Geodetic Reference System 1987 using GNSS observations: a case study in Dasochori, Serres (in Greek). Fourth Scientific Conference of the Hellenic Association of Rural and Surveying Engineers, Thessaloniki, Greece, September 26-28, 2014.  (full presentation)

Kotsakis C. (2014) Solving the reference station weighting problem in minimally constrained networks. Annual EUREF Symposium of the IAG Reference Frame Sub-Commission for Europe, Vilnius, Lithuania, June 4-6, 2014.  (full presentation)

Vatalis A., Kotsakis C., Sanso F. (2014) A rigorous approach for aligning regional GNSS networks to global reference frames based on the Helmert transformation. Annual EUREF Symposium of the IAG Reference Frame Sub-Commission for Europe, Vilnius, Lithuania, June 4-6, 2014.  (poster presentation)

Tsalis I., Amjadiparvar B., Kotsakis C., Sideris M.G. (2014) On the consistent combination of geometric and Helmert orthometric heights. Annual Scientific Meeting of the Canadian Geophysical Union, Banff, Canada, May 4-8, 2014.

Kotsakis C. (2013) Reference station weighting and frame optimality in minimally constrained networks. VIII Hotine-Marussi Symposium, Rome, Italy, June 17-21, 2013.  (full presentation)

Kotsakis C., Tsalis I. (2012) Improved formulae for consistent combination of geometric and orthometric heights and their associated velocities. IAG International Symposium on Gravity, Geoid and Height Systems, Venice, Italy, October 9-12, 2012.  (full presentation)

Grigoriadis V.N., Kotsakis C., Tziavos I.N., Vergos G.S. (2012) Estimation of the reference geopotential value for the local vertical datum of continental Greece using EGM08 and GPS/leveling data. IAG International Symposium on Gravity, Geoid and Height Systems, Venice, Italy, October 9-12, 2012.  (full presentation)

Vergos G.S., Grigoriadis V.N., Tziavos I.N., Kotsakis C. (2012) Evaluation of GOCE/GRACE global geopotential models over Greece with co-located GPS/leveling observations and local gravity data. IAG International Symposium on Gravity, Geoid and Height Systems, Venice, Italy, October 9-12, 2012.

Ampatzidis D., Kotsakis C., Katsambalos K. (2011) The need of a local reference frame in Greece: the deficiency of ETRS89 and a new proposed strategy. Annual EUREF Symposium of the IAG Reference Frame Sub-Commission for Europe, Chisinau, Moldavia, May 25-28, 2011.

Kotsakis C. (2010) The role of a conventional transformation model for vertical reference frames. IAG International Symposium on Reference Frames for Applications in Geosciences, Marne-La-Vallee, France, October 4-8, 2010.  (full presentation)

Ampatzidis D., Kotsakis C., Katsambalos K., Rossikopoulos D. (2010) Comparison of a geodetically-derived velocity field from the permanent NOANET-GPS network (2007-2010) with a microplate tectonic motion model over Greece. WEGENER 15th General Assembly, Istanbul, Turkey, September 14-17, 2010.

Kotsakis C. (2010) Do we need a conventional transformation model for vertical reference frames? Annual EUREF Symposium of the IAG Reference Frame Sub-Commission for Europe, Gavle, Sweeden, June 2-5, 2010.

Kotsakis C., Zoulida M., Terzopoulos D., Katsambalos K. (2010) Analysis of leveling heights over the trigonometric Hellenic geodetic network (in Greek). Third Scientific Conference of the Hellenic Association of Rural and Surveying Engineers, Athens, Greece, December 17-18, 2010.  (full presentation)

Ampatzidis D., Kalamakis N., Katsambalos K., Kotsakis K. (2010) Alternative methods for transforming land division maps of the Hellenic Ministry of Agricultute to the official Hellenic Geodetic Reference System 1987 (in Greek). Third Scientific Conference of the Hellenic Association of Rural and Surveying Engineers, Athens, Greece, December 17-18, 2010.

Gianniou M., Katsambalos K., Kotsakis C. (2009) Real-time positioning in ETRS89 using the Hellenic Positioning System. Annual EUREF Symposium of the IAG Reference Frame Sub-Commission for Europe, Florence, Italy, May 26-29, 2009.

