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Commit 26e373ca authored by Carlos H. Brandt's avatar Carlos H. Brandt
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Update HRSC readme

parent 5e049db5
......@@ -11,27 +11,66 @@ As explained in [Scholten et al, 2005] (hereafter S05) and overviewed in [Neukem
* Level-4: DTMs and orthoimages.
We are interested in Level-4 data: DTM/DEM. In particular, data taken from
instrument's Nadir setup; Figure [S05 Fig-1] pictures the different lines fo
instrument's Nadir observations; Figure [S05 Fig-1] pictures the different lines fo
sight according to the different CCDs (Nadir represented as `ND`):
![HRSC/SRC technical parameters][S05 Fig-1]
[S05 Fig-1]: Scholten_etal_2005-Fig1_Technical_Params_HRSC_SRC.png
## Data access
The following links have further information about this dataset:
* Ortho and DTM data: https://pds.nasa.gov/ds-view/pds/viewDataset.jsp?dsid=MEX-M-HRSC-5-REFDR-DTM-V1.0
* HRSC user guide: https://ode.rsl.wustl.edu/mars/pagehelp/quickstartguide/index.html?hrsc.htm
* PDS node: https://pds-geosciences.wustl.edu/missions/mars_express/hrsc.htm
* ODE: https://ode.rsl.wustl.edu/mars/indexDatasets.aspx
## Data archive
### ODE - PDS
[PDS Geosciences Node]: https://pds-geosciences.wustl.edu/mex/mex-m-hrsc-5-refdr-dtm-v1/mexhrs_2001/
[Browse under orbit 0010]: https://pds-geosciences.wustl.edu/mex/mex-m-hrsc-5-refdr-dtm-v1/mexhrs_2001/browse/0010/
HRSC dataset is stored in PDS format (see [../../PDS.md]).
Interfaces to access the archive are provided at:
* https://pds-geosciences.wustl.edu/missions/mars_express/hrsc.htm ;
* https://ode.rsl.wustl.edu/mars/indexDatasets.aspx .
In particular, at https://pds-geosciences.wustl.edu/mex/mex-m-hrsc-5-refdr-dtm-v1/mexhrs_2001
we will find HRSC level-4 data of our interest.
As a PDS archive, we will find there a well defined, standard files/directories
structure.
If we are going straight for the data, our interest is on directories
`browse` and `data`; `browse` provides a _view_ of each data file in a commonly
used format (`PNG`), and `data` provides the actual scientific data.
Metadata, documentation and other support material are found in the
other directories.
> The section below, [Archive Summary] and [Exploring the archive] go into the
structural and content of this archive. For detail I would like to defer the
reader to those sections.
The data (in `data` and `browse`) are split after the mission _orbit-ID_,
inside each _orbit_ directory we will find the respective images.
The number of images is not fixed, but we can generally expect on image
per sensor and per product -- DTM/DEM.
The following list of files was taken from section [Explorin the archive]
and represent the list of files found in orbit `0010`:
```
h0010_0009_bl4.img
h0010_0009_da4.img
h0010_0009_dt4.img
h0010_0009_gr4.img
h0010_0009_ir4.img
h0010_0009_nd4.img
h0010_0009_re4.img
```
. Our interest is over files with indixes `nd`,`dt`,`da` for we want
Nadir, DTM, DEM view/content.
We notice there are no Label (metadata) files accompanying the images.
That's because the (label) metadata is positioned at the header of image files.
In the header we will find virtually all the information we need to know
about each image.
To extract the metadata from the data files is simple and can be done from a
typical shell command, since PDS Labels are _text_ data and obey a formal
syntax (ending always in `END`):
```
$ awk '{print $0; if($0 ~ /^END/){if($1 !~ /END_/){exit}}}' <datafile.img>
```
In ODE there is a nice interface to explore the PDS archive they have.
It is a PDS archive.
#### Archive summary
......@@ -104,6 +143,7 @@ The `BROWSE` directory mirrors/mimic the `DATA` structure.
> - generation of Digital terrain Models and Orthorectification of image data [19,20]
#### Exploring the archive
Our interest now is to access the Level-4, DTM data; Which is under
......@@ -146,6 +186,226 @@ The image type infixes mean as follows:
What we want is primarily the Nadir (ND) observations, and the DTM (DA and DT)
products.
