Advances in LRO-NAC processing in ASP

Since I last wrote, we’ve hired a new full-time employee. His name is Scott and we assigned him the task of learning ASP and LROC. The first utilities he’ll be contributing back to ASP are lronacjitreg and lronac2mosaic.py. The first utility is very similar to the ISIS utility with a similar name designed for HiRISE. The second utility, lronac2mosaic.py, uses the first tool and can take LRO-NAC EDR imagery and make a non-projected image mosaic. What lronac2mosaic.py does internally is ‘noproj’ and then ‘handmos’ the images together. There is an offset between the images due to model imperfections. Finding the correct offset so the combined images are seamless is the task of lronacjitreg. All of this just a streamed line version of what I wrote in a past blog post.

Previously users and our team only had the option to run all 4 combinations of the 4 LRO-NAC input files through ASP and then glue them together afterwards. Now with the use of lronac2mosaic, we can feed whole LRO-NAC observations into ASP and receive the full DTM in one go. No messy mosaicking of 4 files.

I’ve used Scott’s program successfully to recreate most DTMs that ASU has made via SOCET SET. Using my home server, I’ve been able to recreate 77 of their DTMs to date. We’ve been fixing bugs as we hit them. One of the biggest was in our search range guessing code. The next upcoming release of ASP will have the fruits of that labor. Previously ASP had a bad habit of ignoring elevation maximas in the image as it thought those IP measurements were noise. Now we should have a better track record of getting measurements for the entire image.

One of the major criticisms I’m expecting from the large dump of LRO-NAC DTMs we expect to deliver next year is what is the quality of the placement of our DTMs in comparison to LOLA. Another engineer we have on staff, Oleg, has just the solution for this. He has developed an iterative closest point (ICP) program called pc_align which will be in the next release. This is built on top of ETHZ Autonomous System Lab’s libpointmatcher and has the ability to take DTMs and align them to other DTMs or LIDAR data. This enables us to create well-aligned products that have height values agreeing within tens of meters with LOLA. Our rough testing shows us having a CE90 of 4 meters against LOLA after performing our corrections.

We’re not ready for the big production run yet. One problem still plaguing our process is that we can see the CCD boundaries in our output DTMs. We believe most of this problem is due to the fact that the angle between line of sight of the left and right CCDs changes with every observation. ISIS however only has one number programmed into it, the number provided by the FK. Scott is actively developing an automated system to determine this angle and to make a custom FK for every LRO-NAC observation. The second problem we’re tracking is that areas of high slope are missing from our DEMs. This is partially because we didn’t use Bayes EM for our test runs but it also seems like our disparity filtering is overly aggressive or just wrong. We’ll get on to that. That’s all for now!

Automatic Production of HiRISE DEMs 4

Server is still running. ASP has changed during this run. We introduced a new IP filtering technique, MPI Parabola was sped up, and added a faster point2dem. I don’t remember when these changes happened to my server while processing these images. I also added a timeout for stereo pairs that take longer than 3 days to process. This is to stop a bad pair from just dominating the machine for 2 weeks. During this run, I also changed the settings so that two stereo pairs are always being processed at the same time. This is to keep my CPU pegged.

HiRISE Processing Log
Left Image Time What Happened
ESP_011543_1665 N/A Timed out
ESP_011563_2200 Lost Too narrow search
ESP_011582_1730 Lost Too narrow search
ESP_011592_1595 1d 10h I dunno
ESP_011608_1525 3h Too narrow search
ESP_011661_1410 N/A Timed out
ESP_011662_1750 1d 5h Pretty good
ESP_011672_1395 1d 12h Awesome
ESP_011675_1470 20h Too narrow search
ESP_011676_1700 1d 10h Awesome
ESP_011677_1655 2h Too narrow search
ESP_011683_1540 2d I dunno
ESP_011688_1760 N/A Timed out
ESP_011701_1790 11h Okay
ESP_011715_1800 15h Pretty good
ESP_011717_1910 2d 12h Pretty good
ESP_011720_1835 21h I dunno
ESP_011722_1460 N/A Timed out
ESP_011728_0985 N/A Timed out
ESP_011740_1830 1d 7h Too narrow search
ESP_011743_1725 5h Pretty good
ESP_011761_1485 13h Too narrow search
ESP_011765_1780 N/A Failed to download
ESP_011767_1640 4h Pretty good
ESP_011772_1790 2h Too narrow search
ESP_011773_1460 21h Bad search range
ESP_011780_1515 7h Awesome
ESP_011785_1875 4h Too narrow search
ESP_011818_1505 2h Awesome

Images