Katsambalos K., Kotsakis C., Gianniou M. (2009) Hellenic Terrestrial Reference System 2007 (HTRS07): a regional realization of ETRS89 over Greece in support of HEPOS. Annual EUREF Symposium of the IAG Reference Frame Sub-Commission for Europe, Florence, Italy, May 26-29, 2009.

Kotsakis C. (2009) Heights and scale variation in their inherent reference frames. Annual EUREF Symposium of the IAG Reference Frame Sub-Commission for Europe, Florence, Italy, May 26-29, 2009.

Kotsakis C., Katsambalos K., Ampatzidis D., Gianniou M. (2008) Evaluation of EGM08 using GPS and levelling heights in Greece. IAG International Symposium on Gravity, Geoid and Earth Observation, Chania, Greece, June 23-27, 2008.  (full presentation)

Kotsakis C., Katsambalos K. (2008) The official transformation model between the reference system of HEPOS and the national Hellenic Geodetic Reference System of 1987. Scientific Symposium "HEPOS and modern geodetic reference systems: theory and practice, prospects and applications", School of Rural and Surveying Engineering, AUTH, Thessaloniki, Greece, September 25-26, 2008.

Katsambalos K., Kotsakis C. (2008) The geodetic reference system of HEPOS. Scientific Symposium "HEPOS and modern geodetic reference systems: theory and practice, prospects and applications", School of Rural and Surveying Engineering, AUTH, Thessaloniki, Greece, September 25-26, 2008.

Katsambalos K., Kotsakis C. (2008) Software modules for implementing the horizontal coordinate transformation between the reference system of HEPOS and the national Geodetic Reference System of 1987. Scientific Symposium "HEPOS and modern geodetic reference systems: theory and practice, prospects and applications", School of Rural and Surveying Engineering, AUTH, Thessaloniki, Greece, September 25-26, 2008.

Kotsakis C., Katsambalos K., Ampatzidis D. (2008) GPS-based levelling: current status and future prospects. Scientific Symposium "HEPOS and modern geodetic reference systems: theory and practice, prospects and applications", School of Rural and Surveying Engineering, AUTH, Thessaloniki, Greece, September 25-26, 2008.  (full presentation)

Katsambalos K., Kotsakis C., Vlachakis B., Ganilas A., Papoudas G. (2008) Time-dependent coordinate variations and velocity models. Scientific Symposium "HEPOS and modern geodetic reference systems: theory and practice, prospects and applications", School of Rural and Surveying Engineering, AUTH, Thessaloniki, Greece, September 25-26, 2008.

Huang J., Kotsakis C., Gruber T. (2007) Review of evaluation methods and test results for the quality assessment of Earth gravity models after the CHAMP and GRACE satellite missions. IUGG XXIV General Assembly, Perugia, Italy, July 2-13, 2007.

Kotsakis C. (2007) Reference frame consistency in CHAMP and GRACE earth gravity models. IUGG XXIV General Assembly, Perugia, Italy, July 2-13, 2007.

Kotsakis C. (2006) Correcting the smoothing effect of least-squares collocation with a covariance-adaptive optimal transformation. VI Hotine-Marussi Symposium on Theoretical and Computational Geodesy, Wuhan, China, May 29 - June 2, 2006.  (full presentation)

Kotsakis C., Katsambalos K. (2006) On the need for developing a modern 3D satellite-based geodetic reference system in Greece: problems, alternatives and applications (in Greek). Second Scientific Conference of the Hellenic Association of Rural and Surveying Engineers, Athens, Greece, December 8-9, 2006.

Kotsakis C. (2006) On the problem of geoid height transformation between different geodetic reference frames. First International Symposium of the International Gravity Field Service, Istanbul, Turkey, August 28 - September 1, 2006.