Those, for instance are given below:
h0010_0009_nd4 | h0010_0009_da4 | h0010_0009_dt4
--- | --- | ---
![h0010_0009_nd4.jpg](assets/h0010_0009_nd4.jpg) | ![h0010_0009_da4.jpg](assets/h0010_0009_da4.jpg) | ![h0010_0009_dt4.jpg](assets/h0010_0009_dt4.jpg)
With Label files as below (ex. `h0010_0009_nd4.lbl`):
```
PDS_VERSION_ID = PDS3
RECORD_TYPE = UNDEFINED
SOURCE_PRODUCT_ID = "H0010_0009_ND4.IMG"
RELEASE_ID = 0001
REVISION_ID = 0001
^BROWSE_IMAGE = "H0010_0009_ND4.JPG"
PRODUCT_ID = "H0010_0009_ND4.JPG"
DATA_SET_ID = "MEX-M-HRSC-5-REFDR-DTM-V1.0"
INSTRUMENT_ID = HRSC
INSTRUMENT_HOST_ID = MEX
PRODUCT_CREATION_TIME = 2008-06-10T10:54:41.000Z
OBJECT = BROWSE_IMAGE
ENCODING_TYPE = JPEG
LINES = 2027
LINE_SAMPLES = 556
SAMPLE_TYPE = UNSIGNED_INTEGER
SAMPLE_BITS = 8
END_OBJECT = BROWSE_IMAGE
END
```
In the `EXTRAS` directory there are PNG files with:
```
- the DTM (as shaded relief)
- the nadir orthophoto
- a RGB orthophoto
(all with 500 m/pixel resolution)
The following filenaming convention was applied:
Hoooo_nnnn.PNG
oooo is the orbit number
nnnn is the number of the image strip in this orbit
```
The corresponding image (10,9) shaded relief, nadir and RGB orthophotos:
![H0010_0009 DTM-ND-RGB](assets/h0010_0009.png)
#### Data access
Now that we browsed the images of orbit 0010, and we want `ND4`,`DT4`,`DA4`
files, we go to `DATA` directory, at the same address -- `0010/` -- to check
for the corresponding IMG data:
```
h0010_0009_bl4.img
h0010_0009_da4.img
h0010_0009_dt4.img
h0010_0009_gr4.img
h0010_0009_ir4.img
h0010_0009_nd4.img
h0010_0009_re4.img
```
`DATA` directory has all the IMG files we expected but no LBL files, with IMG
metadata. That means that the `.img` files here have the Label content in IMG
headers.
Effectively, the header from `h0010_0009_nd4.img` can be read from the image
with an `awk` call:
```
$ awk '{print $0; if($0 ~ /^END/){if($1 !~ /END_/){exit}}}' h0010_0009_nd4.img
```
, which output the IMG's Label content.
Section [Metadata] presents the content of such Label/header.
##### Metadata
In PDS Label files/content we find the concise description of the data of
reference (see [/datasets/PDS.md](/datasets/PDS.md)).
Labels are very complete in their description of their corresponding data,
with information about the instrument, observation, as well as derived
information like an image's footprint.
For instance, the section about `DIGITAL TERRAIN MODEL DEFINITIONS` from Label
files "`ND4`,`DT4`,`DA4`" provide data on how/some different between them:
* `h0010_0009_nd4.lbl`:
```
/* IDENTIFICATION DATA ELEMENTS */
FILE_NAME = "H0010_0009_ND4.IMG"
DATA_SET_ID = "MEX-M-HRSC-5-REFDR-DTM-V1.0"
DETECTOR_ID = MEX_HRSC_NADIR
EVENT_TYPE = "MARS-REGIONAL-MAPPING-Vo-Im-Tc"
INSTRUMENT_HOST_ID = MEX
INSTRUMENT_HOST_NAME = "MARS EXPRESS"
INSTRUMENT_ID = HRSC
INSTRUMENT_NAME = "HIGH RESOLUTION STEREO CAMERA"
MISSION_NAME = "MARS EXPRESS"
MISSION_PHASE_NAME = MC_Phase_0
PROCESSING_LEVEL_ID = 4
PRODUCT_CREATION_TIME = 2008-06-10T10:54:41.000Z
PRODUCT_ID = "H0010_0009_ND4.IMG"
RELEASE_ID = 0001
REVISION_ID = 0001
/* TIME DATA ELEMENTS */
SPACECRAFT_CLOCK_START_COUNT = "1/0021823325.32303"
SPACECRAFT_CLOCK_STOP_COUNT = "1/0021823574.56834"
START_TIME = 2004-01-10T14:02:37.354Z
STOP_TIME = 2004-01-10T14:05:52.359Z
(...)
