For example, such software could display the actual coordinates on Mars of the pixels you are looking at, allow you to measure features directly in physical units, or stitch together images based on their absolute location on the planet. A number of GIS (Geographical Information Systems) applications use GeoTIFF; many on our science team have been waiting patiently for this feature to be rolled out.

We have already begun to produce RDRs with GeoTIFF, and they will start appearing in our weekly releases. At some point, a major reprocessing effort will be underway to bring this feature (and others) to all of our pre-existing products.

This brings up the topic of versioning: namely, how to tell which version of a HiRISE product you are working with.

Every HiRISE product has a line in the PDS label with the DATA_SET_ID. Every released HiRISE product to date shows that it has a DATA_SET_ID version of 1.0. The GeoTIFF RDR’s have a DATA_SET_ID showing version 1.1. This 1.1 version of our RDR processing also contains the updated color stretches described in a previous post. Later this year, that version number will likely be bumped up again when our improved calibration algorithms are put into production.

In addition, every HiRISE PDS product also has a line in the label with the PRODUCT_VERSION_ID. And every released HiRISE product to date has a PRODUCT_VERSION_ID of 1. When we make a new version of a released product, the version number will be incremented. If that new version is then released, it will replace the older version. We will only replace products with newer versions after a process of validation.

We’re halfway through a major update to our production pipelines that allows us to create, store, and reprocess these newer versions without effecting the released versions. This version number will only increase by integer amounts, and will never “skip”.

View Images

There are, as always, many magnificent images here. Some of the noteworthy observations are:

PSP_001521_2025 and PSP_001501_2280: On the HiRISE web site you can see diagrams made by Tim Parker show the locations of various parts (lander, backshell, heatshield or parachute) for Viking Lander 1 and Viking Lander 2. It’s possible they aren’t in the color strip (I haven’t found them)!

PSP_001508_1245 and PSP_001510_2195: These two exhibit a “glow” pattern of saturated pixels due to high TDI (Time Delay Integration) settings on the blue-green CCDs. (All of the exposure settings are chosen for each observation based on a photometric model of the scene).

PSP_001538_2035: This is a rim-to-rim section across a crater called Tooting that is about 30 kilometers in diameter. It’s also interesting to note how the altitude of the rims, when combined with the large off-nadir roll angle (23 degrees), leads to an oddly bowed geometric projection. But it is correct; as the terrain rose, fell, and rose again from HiRISE’s angled point of view, the center of the ground track deviated slightly east or west from a true great-circle line.

PSP_001558_1325 and PSP_001593_2635: These dune fields are striking, forming incredible patterns.

PSP_001582_2245: Looking like a super-sized area of dried mud, the polygonal cracks in this image are amazing.

Updated (2008-Apr-10)

I’ve prepared this ugly table that outlines each of the products now available (excluding the raw EDRs). So reading the columns from left to right: there are three types of “NOMAP” products, two types of lossy “QLOOK” (Quicklook) RDRs, and two types of lossless RDRs.

With that as a reference, now I’ll try to define everything more precisely.

“NOMAP”

Non map-projected product. Always lossy compressed for smaller size and quicker viewing. These are not formal Planetary Data System products; they’re “special”, meaning there is no PDS label and no Software Interface Specification describing them. Available for IRB, RGB and RED.

RDR

Reduced Data Record: reduced in the sense of refined or processed, not raw data. Formal PDS products with accompanying labels and a detailed SIS document describing their format and processing steps. Available both in lossless and quicklook formats for both RED & COLOR.

“QLOOK”

Quicklook: a special product that is a lossy compressed version of the RDR. In a normal RDR, all of the original data is retained. But with a quicklook, some of the highest resolution detail is discarded to make for quicker viewing.

RED

The image obtained by the red-filtered CCDs. It will be over the full swath width, typically data from all ten red CCDs. Covers the visible wavelength band from 550 to 850 nanometers.

IR

Infrared. Covers the near-IR wavelengths from 800-1000 nanometers.

BG

Blue-Green, visible wavelengths from 400-600 nm.

COLOR

A color RDR. It contains data from the IR, BG and center RED ccds. Typically this will be a skinny strip (”center swath”) inside a skinny strip, or as I like to say, the bacon-strip effect.

IRB

An enhanced color NOMAP. It has the same color bands as the RDR: IR, RED and BG.

RGB

An enhanced color NOMAP. It contains only data from the RED and BG. The blue is derived from the difference between the RED and BG. The color bands are RED, BG and the synthetic blue.

EDR

Experiment Data Record, a formal PDS product that is raw uncompressed data with a label header.

Note: we will be working towards making all of these products available for all prior releases.

