TMSB Tutorial 3: Mars Rover PanCam Images

article by Ben Lincoln

One of the cool features of NASA's Mars Exploration Rovers ("Spirit" and "Opportunity") is that each of them was equipped with two panoramic cameras ("PanCams"), and each of those was equipped with a different wheel/carousel of bandpass filters.

In addition to making the typical colour and false-colour images available to the public, NASA decided to publish the raw greyscale images on their website (although they are JPEG-compressed). This means that just like the scientists at NASA^[1], you can process these raw images and come up with surprising and interesting results.

In fact, you will probably be using some of the same software: I don't know for certain that the Mars Exploration Rover images are processed using ASU's DaVinci utility, but a lot of the Mars spacecraft data is, and The Mirror's Surface Breaks uses DaVinci's Shadow internally, which is a minor fork I developed of DaVinci. TMSB just makes it a lot easier for non-specialists to get advanced results. See the DaVinci's Shadow page for more information about the main branch of DaVinci.

Mars Exploration Rover Image Data

You can obtain your own source images from NASA's website, or use the example sets at the bottom of this page. To download them yourself, you'll need to decipher the filenames NASA uses. NASA has a guide to what the various elements of the filenames represent.

For purposes of use in TMSB, you are mainly concerned with the third-to-last and fourth-to-last characters of each filename. The fourth-to-last character should be either an "L" or and "R", which indicates the left or right PanCam, respectively. The number after that (the third-to-last character of the filename) indicates which filter was used. For the left PanCam, the filter numbers are:

739nm (338nm bandpass)
753nm (20nm bandpass) - named 0753nm in the TMSB input configuration
673nm (16nm bandpass) - named 0673nm in the TMSB input configuration
601nm (17nm bandpass) - named 0601nm in the TMSB input configuration
535nm (20nm bandpass) - named 0535nm in the TMSB input configuration
482nm (30nm bandpass) - named 0482nm in the TMSB input configuration
432nm (32nm Short-pass) - named 0432nm in the TMSB input configuration
440nm (20) Solar ND 5.0

(You're not going to be using anything with filter numbers 1 or 8 here, if you can even find those images)

For the right PanCam, the filter numbers are:

436nm (37nm short-pass) - named 0436nm in the TMSB input configuration
754nm (20nm bandpass) - named 0754nm in the TMSB input configuration
803nm (20nm bandpass) - named 0803nm in the TMSB input configuration
864nm (17nm bandpass) - named 0864nm in the TMSB input configuration
904nm (26nm bandpass) - named 0904nm in the TMSB input configuration
934nm (25nm bandpass) - named 0934nm in the TMSB input configuration
1009nm (38nm Long-pass) - named 1009nm in the TMSB input configuration
880nm (20) Solar ND 5.0

(Filter #8 from the right PanCam is not used in TMSB, again, assuming you can even find a set that includes it)

In case you are wondering why I used the wavelengths for the band names in this configuration (instead of the filter numbers), it was because I found it really hard to keep track of which filter was which, especially since the wavelength decreases with filter number on the left PanCam, but increases with filter number on the right PanCam. The names are zero-filled to a length of four characters in the TMSB configuration so that files sort in an intuitive and useful way.

With that in mind, here is how to track down a set or two to use, assuming you want to find your own instead of using the examples at the bottom of this page. There are a lot of images on NASA's site, so I suggest finding your own if you have time. Who knows what you'll find!

As usual, there are screenshots below the written instructions.

From the main "All Raw Images" page on NASA's website, choose either Spirit or Opportunity.
On the page with five or six types of camera to select from, you'll want to look through the Panoramic Camera list, and you should look for a "Sol" (Martian day) which has a relatively large number of images listed. Usually if there are complete sets of images from all of the filters, the count will be at least 50, if not 100+.
Pick one of the Sols that looks promising (for example, Sol 695), then click the View Selected Sol button.
On the page for that Sol, in the Full Frame EDR section, look for sequences of images which appear to be the same shot, but in different shades of grey.
Once you find a set that looks promising, click on the first image and examine the URL in your browser's address bar, or hover your mouse pointer over the URL if your browser isn't terrible and shows you the URL that links point to in the status bar at the bottom. Compare the last four characters of the filename (before the ".HTML") to the table above, ignoring the M1. Refer to the screenshots below, because this can be confusing at first. Do this with a couple of the images to make sure that it looks like you'll be able to get a full set for either (or both) of the left and right PanCams.
Once you've found a full (or reasonably full) set, use the View Full Image links on the bottoms of the image pages to download the full-resolution version of each image from the set.
When you have all of the files from the set(s) downloaded, open the images in an image editor and save them as either TIFFs or PNGs (or, alternately, use the JPEG Mars Exploration Rover input configuration included with version 1.1 of TMSB). As you save the files, rename them according to the scheme above. For example, the "L2" image should be named either 0753nm.TIFF or 0753nm.PNG depending on which file format you're using, whereas the "R7" image would be renamed to either 1009nm.TIFF or 1009nm.PNG.
Place each set in its own directory, just like with any other TMSB image set. Keep in mind that the left and right variations are distinct, and should each go in their own directory.

Obtaining Mars Exploration Rover Image Sets

The main image gallery for Spirit

Spirit images for Sol 695

One location to see the image filename

Another location to see the image filename, as well as verifying that it represents what you think it does

Processing Mars Exploration Rover Images in TMSB

Once you have a set of images (either by downloading one of the examples, or following the instructions above), you can process them just like in the TMSB Tutorial 1: Basic Use article, with the following exceptions:

You will need to process the left and right image sets separately, because they use different input configurations.
Because of the increased number of input spectral bands, the number of permutations will increase noticeably.
The results of processing sets from the right PanCam will usually be more subtle than from the left, because nearly all of the filters on the right PanCam are in the near infrared, whereas the left PanCam's filters cover a broader section of the spectrum.

There are no Mars Rover-specific processing configurations at this time, because the images are close enough to the kind I take with my modified DSLR. If you find any special processing that works well with the Mars Rover images specifically, please let me know.

Mars Exploration Rover Processing Screenshots

Use the Left configuration with Left PanCam images

Use the Right configuration with Right PanCam images

Processing Mars Exploration Rover images

Download
File	Size	Version	Release Date	Author
Spirit - Sol 689 - Left PanCam	5 MiB	1.0	2011-02-21	NASA
A sample Mars Exploration Rover image set for use with the TMSB tutorials. This set will generate output images that occupy about 3 MiB on disk for each variation in the selected processing configuration.

Download
File	Size	Version	Release Date	Author
Spirit - Sol 689 - Right PanCam	5 MiB	1.0	2011-02-21	NASA
A sample Mars Exploration Rover image set for use with the TMSB tutorials. This set will generate output images that occupy about 3 MiB on disk for each variation in the selected processing configuration.

Download
File	Size	Version	Release Date	Author
Spirit - Sol 695 - Left PanCam	4 MiB	1.0	2011-02-21	NASA
A sample Mars Exploration Rover image set for use with the TMSB tutorials. This set will generate output images that occupy about 2.5 MiB on disk for each variation in the selected processing configuration.

Download
File	Size	Version	Release Date	Author
Spirit - Sol 695 - Right PanCam	4 MiB	1.0	2011-02-21	NASA
A sample Mars Exploration Rover image set for use with the TMSB tutorials. This set will generate output images that occupy about 2.5 MiB on disk for each variation in the selected processing configuration.

Footnotes

1.	Well, sort of just like.