/* DIGITAL TERRAIN MODEL DEFINITIONS */
GROUP = MEX:DTM
MEX:DTM_A_AXIS_RADIUS = -1e+32 <km>
MEX:DTM_B_AXIS_RADIUS = -1e+32 <km>
MEX:DTM_C_AXIS_RADIUS = -1e+32 <km>
MEX:DTM_DESC = "N/A"
MEX:DTM_MISSING_DN = -2147483648
MEX:DTM_OFFSET = -1e+32 <m>
MEX:DTM_SCALING_FACTOR = -1e+32 <m>
END_GROUP = MEX:DTM
```
* `h0010_0009_dt4.lbl`:
```
/* IDENTIFICATION DATA ELEMENTS */
FILE_NAME = "H0010_0009_DT4.IMG"
DATA_SET_ID = "MEX-M-HRSC-5-REFDR-DTM-V1.0"
DETECTOR_ID = "N/A"
EVENT_TYPE = "MARS-REGIONAL-MAPPING-Vo-Im-Tc"
INSTRUMENT_HOST_ID = MEX
INSTRUMENT_HOST_NAME = "MARS EXPRESS"
INSTRUMENT_ID = HRSC
INSTRUMENT_NAME = "HIGH RESOLUTION STEREO CAMERA"
MISSION_NAME = "MARS EXPRESS"
MISSION_PHASE_NAME = MC_Phase_0
PROCESSING_LEVEL_ID = 4
PRODUCT_CREATION_TIME = 2008-06-10T10:54:41.000Z
PRODUCT_ID = "H0010_0009_DT4.IMG"
RELEASE_ID = 0001
REVISION_ID = 0001
/* TIME DATA ELEMENTS */
SPACECRAFT_CLOCK_START_COUNT = "1/0021823325.32303"
SPACECRAFT_CLOCK_STOP_COUNT = "1/0021823574.56834"
START_TIME = N/A
STOP_TIME = N/A
(...)
/* DIGITAL TERRAIN MODEL DEFINITIONS */
GROUP = MEX:DTM
MEX:DTM_A_AXIS_RADIUS = 3396.0 <km>
MEX:DTM_B_AXIS_RADIUS = 3396.0 <km>
MEX:DTM_C_AXIS_RADIUS = 3396.0 <km>
MEX:DTM_DESC = HEIGHT_ABOVE_SPHEROID
MEX:DTM_MISSING_DN = -32768
MEX:DTM_OFFSET = 0.0 <m>
MEX:DTM_SCALING_FACTOR = 1.0 <m>
END_GROUP = MEX:DTM
```
* `h0010_0009_da4.lbl`:
```
/* IDENTIFICATION DATA ELEMENTS */
FILE_NAME = "H0010_0009_DA4.IMG"
DATA_SET_ID = "MEX-M-HRSC-5-REFDR-DTM-V1.0"
DETECTOR_ID = "N/A"
EVENT_TYPE = "MARS-REGIONAL-MAPPING-Vo-Im-Tc"
INSTRUMENT_HOST_ID = MEX
INSTRUMENT_HOST_NAME = "MARS EXPRESS"
INSTRUMENT_ID = HRSC
INSTRUMENT_NAME = "HIGH RESOLUTION STEREO CAMERA"
MISSION_NAME = "MARS EXPRESS"
MISSION_PHASE_NAME = MC_Phase_0
PROCESSING_LEVEL_ID = 4
PRODUCT_CREATION_TIME = 2008-06-10T10:54:41.000Z
PRODUCT_ID = "H0010_0009_DA4.IMG"
RELEASE_ID = 0001
REVISION_ID = 0001
/* TIME DATA ELEMENTS */
SPACECRAFT_CLOCK_START_COUNT = "1/0021823325.32303"
SPACECRAFT_CLOCK_STOP_COUNT = "1/0021823574.56834"
START_TIME = N/A
STOP_TIME = N/A
(...)
/* DIGITAL TERRAIN MODEL DEFINITIONS */
GROUP = MEX:DTM
MEX:DTM_A_AXIS_RADIUS = -1e+32 <km>
MEX:DTM_B_AXIS_RADIUS = -1e+32 <km>
MEX:DTM_C_AXIS_RADIUS = -1e+32 <km>
MEX:DTM_DESC = "Height above equipotential surface
described by potential model GMM3 (PDS
dataset MGS-M-MOLA-5-MEGDR-L3-V1.0)"
MEX:DTM_MISSING_DN = -32768
MEX:DTM_OFFSET = 0.0 <m>
MEX:DTM_SCALING_FACTOR = 1.0 <m>
END_GROUP = MEX:DTM
```
### Keywords
......
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