Dermanis A., Kotsakis C. (2005) Estimating crustal deformation parameters from geodetic data: Review of existing methodologies, open problems and new challenges. IAG International Symposium on Geodetic Deformation Monitoring: From Geophysical to Engineering Roles, Jaen, Spain, March 17-19, 2005.  (full presentation)

Kotsakis C., Ambatzidis D. (2005) Merging the geodetic networks of Greece and Egypt - An ambitious dream at the dawn of the 20th century (in Greek). Scientific Conference on the Development and Evolution of the Surveying Instruments, Methods and Measurement Systems of the Mapping Sciences in Greece, School of Rural and Surveying Engineering, AUTH, Thessaloniki, Greece, April 15-16, 2005.

Kotsakis C. (2005) The first aerial photogrammetric map of Athens (in Greek). Scientific Conference on the Development and Evolution of the Surveying Instruments, Methods and Measurement Systems of the Mapping Sciences in Greece, School of Rural and Surveying Engineering, AUTH, Thessaloniki, Greece, April 15-16, 2005.

Kotsakis C. (2004) Challenging the logic of least-squares methods for geodetic estimation problems. International Symposium on Modern Technologies, Education and Professional Practice in Geodesy and Related Fields, Sofia, Bulgaria, November 4-5, 2004.

Kotsakis C., Malmquist C. (2004) An evaluation of various digital elevation models over Canada. IAG International Symposium on Gravity, Geoid and Space Missions, Porto, Portugal, August 30 - September 3, 2004.

Kotsakis C. (2004) The effect of an unknown data bias on the statistical accuracy of least-squares solutions. IAG International Symposium on Gravity, Geoid and Space Missions, Porto, Portugal, August 30 - September 3, 2004.

Kotsakis C. (2004) A critique on the logic of the least-squares principle for the estimation of geodetic parameters. Joint Assembly of the American Geophysical Union and the Canadian Geophysical Union, Montreal, Canada, May 17-21, 2004.

Malmquist C., Kotsakis C., Sideris M.G. (2004) An assessment of digital terrain models over Canada. Joint Assembly of the American Geophysical Union and the Canadian Geophysical Union, Montreal, Canada, May 17-21, 2004.

Kotsakis C., Vella M.N.J.P. (2003) Improved fitting between gravimetric and GPS/levelling geoids using an extended similarity transformation model: a case study in Johor, Malaysia. IUGG XXIII General Assembly, Sapporo, Japan, June 30 - July 11, 2003.

Fotopoulos G., Kotsakis C., Sideris M.G. (2003) Estimation of variance components through a combined adjustment of GPS, geoid and levelling data. IUGG XXIII General Assembly, Sapporo, Japan, June 30 - July 11, 2003.

Kotsakis C., Tziavos I.N. (2003) Parametric versus non-parametric methods for optimal weighted averaging of noisy data sets. IUGG XXIII General Assembly, Sapporo, Japan, June 30 - July 11, 2003.

Kotsakis C. (2003) Weighted averaging of multiple data sets with no a-priori statistical information: some examples for noise reduction with simulated gravity anomaly data of varying accuracy. Annual Scientific Meeting of the Canadian Geophysical Union, Banff, Canada, May 10-14, 2003.

Fotopoulos G., Kotsakis C., Sideris M.G., El-Sheimy N. (2003) Development of a semi-automated approach for regional corrector surface modelling in GPS-levelling. Annual Scientific Meeting of the Canadian Geophysical Union, Banff, Canada, May 10-14, 2003.  (full presentation)

Kotsakis C. (2002) Improving the agreement between gravimetric and GPS/levelling geoids with a non-rigid similarity transformation model. Third Meeting of the International Gravity and Geoid Commission, Thessaloniki, Greece, August 26-30, 2002.

Bajracharya S., Kotsakis C., Sideris M.G. (2001) Aliasing effects in terrain correction computation using constant and lateral density variation. IAG Scientific Assembly, Budapest, Hungary, September 2-7, 2001.

Bajracharya S., Kotsakis C., Sideris M.G. (2001) Geoid determination using different gravity reduction techniques. IAG Scientific Assembly, Budapest, Hungary, September 2-7, 2001.

Fotopoulos G., Kotsakis C., Sideris M.G. (2001) Determination of the achievable accuracy of relative GPS/geoid levelling in northern Canada. IAG Scientific Assembly, Budapest, Hungary, September 2-7, 2001.