This is an ambitious effort. Originally (years before HiRISE), Clickworkers was used to tag craters on Mars, helping pin down the relative ages of various regions. This time around, you identify a dozen or so possible feature types, then move on to the next image. So you have to be a little more discerning, though examples are provided.

I was just looking at the sizes of our images to date. We’re coming up on one thousand images that have been map projected. And it looks like we just recently passed the one million megapixel mark (one thousand gigapixels, or one terapixel!) in the geometrically projected ones (when rotated so that North is up, there tends to be a lot of empty pixels framing the images).

Assuming a standard screen size of 1.25 megapixels (1280×1024), that is 800,000 screenfuls. If you looked at one per second, it would take you almost ten days to view it all! But one thousand volunteers could get through it in a day, and spend 100 seconds per image, which seems reasonable. [Though of course they'll need time for sleep, etc!]

The idea of using human brain power as a sort of massively distributed computation engine (shades of The Matrix) has come a long way. Amazon’s Mechanical Turk pays volunteers for tasks such as identifying features, translating documents or answering questions. It was recently used in the search for a person (computer scientist Jim Gray) missing at sea. Volunteers viewed over a half million images, covering 3,500 square miles of ocean, though unfortunately his sailboat did not turn up.

Still, ‘crowdsourcing‘ (as Wired called it) seems like it will continue to be an efficient way to perform tasks that computers are currently very poor at. Here at the Lunar and Planetary Lab, it has also been used by Spacewatch to find Earth-approaching asteroids. So, essentially, you could help save the planet in a real-life version of the classic game Asteroids! Clickworkers also has a program where you can tag Mars Global Surveyor images, scouting interesting locations for HiRISE to target.

We can’t let the machines have all the fun!

The HiStitch pipeline combines the matching HiCal products for the same CCD into one more-or-less lined up CCD cube file. HiccdStitch combines these HiStitch cubes into RED, IR, and BG mosaics.

Both pipelines take some time, as overlapping pixels are accounted for and brought together. After these mosaics are created, additional steps create smaller jpeg files for easier viewing, and full-sized jpeg2000 files. We use these jpeg2000 files for validating our images.

There are later pipelines, but we first validate the HiccdStitch products: Did the previous pipelines work correctly? Did the uplink team command the camera correctly? Is there haze or clouds obscuring our view of the surface?

If everything looks good, and we have received the correct reconstructed SPICE ephemeris data, then the geometry pipelines are invoked. These pipelines project the images mathematically to a model of Mars and add geometry data to the images so that each pixel becomes a point on Mars with latitude and longitude coordinates.

We are waiting for reconstructed SPICE ephemeris data, which comes out every Wednesday – starting next week – before sending these data through our geometry pipelines, and ultimately releasing them to the scientific community and public. Last time, we forced images through our geometry pipelines using predicted SPICE kernels; we do not want to double our workload by continuing that practice. The SPICE kernels released next Wednesday will cover some of the images captured this week.

Once the images have been visually and statistically validated and the matching SPICE kernels have arrived, one of the downlink folks will send the images through the geometry pipelines. We also need to get a select group of captions written and automatic caption information generated for the rest.

We are producing JPEG2000 products now in addition to smaller jpeg browse images, to be ready for our viewing client when it is ready for public release. However, there are many different JPEG2000 viewers and plugins already out there to start practicing with. One example is ExpressView from LizardTech.

Once we are on a roll, the data release will be steady and no one will be able to keep up with the wealth of Mars data coming in. Until the first public release of PSP images, we will try to provide here on HiBlog more details about the many tasks that must still be completed.

Audrie, Tahirih and I did not previously appear in pictures on HiBlog because during transition imaging we were busy working in our offices and Tuvas for some reason did not visit us. We feel so left out (joking)! The three of us make up HiRISE Downlink Operations, which includes downloading new images, processing them, and image validation (the Student Validators also participate in this task). Audrie also works on instrument monitoring and safety. Tahirih also does most of the geometry processing. I also eat cheetos and chocolate cake. When Kite is not busy with HiRISE Uplink tasks – which is generally NEVER – she is blasting her way out of impossible situations that often involve walking carpets.

