Orchid XP v8 wrote:
>>> Doesn't appear to be very accurate though... (And that's only for 
>>> objects with trivial geometry.)
>>
>> Well, it *is* a doctoral thesis. Wait till it gets productized. You're 
>> seeing a proof of concept here.
> 
> LOL. Is "productized" even a word?

It is in my country, yes.

> Anyway, you're acting like once you can turn a pair of images into a 
> grainy, vaguely-correct 3D model, it will then be a "trivial" task to 
> turn this into something that actually works properly. I'm not sure it is.

I imagine one could not too difficultly add code that would help the 
software figure out what it needs to see to be correct. It'll certainly be 
easier to start with the almost-right model than to start from scratch.

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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> I imagine one could not too difficultly add code that would help the 
> software figure out what it needs to see to be correct. It'll certainly be 
> easier to start with the almost-right model than to start from scratch.

Even if it can't get it 100% correct, it would be great for very quickly 
getting a 95% correct mesh done (with textures!), that only requires a bit 
of tidying up in a modeller knowing that the overall dimensions and 
proportions are correct.

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>> I imagine one could not too difficultly add code that would help the 
>> software figure out what it needs to see to be correct. It'll 
>> certainly be easier to start with the almost-right model than to start 
>> from scratch.
> 
> Even if it can't get it 100% correct, it would be great for very quickly 
> getting a 95% correct mesh done (with textures!), that only requires a 
> bit of tidying up in a modeller knowing that the overall dimensions and 
> proportions are correct.

I guess I was hoping for a system that would take a pair of photos and 
reproduce the blades of the grass, or the bumpmap of the grain in the 
wood, or the individual sugar grains in a sugar jar, or similar. You 
know, like the human eye can. The demo here seems very far from this level.

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> I guess I was hoping for a system that would take a pair of photos and 
> reproduce the blades of the grass, or the bumpmap of the grain in the 
> wood, or the individual sugar grains in a sugar jar, or similar. You know, 
> like the human eye can.

That's impossible from two photos, you may *think* your eyes can do this 
perfectly, but a lot of it is just your brain making stuff up based on what 
it is expecting to be there.

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>> I guess I was hoping for a system that would take a pair of photos and 
>> reproduce the blades of the grass, or the bumpmap of the grain in the 
>> wood, or the individual sugar grains in a sugar jar, or similar. You 
>> know, like the human eye can.
> 
> That's impossible from two photos, you may *think* your eyes can do this 
> perfectly, but a lot of it is just your brain making stuff up based on 
> what it is expecting to be there.

Wouldn't it depend on the resolution of the images and the size of the 
objects in question?

You can't make out sand grains on the brach from 4 miles out to sea, but 
I'm damned well sure you can when you're laying in the sand reading a 
book. :-P

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> Wouldn't it depend on the resolution of the images and the size of the 
> objects in question?

No, it's a simple fact that with only two photos there is never enough 
information to make a 3D model and be sure it is correct.  Your brain always 
has to add in unseen or assumed details, which most of the time are 
believably correct, but I guess this is extremely hard for a computer to do 
(as it's based on your experiences etc).

Using your grass example, I'm sure lots of blades will be hidden by others 
in the view from one eye, but plainly visible in the view from the other 
eye - how can a computer know what to do with that?  Even if the computer 
could somehow match up individual blades of grass between the two images, 
the partially hidden ones it would just have to guess where they were within 
a certain range of positions.

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>> Wouldn't it depend on the resolution of the images and the size of the 
>> objects in question?
> 
> No, it's a simple fact that with only two photos there is never enough 
> information to make a 3D model

I don't think that's true.

> and be sure it is correct.

Oh, right. That's slightly different.

> Your brain 
> always has to add in unseen or assumed details, which most of the time 
> are believably correct, but I guess this is extremely hard for a 
> computer to do (as it's based on your experiences etc).

I think the primary thing that stereoscopic vision gives you is depth 
perception. Using it, you can tell, with reasonable accuracy, how far 
away a given surface is. (Seems to be more accurate for near objects; 
very distant ones like clouds tend to look "flat".)

I would have thought it ought to be possible to take a stereo photograph 
and construct a kind of texture-mapped height field from that. I agree 
that if you take a picture of a cup, the computer doesn't really stand a 
chance of figuring out what the *back* of the cup looks like.

Now, if you take lots of pictures from lots of different angles... well, 
I'm guessing the hard part is going to be figuring out how the images 
"fix together".

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On 11/30/2009 5:28 AM, Invisible wrote:
> I think the primary thing that stereoscopic vision gives you is depth
> perception. Using it, you can tell, with reasonable accuracy, how far
> away a given surface is. (Seems to be more accurate for near objects;
> very distant ones like clouds tend to look "flat".)

Stereoscopic vision allows you to triangulate an object's position, just 
like a surveyor can determine an object's position by forming a triangle 
between an object and two reference points.

--
Michael Horvath
mik### [at] gmailcom
http://isometricland.com

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I thought this video was fitting:

http://www.youtube.com/watch?v=3609OtM138c

He talks about "one day" people being able to create 3D models from all 
the pics lying around the net of him. I guess that day has finally come 
true!!

:)


--
Michael Horvath
mik### [at] gmailcom
http://isometricland.com

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SharkD wrote:

> He talks about "one day" people being able to create 3D models from all 
> the pics lying around the net of him. I guess that day has finally come 
> true!!
> 
> :)

For some reason, the first thought that popped into my head was "OMG - 
the goatse guy! NOOOOOO!!!"

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