What is acquisition footprint noise in seismic data?

Acquisition footprint is a noise field that appears on 3D seismic amplitude slices or horizons as an interwoven linear crosshatching parallel to the source line and receiver line directions. It is for the most part an expression of inadequate acquisition geometry, resulting in insufficient sampling of the seismic wave field (aliasing) and irregularities in the offset and azimuth distribution, particularly in the cross line direction.

Sometimes source-generated noise and incorrect processing (for example residual NMO due to erroneous velocity picks, incomplete migration, or other systematic errors) can accentuate the footprint.

This noise can interfere with the mapping of stratigraphic features and fault patterns, posing a challenge to seismic interpreters working in both exploration and development settings.

To demonstrate the relevance of the phenomenon I show below a gallery of examples from the literature of severe footprint in land data: an amplitude time slice (Figure 1a) and a vertical section (Figure 1b) from a Saudi Arabian case study, some seismic attributes (Figures 2, 3, 4, and 5), and also some modeled streamer data (Figure 6).

Bannagi combo

Figure 1. Amplitude time slice (top, time = 0.44 s) showing footprint in both inline and crossline direction, and amplitude section (bottom) highlighting the effect in the vertical direction. From Al-Bannagi et al. Copyrighted material.


Figure 2. Edge detection (Sobel filter) on the Penobscot 3D horizon (average time ~= 0.98 s) displaying N-S footprint. From Hall.


Figure 3. Edge detection (Sobel filter) on a shallow horizon (average time ~= 0.44 s)  from the F3 Netherlands 3D survey displaying E-W footprint.

Davogustto and Marfurt

Figure 4. Similarity attribute (top , time = 0.6 s), and most positive curvature (bottom, time = 1.3 s), both showing footprint. From Davogustto and Marfurt. Copyrighted material.


Figure 5. Amplitude time slice (top, time = 1.32 s) the corresponding  coherence section  (bottom) both showing footprint. From Chopra and Larsen. Copyrighted material.

Long et al

Figure 6. Acquisition footprint in the form of low fold striation due to dip streamer acquisition. From Long et al. Copyrighted material.

In my next post I will review (with more examples form literature) some strategies available to either prevent or minimize the footprint with better acquisition parameters and modeling of the stack response; I will also discuss some ways the footprint can be attenuated after the acquisition of the data (with bin regularization/interpolation, dip-steered median filters, and kx ky filters, from simple low-pass to more sophisticated ones) when the above mentioned strategies are not available, due to time/cost constraint or because the interpreter is working with legacy data.

In subsequent posts I will illustrate a workflow to model synthetic acquisition footprint using Python, and how to automatically remove it in the Fourier domain with frequency filters, and then how to remove it from real data.


Al-Bannagi et al. 2005 – Acquisition footprint suppression via the truncated SVD technique: Case studies from Saudi Arabia: The Leading Edge, SEG, 24, 832– 834.

Chopra and Larsen,  2000 – Acquisition Footprint, Its Detection and Removal: CSEG Recorder, 25 (8).

Davogusto and Martfurt, 2011 – Footprint Suppression Applied to Legacy Seismic Data Volumes: 31st Annual GCSSEPM Foundation Bob F Perkins Research Conference 2011.

F3 Netherlands open access 3D:  info on SEG Wiki

Hall, 2014 –  Sobel filtering horizons (open source Jupyter Notebook on GitHub).

Long et al., 2004 – On the issue of strike or dip streamer shooting for 3D multi-streamer acquisition: Exploration Geophysics, 35(2), 105-110.

Penobscot open access 3D:  info on SEG Wiki

NASA’s beautiful ‘Planet On Fire’ images and video

Please give credit for this item to: NASA's Goddard Space Flight Center and NASA Center for Climate Simulation Australia photo courtesy of Flagstaffotos

Credits: NASA’s Goddard Space Flight Center and NASA Center for Climate Simulation.



Click on the image to watch the original video on NASA’s Visualization Explorer site.

Read the full story on NASA’s Visualization Explorer site.

Going for the Moon


While on a flight to Denmark a couple of years ago I happened to read this interview with Swedish astronaut Christer Fuglesang. Towards the end he talks about feasibility (and proximity) of our future missions to the Moon. This subject always gest me excited. If there’s one thing I’m dying to see is a manned missions to the Moon and Mars in my lifetime (I was born in 1971, so I missed by a split hair the first Moon Landing).

I hope we do it soon Christer!

