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Comment by frabert | Hacker News Reader

Just an observation: 1mm pitch is awful.

Always? If I'm standing 10 metres away, I don't think it would be too bad. Even at 1 metre away it would be fine.

With images as large as the OP is talking about, at typical viewing distances pitch substantially larger than 1mm would be just fine.

Yes, 0.1mm would be much better, that's 254 DPI. You'd also want 24 bits (3 bytes) per pixel instead of 1 bit. That gives you 0.43x0.43 miles, which is still mighty impressive.

a follow up thought experiment:

how long to walk that distance, VS how long to read the image from the SD card......

answer:

walking the perimeter (aprox 2 miles): aprox 30min

reading 1tb (assuming sustained speed of 20mb/sec): 14.5hrs

next: consider WRITE speed...

> Of the two cards, Western Digital is claiming a performance advantage by citing up to 160MB/s read speed

so, 1h 44 minutes, which is not that bad

That is assuredly their best-case-scenario "burst" speed.

The sd cards I have always list some performance like "up to 80mb/sec" but never seem to get close in reality.

I agree with you that 3/762 of an inch would be much better pitch, as that works out to be around 700 x 700 metres ( 49 hectares).

Or head towards 72 DPI and get document quality resolution over a square mile.

72 DPI, document quality?

Ahh, the days before "retina displays", yes.

;-)

72 DPI hasn't been current since well before retina displays, you might have to go all the way back to the original Macintosh. Even an old 14" 1024x768 display was 91 DPI.

Awful for what?

When intuitively visualising the number of pixels in a terrabyte I think it's quite good.

When you're trying to leverage your intuitive understanding of photos, using such a low DPI will screw up that intuition and damage the accuracy. 1mm black and white is basically a QR code.

I prefer to visualize things at a reasonable density. Using boring software and a boring printer, adding in redundancy and still using very visible dots[1], you can fit over 7000 bits per square cm instead of 100.

That old 2MB card turns out to only be worth 4 sheets of paper. 1TB remains enormous, but going from 3 square miles down to .1 square kilometers helps to bring things closer to understandable. With this new density it's 25 acres or 17 football fields.

Considering the flash layers is also useful to my intuition. That old CF card is four pieces of paper next to each other. This new card is a box 32 meters / 105 feet on each side, filled edge to edge with densely printed dots on paper stacked 96 sheets deep. I can actually visualize that room / yard. I can visualize the dots on a sheet of paper. I cannot visualize a square mile at human scale.

[1] http://www.extremetech.com/wp-content/uploads/2012/08/extrem...

I was thinking purely about the physical size of a single bit. I feel like I can personally interact with a 1mm object. Anything smaller gets in the way of the physical intuition. I wasn't actually thinking about photos at all.

Anyway, thanks for your perspective! I think the conclusion is the same -- we've come a long way from the internal combution engine.

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