Kotsakis C., Fotopoulos G., Sideris M.G. (2001) A study on the effects of data accuracy and datum inconsistencies on relative GPS levelling. IAG International Symposium on Vertical Reference Systems, Cartagena, Colombia, February 20-23, 2001.

Kotsakis C., Sideris M.G. (2001) Non-stationary noise filtering of gravity data using fast spectral techniques. EGU XXVI General Assembly, Nice, France, April 26-30, 2001.

Kotsakis C., Fotopoulos G., Sideris M.G. (2001) Optimal fitting of gravimetric geoid undulations to GPS/levelling data using an extended similarity transformation model. Annual Scientific Meeting of the Canadian Geophysical Union, Ottawa, Canada, May 14-17, 2001.

Kotsakis C. (2001) Multiresolution spectral filtering of spatially-varying noise from gravity field data. Annual Scientific Meeting of the Canadian Geophysical Union, Ottawa, Canada, May 14-17, 2001.

Fotopoulos G., Kotsakis C., Sideris M.G. (2001) A simulative analysis for the achievable accuracy of relative GPS/geoid levelling in western Canada. Annual Conference of the GEOIDE Network of the Canadian Centres of Excellence, Fredericton, Canada, June 21-22, 2001.

Kotsakis C., Sideris M.G. (2001) Spectral filtering of spatially varying noise from digital geo-data. Annual Conference of the GEOIDE Network of the Canadian Centres of Excellence, Fredericton, Canada, June 21-22, 2001.

Kotsakis C., Sideris M.G. (2000) Aliasing error modelling in single-input single-output linear estimation systems. IAG International Symposium on Gravity, Geoid and Geodynamics, Banff, Canada, July 31 - August 4, 2000.

Fotopoulos G., Kotsakis C. (2000) Correlation and spectral analysis of distance-dependent DGPS errors over a network of reference stations. IAG International Symposium on Gravity, Geoid and Geodynamics, Banff, Canada, July 31 - August 4, 2000.

Kotsakis C., Bayoud F., Sideris M.G. (2000) Wiener filter modifications for gravity field data using different resolution levels and non-stationary noise. IAG International Symposium on Gravity, Geoid and Geodynamics, Banff, Canada, July 31 - August 4, 2000.

Kotsakis C., Sideris M.G. (1999) The high-frequency structure of the gravity field in Canada. Annual Scientific Meeting of the Canadian Geophysical Union, Banff, Canada, May 9-13, 1999.

Kotsakis C., Sideris M.G. (1999) Optimal combination of ellipsoidal, orthometric and geoidal heights for levelling purposes. Spring Meeting of the American Geophysical Union, Boston, Massachusetts, June 1-4, 1999.  (Invited)

Kotsakis C. (1999) Wavelets and Collocation: an interesting similarity. IUGG XXII General Assembly, Birmingham, U.K., July 18-30, 1999.

Kotsakis C., Sideris M.G. (1998) Study of the gravity field spectrum in Canada in view of cm-geoid determination. Second Joint Meeting of the International Gravity Commission and the International Geoid Commission, Trieste, Italy, September 7-12, 1998.

Fotopoulos G., Kotsakis C., Sideris M.G. (1998) Development and evaluation of a new Canadian geoid model. Second Joint Meeting of the International Gravity Commission and the International Geoid Commission, Trieste, Italy, September 7-12, 1998.

Kotsakis C., Sideris M.G. (1998) On the adjustment of combined GPS/Levelling/Geoid networks. IV Hotine-Marussi Symposium on Mathematical Geodesy, Trento, Italy, September 14-17, 1998.

Kotsakis C., Sideris M.G. (1997) Application of multiresolution filtering in geoid determination. IAG Scientific Assembly, Rio de Janeiro, Brazil, September 3-9, 1997.