1. The image is taken by the HiRISE camera, and is stored in up to 28 channels, two for each of the 14 CCD arrays of the camera. Each channel covers about half of the image. Of the 14 CCDs, 10 are red CCDs, two are blue-green, and two are near-infrared. The color CCDs are aligned with the center red CCDs.
2. The image is placed inside a buffer on MRO, awaiting transmission to Earth, along with science data from the other instruments on MRO.
3. The image is received in packets by the Deep Space Network (DSN).
4. After 4 hours of collecting data at the DSN, the Jet Propulsion Laboratory (JPL) puts the packets together for what is known as a “quick look”. The entire image generally has not yet been received by this point in time, but it is enough of the image that it can be processed to take a quick look at it. Subsequently, JPL puts together all of the data it has received every 4 hours and makes it available to the computers at HiROC.
5. After the files have been put together by JPL, then one of the computers at HiROC looks and sees that there is data on the JPL server and copies the data to our system at HiROC. This is the start of what is known as the pipeline, the system of programs at HiROC which process the images. This usually happens either via a direct connection to JPL (slower), or through the Internet 2(Faster, but sometimes can be bogged down).
6. The images are put together into a viewable format, using the minimum processing possible, and create what’s known as an EDR, or Experimental Data Record. This is done without calibration, stitching together the channels, or any other processing, aside from putting the image together. For an image which uses all 14 CCDs, there will be 28 EDRs. These generally speaking are of mainly scientific interest, but they will be released to the general public via the Planetary Database System (PDS). They will be in the standard PDS format.
7. After the EDRs have been created, they are converted to another format for ISIS. ISIS, the Integrated Software for Imagers and Spectrometers is a suite of tools used for processing images for most interplanetary missions, that was developed by the United States Geological Society (USGS). Most of the tools that we use at HiROC for processing our images are written for ISIS files.
8. After the ISIS files have been created, they are calibrated via a program called HiCal. This reduces the inherent noise of the camera to be more consistent with what is being photographed. All digital cameras create some level of noise, and while HiRISE is an extremely good instrument, it still generates a low level of noise.
9. After the individual channels are calibrated, then they proceed to a program called HiStitch, which puts the two channels of the same CCD together. As they are a part of the same CCD, this requires little processing.
10. Next, after each CCD been stitched together, the full CCD images run through a program called HiccdStitch. This program puts the different ccds together, making a mosaic for each color band. This requires some processing, as the ccds slightly overlap, and it can sometimes be difficult to match the different arrays exactly.
11. If the image has not been completely received, then at this point, the pipeline stops, until JPL has received the entire image, or if there are a few confirmed gaps in the image which we haven’t been able to recover. Transmission over the vast distance between Earth and Mars is not easy, and even the best systems have some small error.
12. After the image has been completely stitched together, then the image is geometrically projected. To understand this, realize that the images that HiRISE takes are flat, while Mars is actually round. Geometrical Projection alters the image so that the image points in compass directions, while correcting any distortions that are created by the ellipsoidal shape of Mars. With the geometrical projection images and the right software tools, such as qview for ISIS, the exact distance can be found between two point on the image. In order for this to happen, we must wait for information to be gathered on the exact position of the spacecraft. This is done by the nagivational team, based off of the downlink frequency. This takes two weeks after the picture has been taken, so Geometric Projection might take a while. This is the longest wait point of the operation. An image can be released from predicted information, however, most images will wait for the correct SPICE kernels to be calculated, in order to get the best information. If an image is geometrically projected from predicted information, it will be calculated with the correct info after it has been received.
13. The images are then validated by a team of students known as the HiRISE Validators. They check to make sure that everything in the pipeline worked perfectly, see if there are any gaps in the images, and other similar tasks. If they notice a problem, they contact the HiRISE Operators, who will take steps to resolve the problems, which may include passing part or all of the image through the pipeline again, or tweaking the software to make it work perfectly.
14. The image is converted to a format that the general public can use. Currently that format is JPG, or TIFF, but eventually we will use JPEG 2000.
15. After all of this, the science team members of HiRISE will look at an image to see if there is anything noteworthy. If there is, it is given a caption, and perhaps a press release. If not, it will be posted on the HiRISE website. They are also posted on the MRO website, and occasionally on others.

This process may take as long as a week or two to complete, depending on the load of MRO, scheduling concerns, load at HiROC, etc. The first image took about 9 hours to be completely processed after it was taken by HiRISE. The Victoria Crater picture, taken during a much busier time on MRO, took about 36 hours to make its way to our hands. This was in part due to the larger size of the image, as well as the cache of images already awaiting transmission on MRO to earth. The captions for the images taken during Transition imaging took anywhere from a few hours to a few weeks to write, and this will likely continue to hold. We at HiROC want to release the images we take as fast as possible to the public, and we are doing everything we can to realize this goal. Several shortcuts were taken during the Transistion imaging phase that allowed for images to be released quicker. For Primary Science Phase, this will take a bit longer because these shortcuts will not be taken, but we expect that we will release most images within two weeks after them being taken, shortly after we have finished receiving, processing, and captioning the image.

There are some variations to this process, for example, the Victoria Crater picture was released in a press conference jointly with the Mars Exploration Rovers (MER) team. Also, color images require extensive calibration and take a lot more time. However, this is the general idea. Currently the entire system, except for writing the captions and adding the images to our website, is essentially completely automatic for receiving and processing HiRISE images, due to years of preparation by the HiTECH and HiOPS teams.