
Sensors of largest digital camera snap first 3,200-megapixel images at SLAC - dfee
https://www6.slac.stanford.edu/news/2020-09-08-sensors-world-largest-digital-camera-snap-first-3200-megapixel-images-slac.aspx
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neltnerb
"their resolution is so high that you could see a golf ball from about 15
miles away."

Okay, that's just a nerd swipe. What's the field of view! Oh journalism...

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cl3misch
Edit: Below is incorrect. They claim the _total area_ is enough to capture 40
full moons, not that the sensor is 40 full moons across. Assuming a perfectly
round sensor you could estimate its radius from that, but that's too much on
my phone.

Maybe they "left it as an exercise for the reader"? ;-)

The FOV is "40 full moons", so 40•0.5° = 20°. For a plane 15 miles away that
comes to an image covering 2•15•tan(10°) miles = 5.3 miles.

So you can spot a golfball on an image that's 5.3 miles large.

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idlewan
On one of their picture, it shows 7 moons wide, which is probably a good
approximation (6 lines of those 7 moon images does seem close to filling the
area of the sensor in their pictured representation, if you then shift some
moons when the sensor lines get shorter at the top and bottom).

So using your calculation it could be, approximately: 7*0.5° = 3.5° in FOV.

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ehsankia
What's the point of putting a highly detailed Romanesco broccoli under the
lens for testing if the results is going to be a blurry mess?
[https://www.slac.stanford.edu/~tonyj/osd/public/romanesco.ht...](https://www.slac.stanford.edu/~tonyj/osd/public/romanesco.html)

What's the point of even posting that. What were they testing? Is this an
issue with focusing on things that are close?

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throwaway56034
The article has the answer to your question: There was no lens, just a
pinhole. The lens and filter system gets integrated "over the next few
months". They tested the sensor array, not the lens.

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throwaway8451
Ha, that's how I tested a DSLR that I had repaired. There was no matching
objective there, so I wrapped aluminium foil over the front and, using a
needle, stabbed a tiny hole into it. The pinhole setup was good enough to test
what I needed to test :D

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ideals
Their flickr album has a bunch of pictures. Highly recommended, really awesome
images!

[https://www.flickr.com/photos/slaclab/albums/721577137971034...](https://www.flickr.com/photos/slaclab/albums/72157713797103466)

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sandworm101
It is an array, not really a single camera. Note that there will be dead
space, black lines between sensors, that wouldnt be acceptable in any camera
not meant for a telescope. Imho if we are going to talk about big cameras, the
detector array is less important than the light gathering system of mirrors
and lenses.

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brudgers
A digital sensor is an array of pixels. There are lines between
pixels...assuming no AA filter, in which case there are lines between filter
cells. The objection is a “No true Scotsman.” A camera consists of an aperture
for collecting light and a medium for observing the collected light, e.g. the
cameras obscura and lucida. If the collecting medium can record the collected
light, it can produce photographs, either still or moving.

It’s worth noting that astronomical pictures often consist of multiple
overlapping photographs. And I guess it’s plausible to describe a digital
sensor as capturing many one pixel photographs.

~~~
formerly_proven
Microlens arrays have been standard for years and increase the fill factor to
~100 %, so the argument is kinda bogus. In any case, the gaps between adjacent
sensors in a "raft" are much bigger than the pixel pitch, and the gaps between
rafts again larger, so the argument is kinda moot either way.

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4ad
Who cares about a bunch of digital sensors stitched together. What's more
interesting is the optical assembly:
[https://www.llnl.gov/news/world’s-largest-optical-lens-
shipp...](https://www.llnl.gov/news/world’s-largest-optical-lens-shipped-slac)

Anybody got real technical information about that?

Edit found it:
[https://www.lsst.org/scientists/keynumbers](https://www.lsst.org/scientists/keynumbers)

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TheSpiceIsLife
> the camera will collect images of about 20 billion galaxies

If there were intelligent like out there advertising it's presence, are we
likely to detect it given the sheer quantity of sources?

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dewitt
> If there were intelligent like out there advertising it's presence, are we
> likely to detect it given the sheer quantity of sources?

Humans are pretty intelligent. Intelligent enough to ask that question,
anyway.

So flip it around. If humans were to advertise our own presence to possible
species living tens of billions of light years away, how would we go about
doing it?

Sadly, even if they noticed and wrote back, our sun will have since burned
out, our time in this universe long past.

~~~
RantyDave
I, also, have wondered this and came to the conclusion that you use whatever
medium travels faster than light. Because until we discover that we're totally
isolated anyway.

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jonplackett
How does it deal with the gaps between the sensors? How come that doesn’t
create lines in the images?

~~~
de_Selby
The same reason you can see perfectly out of sunglasses with mesh lenses -
basically light behaves like a wave so small gaps have little to no effect.

~~~
nullc
uh. are they doing some kind of bizarre imaging with micro-lenses at the array
and offsetting the focal plain? -- because otherwise it doesn't. Gaps are
missing pixels.

Presumably for astronomical applications they don't matter.

~~~
kellenmurphy
Usually it's gotten around because astronomical images are stacks of many
integrations, and then you dither around. If you take 10 5-minute exposures,
for example, and you dither around correctly, you might have a bunch of pixels
with 9/10 or 8/10 data values... then you stack the images and weight those
pixels accordingly.

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leeoniya
somewhat related (2013): [https://www.pcmag.com/news/10-jaw-dropping-
gigapixel-photos](https://www.pcmag.com/news/10-jaw-dropping-gigapixel-photos)

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mensetmanusman
Is there a constellation pattern SpaceX could use that would leave open a
clear sky above Chile? (Maybe at the expense of not offering service in the
country).

~~~
tgb
Any orbit has to cross the equator, so anything that avoids Chile is also
going to have to avoid quite a lot of other stuff. Only a geosynchronous orbit
would make any sense there and then it'd be too high to have low latency.

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01100011
Has anyone ever taken the tour of SLAC? It's currently unavailable due to
COVID-19, but it's on my Bay Area bucket list.

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dsign
How does one applies filters and other algorithms to images so large?

~~~
formerly_proven
In terms of throughput, not a problem at all. With proper GPU computing
techniques you can do full color correction and so on at dozens of Gigapixels
per second on a single desktop GPU (bound by memory bandwidth).

The problem is more with bandwidth and working memory. For example, if you'd
stream the image to a GPU (at 6.4 GB per image, assuming it's greyscale 16
bit), you're just being bottlenecked by PCIe plain and simple. GPU memory
sizes aren't favorable to these sizes, either, most models don't have enough
memory to have one input and one output buffer (assuming you also want 16 bit
out). So, with a single GPU the bus would limit you to around 1-2 pictures per
second.

However, the quoted throughput is "30 TB per night", that's only one GB per
second. So it's plausible (but unlikely they do) to process all of the data on
a single desktop PC with a GPU and a dual 10 GbE NIC card.

~~~
londons_explore
It's plausible to run a _lot_ of webservices in a single machine.

It's hard to engineer right and doesn't scale, so people rarely do it...

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hellified
Why do I have the feeling this camera will fit in a phone in 3 years?

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Galaxeblaffer
Because you don't know anything about how camera sensors work ?

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MontagFTB
Please try to make HN a corner of the web where participating benefits
everyone. Perhaps a breakdown or rationale as to why a camera sensor of this
resolution will never be that small?

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guerby
Submitted the exact same URL two days ago, isn't HN supposed to merge same
URLs discussions?

[https://news.ycombinator.com/item?id=24431211](https://news.ycombinator.com/item?id=24431211)

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iso947
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