hul 2004
th either
1 widely
napping,
and the
. by the
eries
:200,000
r HRSC
] Mars96
e
9
eet
nage Map
with the
les and/or
k)
Mercator,
the Topo-
equal-ared
i.e. those
s shown il
longitudes.
ction para
and coor
st lines art
quadrangle
ns increase
fartian Sul"
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
face is divided into 10,372 individual map sheets (10,324
Sinusoidal and 48 Lambert Azimuthal quadrangles) as illus-
trated by Figure |.
As a general rule the series definitions and layout scheme
(Figure 2) are also the guideline for special target maps. Series-
related sheets in larger scales (100k, 50k, etc.) can be easily
derived by appropriate subdivision of the particular sheets.
Moreover, the generation of thematic maps, showing the
scientific findings of other research disciplines, is planned.
Therefore, the Topographic Image Map Mars 1:200,000 series
is expected to be the general guideline for future large-scale
planetary mapping purposes.
3. MAP CONTENT AND SHEET LAYOUT
Important properties of the components of the Topographic
Image Map Mars 1:200,000 or similar products are explained
below. All of these elements can be automatically generated
and compiled to the map sheet using the newly developed carto-
graphic software PIMap, which is described in chapter 4.
3.1 Image Data
The Topographic Image Map Mars 1:200,000 sheets as well as
derived or similar products are based on HRSC color imagery,
i.e. orthophotomosaics featuring a well defined map projection.
Such mosaics are generated in cooperation within the HRSC
Co-Investigator team.
For the integration into the particular map, an image has to be
trimmed to the sheet lines. Previous resampling will be neces-
sary, if the projection or even one of its defining parameters —
e.g. the central meridian of a Sinusoidal projection — differs
between image and desired map sheet. (In case of the
mentioned Sinusoidal projection this resampling causes only a
negligible loss of quality, since solely a shift of image lines is
implied — cf. Snyder, 1987.)
3.0 Contour Lines
A Digital Terrain Model (DTM), representing the topographic
surface information, is calculated by the HRSC team from the
camera's stereo information. With geometric properties similar
to the described orthoimages, such DTM files consist of
grayscale-coded heights.
Within a map sheet the Martian surface — in particular its height
above the areoid — is portrayed by contour lines, which are
derived from the given DTM. Depending on the terrain that is
Mäppeu (plains or scarps respectively) and scale factors on the
other hand contours follow reasonable equidistances. According
to several official map specifications, index lines are always
labeled in such a way, that their altitude is readable while
looking uphill. To distinguish from domes, short and unlabeled
depression contours — regardless, if index or intermediate lines
7 are marked each with a tick or respectively an arrow pointing
into it. An example is given by Figure 4.
Smoothing of the DTM and/or the contour lines themselves can
lead to better cartographic results, i.c. good-looking as well as
Scientifically useful representations of the surface topography
with fewer artifacts. However, this approach has to be further
Investigated as a consequence of gaining more experiences with
HRSC DTM's and their processing.
3.3 Grids
From the beginning the Topographic Image Map Mars
1:200.000 series was foreseen to show both the planeto-
graphic/west as well as the planetocentric/east coordinate sys-
tem (Lehmann et al, 1997). Following latest definitions, the
latter forms the main grid within the map sheets. Basically, the
gridlines hold a spacing of 0.5° but are thinned out towards the
poles due to the meridian convergence. As a second grid the
planetographic/west system is plotted in a similar way but re-
presented by colored tick marks. This has become the common
procedure for other cartographic products of Mars too (e.g,
Rosiek et al., 2003).
As a consequence of described regulations the neat line of a
mapped surface shows the planetocentric/east coordinate SyS-
tem.
3.4 Martian Nomenclature
Martian Nomenclature is regulated by the IAU. Several descrip-
tor terms have been defined to distinguish global land masses
(Terrae, comparable to Earth's continents), regional features
like planes, valleys, etc. and local types, e.g. impact craters.
Over 1500 surface features are named until now. The most
actual and all-embracing dataset of these features, amongst
other things containing the names, location parameters and fea-
ture dimensions, is provided through the Gazetteer of Planetary
Nomenclature by USGS (2004). Based on this information,
Martian features are lettered within a map sheet taking into
account their particular types and sizes.
Map sheets contain landing site markings supplemented with
the mission name as well as the date of touch down.
It is the future plan, to provide map users the information of the
Catalog of Large Martian Impact Craters, which contains seve-
ral data of about 40,000 mostly unnamed craters larger than
5 km in diameter. It is chosen by the Mars Crater Morphology
Consortium being the base of a new Integrated Crater Catalog
(Barlow et al., 2003). However, the revision of that catalog is
not yet finished.
3.5 Map Title and Sheet Designations
Basically, a map is given a title indicating its type. All sheets of
the Topographic Image Map Mars 1:200.000 are naturally
termed with the series name.
Following Greeley & Batson (1990), individual map sheet
designators consist of several codes including the planetary
body, the scale factor, the center of map and the map version.
Thus, “M 200k 40.00N/256.25E OMKT” designates a map of
Mars (M) in scale 1:200 000 (200k), which is centered at 40°
northern planetocentric latitude and 256?15* eastern longitude.
The sheet is based on an orthophotomosaic (OM) and supple-
mented with topographic data (T), i.e. nomenclature and con-
tour lines. It contains color information (K), in this case deno-
ting the image basis. Sheets of the Topographic Image Map
Mars 1:200,000 series solely differ in their center point coor-
dinates. Different from previous regulations and as a con-
sequence of larger scales — particularly with regard to special
target maps having dimensions of less than one degree — the
map center is no longer rounded to full degrees (see Figure 4).
Hence, unclear or even wrong identical designators of neigh-
boring sheets are avoided.
