A 5.7 Terapixel Mosaic of the Surface of Mars | Hacker News Reader

A 5.7 Terapixel Mosaic of the Surface of Mars

murray-lab.caltech.edu

219 pointsmpweiher63 comments

Perseverance's path puzzled me. The good thing is that NASA has an up-to-date map [0] of its path, also joined by lines, which shows more of the path and also confirms how odd some stretches of its voyage have been.

Does anyone know why it spent so much time going back and forth?

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Edit: I see, it was always going back to the "Sample Depot Zone" to deposit the collected samples. This zone is where the chaos begins after the very long stretch. Here's [1] more info on the depot, including a photo made by the rover of what such a deposited sample looks like.

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[0] https://mars.nasa.gov/mars2020/mission/where-is-the-rover/

[1] https://www.nasa.gov/feature/jpl/nasa-s-perseverance-rover-c...

Actual site: https://murray-lab.caltech.edu/CTX/

Wow that 3D viewer is smooth on mobile phone. So amazing to pinch and scroll around the planet.

Are there photos anywhere? The 3D viewer's just showing black for me. (Viewer itself loaded, but as though no data specified/loaded - except what I assume are different views to jump to listed at the bottom.)

Downloadable dataset here: https://murray-lab.caltech.edu/CTX/V01/tiles/

Please do not hammer the service unnecessarily, it's nice that they offer this publicly so lets not ruin the commons here.

wow a lot of big files, maybe they should publish it over WebTorrent

It's quite amazing and simultaneously ridiculous that we have a public 3D model of a distant planet at 5 meters resolution while the best available free and public models of Earth are at 30 meters.

You can fly your satellites lower in mars due to atmosphere density, as low as 20km it appears

On top of that isn't the lower resolution on earth more for military reasons than a technical one or is this not the case any more?

Hasn't been really the case since french airbus started offering highres global imagery. If you have deep pockets, you can buy 30cm/px (i.e. order of magnitude better than this Mars dataset) images of pretty much anything.

I wonder if there's any sources for those images that aren't cough restricted. Could be interesting to play with, though maybe not worth paying for.

What do you mean, there are many resources that provide access to various satellite images. In general satellite imaging is not really that sort of hushhush industry it maybe was 50 years ago.

I read parent as looking for sources that provide access to hi-res satellite imaging, without them needing to provide access to their wallet.

I think the thread is referring to satellite pictures of more sensitive locations (like military bases, gov facilities, etc)

But I can imagine it all depends on jurisdiction. A Russian or Chinese satellite imagery company will have no problem publishing clear images of US military bases, while an American satellite company may have to comply with US laws prohibiting that.

And vice versa.

Ultimately if you cobble together imagery from multiple sources, you can probably get everything you want.

And presumably the atmospheric distortion is much less as well.

it's surface area also a lot smaller

However, the total surface area of Mars is roughly equal to the total land area of Earth.

If I wanted to make a textured globe, you just made my oceans totally smooth. Some of the tallest mountain ranges we have are in the area you just nulled out.

And how exactly would satellite imagery (no matter which wavelength range) help you texture the ocean floor in your globe?

nobody said optical wavelengths were the only meaning of imagery.

Turns out the surface of the ocean has ridges and valleys that match the seafloor, and these can be measured by radar from a satelite

Atmospheric distortion looking down is not as severe as it is looking up. This is because the distortion subtends much greater angles looking up than looking down, since the distortion is close to the observer. Looking down, it’s also true that, at least in daytime, exposures are very short as well by virtue of the earth being very bright.

Well yes, but we certainly have better resolution imagery of Earth for many places. It's just that the Mars data is free and the Earth data is owned by corporations that sell access to it for a lot of money.

WorldView-3 claims to be 31cm resolution: https://worldview3.digitalglobe.com/

Not public. I don't even see a pricing page, so can assume very pricey.

Also this is appears to be the optical resolution, unrelated to an elevation model.

All major imagining satellites provide stereo imaging suitable for 3d reconstruction. Airbus has whole suite of products around this, and probably the biggest reason why there isn't off-the-shelf products for WV3 is because its just so new.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7248834/

https://www.intelligence-airbusds.com/imagery/reference-laye...

Afaik in the ballpark of $500/25km² for archive images.

It’s easier to cleanup someone else’s house.

Doesn't google earth use 1 meter resolution in certain areas?

Isn't that data from airplanes and not satellites?

Airplane data would be below 30 cm resolution.

"Free to access" in highly limited ToS is not free in a reasonable way when it comes to data.

Huh? Did you intend to respond to a different comment?

