PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
August 2016
591
to someday have a reliable geoid model for the entire country
that will enable GPS leveling techniques to be implemented.
U
pdate
Zone transformation parameters for UTM zones were
recalculated in 2005 and in 2008. A complete airborne gravity
survey of Mongolia was carried out in two fall campaigns 2004-
2005 by the Danish National Space Center. Absolute gravity
was observed in 2006-2007. A Mongolian geoid height model
was produced with 16 cm accuracy for the whole country and
2-5 cm accuracy for the city of Ulaanbaatar. Transformation
parameters and the geoid height model are accessible
from ALAGaC web page for the public (Munkhtsetseg, D.,
Geodetic Network and Geoid Model of Mongolia
,
isprs.
org/proceedings/XXXVIII/7-C4/121_GSEM2009
).
A
cknowledgement
Thanks to Mr. Cole Billeaud for research assistance regarding
the update.
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
.
advice on commercial launch services and costs would likewise
be helpful. In the chapter on pushbroom imagers, the author
expresses the dwell time as a function of the angle subtended
by a resolution element, the subsatellite point velocity, and
the altitude, as
In other references it is stated that this dwell time should
always be less than one-half this value to avoid unacceptable
image smear. He does imply this later in the chapter on
Submeter Imaging.
Overall this book is a valuable contribution to the remote
sensing literature. No doubt much of the information is
available in specialized texts and journals on optics and
aerospace engineering, but the author, guided by his unique
experience, brings this information together in way that
is accessible and interesting to the photogrammetrist,
cartographer, or remote sensing analyst.
Book Review
Or,
Total number of checkpoints required for the
project =
100 (for the 1
st
2,500 km
2
) + 105 (for the
remaining 10,449 km
2
) = 205 checkpoints distributed as
follow:
118 checkpoints within the NVA area
87 checkpoints within the VVA area
Please remember that the new ASPRS standard states,
“
The recommended number and distribution of NVA and VVA
checkpoints may vary depending on the importance of different
land cover categories and client requirements”.
Therefore, you
have some flexibility in balancing the number of VVA and
VVA checkpoints depending on your project and your client
understanding of the issue.
**Dr. Abdullah is Senior Geospatial Scientist and Associate at Woolp-
ert, Inc. He is the 2010 recipient of the ASPRS Photogrammetric (Fair-
child) Award.
The contents of this column reflect the views of the author,
who is responsible for the facts and accuracy of the data pre-
sented herein. The contents do not necessarily reflect the offi-
cial views or policies of the American Society for Photogram-
metry and Remote Sensing and/or Woolpert, Inc.
“For vertical testing of areas >2,500 km2, add five
additional vertical checkpoints for each additional
500 km2 area. Each additional set of five vertical
checkpoints for 500 km2 would include three
checkpoints for NVA and two for VVA”
Mapping Matters
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