Locating and Ingesting Image Data¶
This lesson will help you locate planetary datasets that are of interest to you. When you have located the image data, this lesson will help you prepare the data so you can process it in the ISIS3 system.
- Locating and Ingesting Image Data
- Planetary Image Atlas
- Power Tips for the PDS Image Atlas
- Using the Cumulative Index and Table
- Other Planetary Image Data Resources
- Introduction to Importing
- General Importers
- Raw image files
- Importing Mission Data
Planetary Image Atlas¶
Overview of the Planetary Data System PDS Image Atlas
Planetary Image Atlas
The internet has greatly improved the ability to locate and download planetary data. The Planetary Data System (PDS) Planetary Image Atlas is the most comprehensive source for planetary data from current and past planetary missions. The web site provides tools to help you find image data that covers your area of interest in the vast quantities available.
Data can be found for each planet, mission and instrument listed below.
- Magellan: Synthetic Aperature Radar (SAR)
- Clementine: Star Tracker A and B (STAR-A and STAR-B), High Resolution (HIRES), Long Wave Infrared (LWIR), Near Infrared (NIR), and Ultraviolet/Visible (UVVIS)
- Mars Odyssey: Thermal Emission Imaging System THEMIS, and Gamma Ray Spectrometer (GRS)
- Mars Exploration Rovers: Hazard Cameras (HAZCAM), Navigation Cameras (NAVCAM), Microscopic Imager (MI), and Panorama Cameras (PANCAM),
- Mars Global Surveyor: Mars Orbiter Camera MOC, and Mars Orbiter Laser Altimeter (MOLA)
- Pathfinder: Imager for Mars Pathfinder (IMP), Rover (navigation and hazard avoidance system cameras), Alpha Proton X-Ray Spectrometer (APXS), and Meteorology Package (MET)
- Viking Landers: Lander Camera System (LCS)
- Viking Orbiter: Visible (VIS A and B)
- Voyager: Imaging Science Subsystem Narrow Angle (ISS-NA)and Wide Angle (ISS-WA)
- Galileo: Solid State Imaging (SSI) and Near-Infrared Mapping Spectrometer (NIMS)
- Cassini: Imaging Science Subsystem (ISS), Visual and Infrared Mapping Spectrometer (VIMS)
Power Tips for the PDS Image Atlas¶
Finding exactly the data you want for your project can be challenging. The following tips and tools may help to you get the results you want and weed out the ones you don't.
- Increase the size of the latitude and longitude box for search. In your initial searches that use latitudes and longitudes to find image coverage, it is a good idea to increase the bounds of your search. This will help you find images where the camera pointing indicates the image is outside your area of interest but are actually within it. For the Viking mission, your data search boundaries should be increased by as much as 5 degrees to account for pointing errors for the camera.
- Use advanced parameters to refine your search, but don't overdo it. For many data sets there are other search parameters that can be entered in addition to the basic Quick Search options. Look above the main search form for a tool bar with tabs such as Geometry, Instrument, Features, and Time. Click one of the tabs to access additional search parameters related to that particular category. For example, if you're searching for Microscopic Imager images from the Mars Exploration Rover mission, the PDS Image Atlas search page has an option under the Instrument tab to search for images with the dust filter open or closed.
- Use the cumulative index to interrogate the collection. Datasets within the Planetary Data System are not limited to digital image data. For each mission, there are also text files that contain information about the image data. The cumulative index will be covered in more detail later in this lesson.
Using the Cumulative Index and Table¶
Use the cumulative index to interrogate the collection. Data sets within the Planetary Data System are not limited to digital image data. For each mission, there are also text files that contain information about the image data. Two files that can prove useful in locating data that will meet your needs are the Cumulative Index table and the Cumulative Index label. As the name implies, the "table" is added to throughout the life of the mission. You will want to find the final volume of the collection so that all the products will be represented.
- Cumulative Index Table - This file is a table of text that contains information about all the images for a mission up to some date during the mission. You will probably want to find the final volume of a collection so all the products will be represented in the table. The format of the table allows you to use word processing or spreadsheet programs to view the data. You can also write programs or scripts that can interrogate the values and return results. There are many types of information for each image in the collection. You will find information about the instrument that acquired the image, such as the instrument name and the filter used. You can also obtain information that may prove useful in the calibration of an image. Another useful value is the media volume the image data resides on.
- Cumulative Index Label - This file is a text file that describes each field in the cumulative index table.
Where do I find the Cumulative Index and Table files?¶
These files are included in the directory structure for a mission's PDS data distribution. The data distribution is generally designed to be put on CD-ROM, and can be accessed through the PDS Image Atlas. On the Image Atlas front page, click Online Data Volumes for a particular mission. You'll be presented a list of all the volumes (effectively, a CD-ROMs worth of data and information). Click the last volume on the list to get a file list for that volume: you should see a directory named INDEX - this is where the Cumulative Index and Table files are stored, as well as the index and table files for this specific volume.