We actually don't have a 5 meter global elevation for Mars. The imagery is 5 mpp but the elevation data used in the links is MOLA and is closer to 500 meters per pixel (with another merged product at 200 mpp). It is almost more weird/cool that we have hundreds (thousands?) of 1 mpp elevation models for small areas of Mars from HiRISE (available for free from the PDS) and larger swaths at ~20 meters per pixel from CTX imagery used in this global mosaic, but still not close to a global product.

various sources: 1. https://astrogeology.usgs.gov/search/details/Mars/GlobalSurv... 2. https://astrogeology.usgs.gov/search/map/Mars/Topography/HRS... 3. https://www.uahirise.org/dtm/ 4. https://stac.astrogeology.usgs.gov/docs/data/mars/ctxdtms/

Abolutely stunning that you can hand your child a tablet and let them browse a google earth style depiction of another planet in such detail. Inspiring.

This was published two months ago but didn't get much attention:

https://news.ycombinator.com/item?id=35501337

https://www.nasa.gov/feature/jpl/new-interactive-mosaic-uses...

For comparison, Earth including water surfaces at one meter resolution would be 510 Tpx.

For anyone who studies Martian geology: What is the deal with the 5km deep gorge extending for 1000's of km around -70.654932°‎, -11.473828°‎?

It looks like the planet was almost torn in half.

(Turn on "MOLA Topography"-layer to see it)

it's valles marineris https://en.wikipedia.org/wiki/Valles_Marineris

The largest feature on Mars is so vast that it isn't normally visible: the Northern hemisphere is quite a bit lower than the Southern (1 to 3 km):

https://en.wikipedia.org/wiki/Martian_dichotomy

Edit: Very obvious in Google Maps Mars:

https://www.google.com/mars/

Wow. This is the most inspiring thing I've seen since the video of two boosters landing side by side.

Many years ago, X-Plane version 8 or 9 included Mars scenery. This would make for a nice upgrade of that. The scenery was a bit lacking in detail and the atmosphere and gravity were of course adjusted. Pretty hard to fly there because the atmosphere is very thin.

So, basically, you need some kind of rocket plane that flies at insane speeds. Makes for interesting take offs and landings.

There is currently a propeller driven VTOL aircraft operating on Mars.

The thin atmosphere definitely poses some challenges, but those are offset a little by the lower gravity. It's not easy, but it can definitely be done (as Ingenuity as shown)

watching natgeo and discovery science shows (before they went to shit) years ago, i remember one time the narrator was saying something like "in future, nasa plans to fly unmanned unattended drones which will automatically decide the flight plan and navigation and collision avoidance because the roundtrip communication with earth is at best 20 minutes so it would be unfeasible to fly-by-wire from earth.

at the time, it was genuinely sci-fi that we can send a small airplane to mars and have it zip across the skies there without human intervention and today that is already history. wow.

Or much bigger wings. Pretty viable given the gravity.

The face is located at 40.747484°‎N, 009.462645°‎W

If this was released by google, they'd just blur it out

Thanks, I was about to ask, good thing I searched first!

I'd like to buy a mars globe with a nice up-to-date high-res print of the surface.

The globes i have seen are expensive and have outdated maps.

Sphinx on Mars

Does anyone know the more precise coordinates for the Sphinx on Mars that 40.75, 9.46?

https://en.wikipedia.org/wiki/Cydonia_(Mars)

Switch to "DD" coordinate mode and go to 40.7456°N, 9.4621°W.

For a sec I thought I was about to hear Deckard say "Gimme a hard copy right there."

So each pixel is about 5m x 5m? With Mars having a surface area of about 145 million square km, or 145 trillion square metres

Correct.

Makes me wish we had a 5x5 model of the earth. The only really freely available terrain data set is 30x30 for the world and there is the 25x25 DEM for Europe by Copernicus.

That's spectacular. I'm curious how much storage space the entire dataset consumes in it's compresed form?

> The mosaic images are stored in zip files that reduce the download size. The entire mosaic (compressed) is 5.6 TB, including seam maps but not including overviews for the GeoTiff files. Unzipped and uncompressed, the entire mosaic is 11.484 TB, including overviews.

Genuinely amazing piece of technology, this is so cool

and still black and white

Url changed from https://kottke.org/23/06/a-massive-57-terapixel-mosaic-of-th..., which points to this.

>5.0 m/px

How does that compare to , e.g. aerial photography resolution or some familiar standard ?

Edit: ChatGPT gave me:

  .28 cm/px for a studio portrait photo (factor 2000x)
  8.3 cm/px for a landscape photo (factor 60x)
  30-200 cm/px for aerial photos (factor 2-20x)

Commercial satellites imaging Earth can do about 30cm/px (or .3m/px), conventional aerial photos are afaik in the ballpark of 5cm/px, drones can do <1cm/px

The special thing about this Murray mosaic is that it seamless continuous image across the whole Mars surface, they spent lot of time gluing and stitching the raw images together. Furthermore, important for science, each pixel can afaik be traced back to specific capture, so there is provenance.

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