Why go back?

My personal take is that of the dreamer, the 12 years old: why go back to the Moon? Because it’s there…. I mean look at it (photo credits: my uncle, Andrea Niccoli)!!


Beautiful Moon. In evidence the Mare Crisium, and craters Cleomedes, Langrenus, and Vendelinus.

Red Moon

Beautiful red Moon.

Copernicus - Appennines

Beautiful Moon. In evidence the Sinus Iridum in the top left, the Copernicus crater in the centre of the image, and the Apenninus Montes just North of it with the Eratosthenes crater.

Gassendi - Tycho

Beautiful Moon. In evidence the Gassendi crater in the centre of the image, and the Tycho crater to the right with one of the Rays.

On a more serious note, this is what Lunar scientist Paul Spudis has to say about why we should go back:


Moon exploration resources, and educational and vintage material

Rift valleys rewrite moon’s fiery history


Moon gravity Grail

NASA’s LRO Creating Unprecedented Topographic Map of Moon

Moon composition mosaic Galileo

Recent geological activity Lunar Reconnaissance Orbiter

Fresh Crater

NASA’s Beyond Earth Solar System exploration program

We choose the Moon – Wonderful, interactive recreation of Apollo 11 Lunar Landing  – 40th Anniversary celebration

Raw Video: Restored Video of Apollo 11 Moonwalk

All Apollos’ Lunar Surface Journals

BBC – In video: When man went to the Moon

BBC –Aldrin: I was relieved to be second

Fun / idiotic stuff

Space 1999 (cheesy, but unforgotten ’70s TV show, full pilot) – Moon breaks away from Earth.

Dumb and dumber  – We landed on the moon – pure Jim Carey’s genius!!!.

Moiré Patterns

Moiré pattern

Some time ago I reblogged a post from El Ojo Inoportuno showing Moiré pattern, which resulted from taking a photo of a circular pattern of (beautiful) tiles. This phenomenon is caused by undersampling and is also called space aliasing. There’s a very good explanation of space aliasing and another stunning Moiré example on Agile Geoscience’s post N is for Nyquist.

Creating Moiré patterns

One way to get Moiré pattern is to superimpose two identical, transparent line gratings and rotate one by an angle. You can see an animation of this on Wolfram Mathworld here; notice that the pattern varies with the angle. In the same page there’s also an example of Moiré Patterns generated by plotting series of curves on a computer screen, which is very similar to taking the photo of circular tiles shown in the Ojo Inoportuno photo. Again the interference is caused by representing circles with a finite size pixel grid. If you are interested you can experiment with these effects and many more by downloading templates from this site. Figure 1 shows my own Moiré from circular patterns.


Figure 1


There is a program for interactive Moiré pattern experiments called iMoiré.

Another way to get a Moiré pattern is to scan a picture printed with halftone. There’s a simple explanation of this scanning-generated interference here. Again this is a matter of aliasing, or undersampling. Here’s a good example:

Figure 2

The original image is a lovely watercolor by  Ettore Roesler Franz showing medieval houses along the Tiber river in Rome. The Moiré Pattern results from scanning the watercolor from one of the book collections (the image was posted on Flickr here).

How to remove Moiré pattern from digital images

For a quick solution, there’s a good article with detailed instructions on how to remove Moiré pattern in Photoshop, Paint Shop Pro, etcetera. For a more advanced workflow there’s an excellent top hat filter in Photoshop included in Reindeer Graphic’s FoveaPro plugin. In Figure 3, I created a sort of pictorial chart of this workflow using low resolution copies of examples in The Image Processing Cookbook, by John C. Russ.


Figure 3


In future posts I plan to show how to remove Moire’ pattern with open source code images  using Python, and then to extend the workflow to the removal (or attenuation) of acquisition footprint in seismic data, which has a very similar appearance in the 2D Fourier domain, and can be filtered with very similar techniques.



Some photos of Northern British Columbia wildlife and geology


Last week I went  on a helicopter ride with Gerry, my father in-law, to count of Kokanee Salmon in the  Camp Creek near Valemount, BC. We were invited by Curtis Culp of Dunster, BC, which is in charge of this  conservation effort run by BC Hydro. Here’s a picture of Gerry leaving the chopper (from Yellowhead Helicopters).


Kokanee salmon is a land-locked relative of Sockeye salmon. This means that they spend all their life in inland lakes, never seeing the ocean. For spawning  they enter inlet streams of the lake where they live. Camp Creek is a smaller tributary of the Canoe River, inlet of the Kinbasket Lake, where these Kokanee live.