- PDS Image Atlas click on the Data Volumes Index link on the upper left
- PDS Image Volume in the By Mission column, click on the Full Resolution UVVIS Digital Image Model in the Clementine section
- Clementine CD-ROM/Online Data Volumes under the Mission to the Moon: Full Resolution Clementine UVVIS Digital Image Model section, find the last volume listed. Click on one of the two volume icons.
Other Planetary Image Data Resources¶
The following are just a few sites distributing planetary data.
- The ASU Mars 2001 Odyssey THEMIS data distribution web site provides another source for THEMIS imagery.
- MGS MOC data can be found on USGS PDS Mars Global Surveyor Mars Orbiter Camera (MOC) Image Collection.
Introduction to Importing¶
The job of ingestion programs is to convert the image from another file format to one ISIS3 applications understand (i.e., the ISIS3 cube format). Once a file has been imported, you can use ISIS3 programs to view and manipulate the data. When ingesting data into ISIS3, there are multiple applications in two major categories which can be used to import a file -- choose the one that is best for your data set:
- General Importers - are used to convert image files in non-ISIS3 cube format such as PDS, JPEG or PNG to standard ISIS3 cube format.
- Mission Data Importers - are used to convert specific mission image files such as MOC Wide Angle or THEMIS IR to ISIS3 cube format.
These applications output an ISIS3 formatted cube with an ISIS3 header that contains the minimum required basic keywords for general ISIS3 processing. A few examples of general processing are stretching, filters, and generating histograms. It is important to note that these import applications neither create the necessary labels for mission specific applications such as radiometric calibration and noise removal, nor can the cubes created by them be projected.
Planetary Data System (PDS) labeled image files¶
This application will import a PDS labeled image file into an ISIS3 cube. Only a minimal set of label keywords required by ISIS3 will be put into the output file. No translation of mission specific keywords will be done. Read the help page for pds2isis.
Example command line:
pds2isis FROM=mars_viking.pds TO=mars_viking.cub
Download a sample PDS file (Mars_viking.pds.gz), convert it to an ISIS3 cube, and view it using qview.
Raw image files¶
This application imports raw image files into an ISIS3 cube. Bytes can be swapped if necessary and there are options to create special pixels. It is very important the correct number of lines and samples is provided to the application -- incorrect values will result in a garbled output image.
|Incorrect use of raw2isis to import an image from raw format. We provided 1203 instead of 1204 for samples parameter|
|Correct use of raw2isis to import an image from raw format. This time, we provided the correct value (1204) for the samples parameter|
You must also know if the incoming raw file has a header and what the size of the header is. If the raw file has a header, you must use the parameter "skip" to skip over any header information that is in the raw file. Read the help page for raw2isis for more about the parameters and use of raw2isis.
Example command line:
raw2isis FROM=image.raw TO=image.cub samples=1204 lines=1056 bittype=UNSIGNEDBYTE skip=2137
Download a sample RAW file (Mars_viking.raw.gz), convert it to an ISIS3 cube, and view it using qview. Hint: the image is 1024 lines by 1024 samples, and has a 4019 byte header.
Video Image Communication and Retrieval (VICAR) image files¶
This application imports VICAR formatted image files into ISIS3 cubes. No translation of mission specific VICAR labels is done. Read the help page for vicar2isis.
Example command line:
vicar2isis FROM=mexpress_vicar.img TO=mexpress_vicar.cub
Download a sample VICAR file (Mexpress_vicar.img.gz), convert it to an ISIS3 cube, and view it using qview.
Importing Mission Data¶
Mission-specific ingestion applications are used to ingest data distributed for specific missons. These applications will output ISIS3 formatted cube files that have mission-specific keywords in the labels. These keywords are required for calibration and projection processing tasks. Often, there will be mission specific applications for calibrating, correcting, analyzing, and enhancing a mission data set. These programs require the keywords from the mission-specific ingestion applications and will not work properly if a general ingestion application is used.
- ciss2isis: Import a Cassini ISS VICAR image file into ISIS
- moc2isis: Import PDS formatted MOC image cube into ISIS3 format cube
- thm2isis: Import a THEMIS IR/VIS RDR or EDR
- hi2isis: Import HiRISE EDR images into ISIS3 cube format
- vik2isis: Import PDS formatted Viking EDR into ISIS3 format cube
- Find and download a Mars Global Surveyor Mars Orbiter Camera image (hint: the "Download Standard Compressed Data Product" link will give you a file ending in .imq - this is a PDS formatted MOC
- Convert the MOC file to an ISIS3 cube using moc2isis
- View the imported file using qview