MEX HRSC High Resolution Images, DTMs, and Mosaics of Phobos (PHOBOS)
PHOBOS – High Resolution Images, DTMs, and Mosaics of Phobos
Instrument: High Resolution Stereo Camera
PDS Data Set ID: MEX-M-HRSC-5-REFDR-PHOBOS-MAPS-V1.0DOI: 10.5270/esa-sin3ov8
For more information about HRSC PHOBOS products, see the PHOBOS Product EAICD.
The High Resolution Stereo Camera (HRSC) High Resolution Images, DTMS, and Mosaics of Phobos (PHOBOS) data products are a collection of 16-bit orthorectified high resolution images for the nadir and the 4 color channels, 16-bit digital terrain models, and 8-bit orthoimage mosaics taken by the HRSC, specifically of Mars’ moon Phobos. The orthoimages are based on the DTMs, and are thus available exclusively for areas covered by the DTMs.
DTM generation is based on multi-image matching using pyramid-based least-squares correlation after pre-processing. 3D Point determination by least-squares forward intersection is followed by DTM grid interpolation (distance weighted averaging within a local interpolation radius). The overall process involves automatic procedures in combination with standardized quality checks. DTM generation uses adjusted orbit and pointing data that are referenced to a common global control point network.
The north pole is represented in a mosaic from -20° poleward, the south pole is represented in a mosaic from +20° poleward, both projected in Polar Stereographic projection. Two DTMs represent the equatorial part of Phobos, both having a latitudal extent from -60° to 60° and a longitudinal extent of 180°. The DTMs of the equatorial region are provided in Mercator projection. Phobos’ leading hemisphere is centered at 0° latitude, 90° western longitude. Phobos’ trailing hemisphere is centered at 0° latitude, 270° western longitude.
The DTM and the adjusted orientation data are finally applied for orthoimage production. All individual orthoimages are projected twice in Orthographic and Equidistant projections centered at the latitude and western longitude of the image center. The global orthoimage mosaic is derived from 10 HRSC images and in Simple Cylindrical projection centered at 0° latitude and 0° longitude west. The poles are represented by an image mosaic from ±55° poleward, projected in Polar Stereographic projection. The equatorial part of Phobos is provided as two mosaic, both having a latitudal extent from -57° to 57°, and each with a longitudinal extent of 180°. The mosaics of the equatorial region are provided in Mercator projection and like the DTM data centered at 0° latitude, 90° western longitude and at 0° latitude, 270° western longitude.
PHOBOS data products are processed by software which performs the following steps:
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Remove all transmission headers to get the original camera data
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Sort camera data by sensor and combine them with the housekeeping data
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Decompress the data
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Radiometric calibration of the data
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Calculate footprints of every image file
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Geometric calibration and map projection
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Improvement of orbit and attitude data
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Generation of Digital Terrain Models and Orthorectification of image data
HRSC PHOBOS DTM products have the following file names:
HRSC_DTM_DT5_ppp_aad_oooW.JP2 (with additional binary image file and detached PDS label)
where:
HRSC = 4-digit camera name
DTM = digital elevation model
DT = height values are referenced to a sphere
5 = processing level
ppp = 3-digit projection type
EQU = Equidistant
MER = Mercator
STE = Stereographic
aa = 2-digit center latitude
d = latitude direction
N = North
S = South
ooo = 3-digit center longitude
W = West
HRSC PHOBOS Orthoimage products have the following file names:
Hnnnn_mmmm_dd4_ppp_aad_oooW.JP2 (with additional binary image file and detached PDS label)
where:
nnn = 4-digit orbit number
mmmm = 4-digit number of the image in this orbit
dd = sensor name
ND = nadir
BL = blue
GR = green
IR = near IR
RE = red
4 = processing level
ppp = 3-digit projection type
EQU = Equidistant
ORT = Orthographic
aa = 2-digit center latitude
d = latitude direction
N = North
S = South
ooo = 3-digit center longitude
W = West
HRSC PHOBOS Mosaic files have the following file names:
HRSC_MOS_dd5_ppp_aad_oooW.JP2 (with additional binary image file and detached PDS label)
where:
HRSC = 4-digit camera name
MOS = Mosaic
dd = sensor name
ND = nadir
BL = blue
GR = green
IR = near IR
RE = red
SR = super resolution
5 = processing level
ppp = 3-digit projection type
EQU = Equidistant
MER = Mercator
STE = Stereographic
aa = 2-digit center latitude
d = latitude direction
N = North
S = South
ooo = 3-digit center longitude
W = West
In ODE, PHOBOS products have one of the following Product IDs:
HRSC_DTM_DT5_PPP_AAD_OOOW.JP2
HNNNN_MMMM_DD4_PPP_AAD_OOOW.JP2
HRSC_MOS_DD5_PPP_AAD_OOOW.JP2