602
October 2020
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
verted from the Provisional Courland System to the General
Latvian Triangulation Net by a graphical adjustment (trian-
gle by triangle) based on the comparison of first-order values.
After the lower-order trig in Courland was converted to terms
of the General Latvian Triangulation Net, the Final DHG
Pulkovo 1932 coordinate for all Latvia were computed. These
coordinates were published in 1943 as a second edition
Aus-
gabe Endwerte Koordinatenkartei
by the Kriegs-Karten und
Vermessungsamt, Riga. In the Fall of 1944 the publication
of the
Koordinaten-Verzeichnis
(trig books) was begun. The
coverage of these books is scanty. Also, it is noted that there
are differences of up to a meter, at some stations, between
the
Koordinaten-Verzeichnis
values and those from the sec-
ond edition
Koordnatenkartei
. Is appears that this difference
is accounted for by the fact that some of the Latvian traverse
points (as included in the second edition
Koordinatenkartei
)
were resurveyed by the German Army and consequently were
listed in the
Koordinaten-Verzeichnis
books by the German
Survey values.” To convert from DHG Pulkovo 1932 Datum
Grid coordinates to European Datum 1950 coordinates on
the UTM Grid, zone 34, use the following: (UTM Northing)
= 0.9996056758 * (DHG Northing) + 0.0000176163 * (DHG
Easting) + 828.01, and (UTM Easting) = 0.9996056758 *
(DHG Easting) + 0.0000176163 * (DHG Northing) + 365.98.
The NIMA published values for that general region of Europe
from European Datum 1950 to WGS 84 are ∆X = –87m ±3m,
∆Y = –95m ±3m, and ∆Z = –120m ±3m. The NIMA published
values for System 42 Datum (in Latvia) to the WGS 84 Datum
are ∆X = +24m ±2m, ∆Y = –124m ±2m, and ∆Z = –82m ±2m.
U
pdate
“(The) origin of Latvian Coordinate System LKS-92 definition
was based on two GNSS campaigns in 1992 and 2003. There
are two continuously operating reference networks in Latvia:
LatPos and EUPOS
®
-Riga. GNSS stations of these networks
have fixed coordinate values in LKS-92. At the Institute of
Geodesy and Geoinformatics of the University of Latvia both
LatPos and EUPOS
®
-Riga station daily coordinate values are
calculated. The coordinate differences between epochs 1989.0
and 2018.5 were obtained for LatPos and EUPOS
®
-Riga sta-
tions, expressed in ITRF14. ITRF reflects the motion of Eur-
asian plate in global frame of the Earth and ETRF89 system
reflects the intraplate motion. Mean yearly coordinate compo-
nents in ETRF89 were analysed. Comparison of LatPos and
EUPOS
®
-Riga station coordinate components in ETRF89,
LKS-92 and ETRF2000 coordinate systems was performed.
Future of Latvian coordinate system LKS-92 is discussed.”
Baltic J. Modern Computing, Vol. 7 (2019), No. 4, 513-524
“According to the decision of IAG Reference Frame Sub-
commission for Europe (EUREF) the EVRF2007 solution as
the vertical reference has to be deployed in EU countries. The
new height system
LAS-2000,5
had been enacted as the Eu-
ropean Vertical Reference System’s
EVRF2007
realization in
Latvia and the new geoid model LV’14 had been introduced
by Latvian authority Latvian Geospatial Information Agency.
However, the appreciation of the quality of quasi-geoid mod-
el LV’14 is rather contradictious among the users in Latvia.
The independent estimate and comparison of the two Latvian
geoid models developed till now has been performed by the
Institute of Geodesy and Geoinformatics. Previous geoid mod-
el LV98 which was developed for
Baltic-1977
height system
almost 20 years ago is outdated now. Preparatory actions de-
scribed in order to fulfil the task of comparison the geoids in
two different height systems. The equations and transforma-
tion parameters are presented in this article for the normal
height conversion from
Baltic-1977 height system to the Latvi-
an realization named LAS-2000,5.”
Balodis, J., Morozova, K., Silabriedis, G., Kalinka, M., 2016.
Changing the national height system and geoid model
in Latvia.
Geodesy and Cartography
42(1):20-24. DOI:
10.3846/20296991.2016.1168009.
The contents of this column reflect the views of the author, who is
responsible for the facts and accuracy of the data presented herein.
The contents do not necessarily reflect the official views or policies of
the American Society for Photogrammetry and Remote Sensing and/
or the Louisiana State University Center for GeoInformatics (C
4
G).
This column was previously published in
PE&RS
.
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