The number of fish is estimated visually from the helicopter using a hand-held tally counter (every ~100-fish patch is a click). As a matter of facts, Curtis and Gerry counted fish, and I went along for the fun. Their estimates were really close, coming in at 15,000 and 15,400 in ~35 minutes over a ~15 km stretch of the Camp Creek. I counted 15 between Bald eagle and Golden eagle, and took some photos. Here they are!

Wildlife and nature photos

The first two are photos looking straight down the Camp Creek. Believe it or not, there’s fish there. See the dark spots? Those are Kokanee Salmon. And the job was to count them, so I am glad I did not have to (although it was easier to the naked eye).



The next two are a couple of photos taken at the ground level, courtesy of Curtis. Here the salmon is easy to see.

Kokanee ground

Kokanee ground1

The next two are also photos of the creek from the helicopter. There’s fish in there but I can only say it because I saw them, I can’t quite make them up in the photos. I love the shots though, the crystal clear water and the shadows.



The following two are photos with eagles. I could not believe how tiny they look, since even at this distance they seemed huge to the naked eye. There is a bald eagle in the first photo (middle left) , the other two (in the middle of the second photo) are too tiny, it is hard to say.



This last one is a photo of the trees, just looking down. I find it mesmerizing.trees

Upon looking at all the photos (I took about 80) I have to say that as much as I love my iPhone 4S, they are not nearly as good as I had wished for. Certainly far from the photos I shot during a claim staking trip in the Cassiar Mountains near Watson Lake, Yukon using a Canon FTb 35 mm (one of these days I’ll have to get those photos out of the attic and publish some of them). I often think of going back to my reflex camera, although I hear the iPhone 5 camera is a big improvement, with the iPhone 5S being even faster, so there’s hope.

Bonus photo

Here’s a beautiful elk. I took it another day, on the highway just outside of Jasper, but I thought it would fit in here.


Geology photos

I love meander rivers so I took a whole lot of photos of the creek. The first one shows a nice sandbar right where we started the counting.


This next one is a nice shot of the meandering creek looking back.

Camp Creek

In this third one you can see two nicely developed meander loops with point bars.


Last, but not least, a really tight meander. I love this photo, it’s my overall favourite.


Human activity photos

I am also including some photos showing the human footprint on the land. This first one is a clearing – I am not certain for what purpose, likely a new development. The circular patches are places where the logs were collected and burned. Quite the footprint, seen from here.


Next is something I did not expect to see here, a golf course – although I probably should have…. they are omnipresent, and often obnoxious, to say the least.


This is one I quite like: the creek, the railway, and the Yellowhead highway, all running next to one another.


The team

Finally, a shot of Gerry and I in the back of the chopper and one of Gerry counting.



Geology photo quiz #1

Take a look at the photo below, which I took it on the way up to McBride Peak (in McBride, British Columbia). It is a view up the Sunbeam Creek, part of an Ecological Reserve. Question: why would (only) part of the creek be so white? My father-in-law and I had been wondering since a previous hike to the top of the Peak, and speculations were running rampant. Finally, yesterday, we decided to hike up to the top again, then go down to the creek to find out. I think we did, and it was a great hike and a lot of fun. I am in the process of writing a nice post on this geo-adventure, but I though in the meantime I’d post the photo and make it a quiz.


I will give readers two clues:

1) the mysterious white “stuff” sits in a creek where water is actually running;

2) this is a south face, exposed to the sun all day long, so it couldn’t be snow or ice.

Below is a close-up photo. So, what do you think it is?
Or at least, what do you think it could be?



I love this photo (thanks to Carlos Mario del Rio for posting it)!
There’s something about tiled floors (and tiles in general) that has always mesmerized me and this is a really good one. I like the unusual perspective too.
There’s a radial pattern and a circular pattern of tiles, but if I stare at the photo I also see hints of an interference pattern, an intriguing flower pattern. I think this is a genuine Moiré pattern, one quite well known to photographers, generated by interference between circles of varying distance with the camera’s sensor pixel grid.
In my next post I will look in more detail at Moiré patterns and try to explain how they form.
I will show how the effect can be removed, or at least reduced, particularly from scanned images. Similar techniques can be used to remove acquisition footprint from reflection seismic data, which will be the topic of an upcoming series on MyCarta.