Kotsakis C. (2015) On the unexpected usefulness of theory in geodetic problems. Scientific Colloquium in honor of Prof. Armin Gruen, School of Rural and Surveying Engineering, Aristotle University of the Thessaloniki, September 22, 2015, Thessaloniki, Greece.  (full presentation)

Kotsakis C. (2014) The measurement of the Earth and its importance: from antiquity to modern satellite techniques and the role of Geodesy. Cafe Scientifique Series, Joint event organized by the French Institute, the British Council and the Science Center and Technology Museum (NOESIS), February 10, 2014, Thessaloniki, Greece.  (Invited)

Ampatzidis D., Kotsakis C., Katsambalos K. (2012) Realization of an optimal geodetic reference frame in the Hellenic area: open problems and proposals. Scientific Workshop on Tectonic Geodesy, January 25, 2012, Athens, Greece.

Katsambalos K., Kotsakis C., Gianniou M. (2009) Hellenic Terrestrial Reference System 2007 (HTRS07): a regional realization of ETRS89 over Greece in support of HEPOS. ILRS Technical Workshop on SLR Tracking of GNSS Constellations, September 14-19, 2009, Metsovo, Greece.

Kotsakis C. (2009) HEPOS and coordinate transformations. Scientific Workshop on HEPOS, Hellenic Association of Rural and Surveying Engineers & Ktimatologio S.A., February 24, 2009, Athens, Greece.  (Invited)

Kotsakis C. (2009) Accuracy evaluation of the coordinate transformation model between HTRS07 and the official Hellenic Geodetic Reference System of 1987. Scientific Workshop on HEPOS, Hellenic Association of Rural and Surveying Engineers & Ktimatologio S.A., February 24, 2009, Athens, Greece.  (Invited)

Kotsakis C. (2008) Coordinate transformation model between the Hellenic Geodetic Reference System 1987 and the HEPOS reference system. Technical Seminar, KTIMATOLOGIO S.A., December 3-5, 2008, Athens, Greece.

Kotsakis C. (2008) The geodetic framework of HEPOS. Technical Seminar, KTIMATOLOGIO S.A., December 3-5, 2008, Athens, Greece.

Kotsakis C. (2007) Coordinate transformation problems in surveying engineering applications: from the HATT/EGSA87 polynomials to HEPOS. Technical Seminar, Association of Rural and Surveying Engineers of Northern Greece, December 17, 2007, Thessaloniki, Greece.

Kotsakis C. (2007) Coordinate transformation models between the Hellenic Geodetic Reference System of 1987 and the geocentric reference frames of ITRF/ETRF type. Scientific Workshop "HEPOS A new positioning service for Greece: Implementation, challenges and future prospects", School of Rural and Surveying Engineering, National Technical University of Athens, December 6, 2007, Athens, Greece.  (Invited)

Kotsakis C. (2003) The beautiful world of modern geodesy. Seminar presentation, School of Rural and Surveying Engineering, Aristotle University of Thessaloniki, November 10, 2003, Thessaloniki, Greece.

Kotsakis C. (2003) Gravity field and geodynamics. Seminar presentation (ENGO Industry Day), Department of Geomatics Engineering, University of Calgary, May 9, 2003, Calgary, Canada.

Kotsakis C. (2003) Datum transformation issues on the combined analysis of GPS, levelling and geoid data. Canadian Geoid Workshop, May 15-16, 2003, Calgary, Canada.

Kotsakis C. (1999) Aliasing error modeling and optimal non-stationary noise filtering in linear approximation models. ENGO 609 Graduate Seminar Series, Department of Geomatics Engineering, University of Calgary, December 12, 1999, Calgary, Canada.

Kotsakis C. (1999) The long road from collocation to multiresolution approximation. ENGO 607 Graduate Seminar Series, Department of Geomatics Engineering, University of Calgary, June 7, 1999, Calgary, Canada.

Kotsakis C., Sideris M.G. (1998) Spectral analysis and modelling of Faye gravity anomalies and geoid undulations in Canada. Canadian Geoid Workshop, May 14-15, 1998, Ottawa, Canada.

Kotsakis C., Sideris M.G. (1998) Geoid error modeling. Canadian Geoid Workshop, May 14-15, 1998, Ottawa, Canada.

Kotsakis C., Sideris M.G. (1997) Preliminary spectral analysis of gravity anomalies and geoid undulations using the EGM96 geopotential model and local 5' mean Helmert gravity anomalies in Canada. Canadian Geoid Workshop, July 23-25, 1997. Ottawa, Canada.