Messages

1

Face and Body Scanning / Re: More megapixels or better optics?

« on: April 11, 2015, 04:38:40 AM »

The needs for clothing modelling is quite different from what most people on this site seems to be doing. I only need the mesh, and only of half the body at a time. I can do lower body in one shoot, and upper body in another. I don't need texture, or any of the difficult parts, face, hair or the hands.

But the mesh must be pretty accurate for dimensions, that is the important part. It would be great if the waist and should circumferences were accurate to 1/2 inch, for instance.

On an extremely small budget, would it be better to go for structured light with 4 XGA projectors and 8 cameras, rather than trying to cobble together an array of 12-20 point-and-shoot Powershots, albeit with a painted body grid?

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Face and Body Scanning / Re: Minimum number of cameras for human body?

« on: April 11, 2015, 04:35:12 AM »

Oops, wrong (old) thread...

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Face and Body Scanning / Re: More megapixels or better optics?

« on: April 11, 2015, 04:07:39 AM »

I bump my old thread, because I have still not made a 3D scanner. I forgot about it for a while, but I still want to do it. Thanks for all the replies.

When you say it helps with projecting noise, would it similarly help to simply draw, with paint, a mesh directly on to the person being scanned, or on a tight fitting clothes? The purpose is so that I don't have to buy a bunch of projectors; I do not need any texture, only the mesh, and this will not be a professional setting at all so painting the body is no problem.

So I wonder, is there any advantage to using a projector instead of paint? Only projecting a single noise image will not be like a structured light scanner.

4

Face and Body Scanning / Re: More megapixels or better optics?

« on: June 27, 2014, 07:13:25 PM »

Thanks, looking forward to comparison.

Could you also upload comparisons between the cameras when it comes to mesh accuracy and not texture quality and colors?

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Face and Body Scanning / Re: More megapixels or better optics?

« on: June 27, 2014, 06:24:26 AM »

Ok, but I'm on a very very limited budget. And I do not really need the textures anyway, I'm only going for an accurate (measurement-wise) 3D model of the human body. Perhaps I should have linked to my original thread, didn't think about that.

Is the better optics in order to get better textures, or do they have an effect on the mesh as well? My gut feeling would be the opposite, that higher megapixels are more important for mesh accuracy, and that any lens distortion would be corrected automatically by the PhotoScan process.

I don't have the money for a bunch of DLSRs. The Canon G7, G8, etc are the higher end PowerShots that look a bit like DLSRs but are really "point-and-shoot-ish" with fixed lenses. However, they are supposed to have better quality optics than the regular consumer PowerShots.

So, I'm looking to buy used cameras, and will probably end up with a bunch of different models (all Canon Powershots though). I realize that is a hassle but I can think I can handle it.

Again, the A2500 was only an example of the type of camera I mean. I will buy what I can find as long as it seems good enough.

6

Face and Body Scanning / Re: More megapixels or better optics?

« on: June 24, 2014, 09:58:03 PM »

Nobody has any hints on whether higher megapixels or more expensive optics matter more in photogrammetry? I think in regular photography, better optics wins, but my intuition says megapixels are more important for scanning.

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Face and Body Scanning / Re: More megapixels or better optics?

« on: June 23, 2014, 07:02:25 PM »

Can't you give me some hints?

I have tried with a single camera and multiple shots, a 14 mp Casio compact that unfortunately does not do raw. What I learned was that you need good lighting, low ISO, a solid ball-joint stand, and a remote trigger. I also learned that even sharp images are surprisingly grainy when you zoom 100%.

Anyway, I can't use a single camera because I want to capture a living human being.

Having read many many threads on this forum, it seems that going for 40+ DSLR's is the best option, but I simply do not have that amount of money to spend on this. Canon compacts with CHDK seems like a workable solution for "hobby project" standards.

That is why I mentioned specifically the A2500, because it seems like one of the reasonable choices.

Again, this is just the due diligence, which of course I did.

So the above is not directly related to my question. My question is simply, if I have a choice between ~10 pieces of 12+ mp resolution compact Canons, or ~10 older prosumer ~7mp Canon ~G7's with supposedly superior optics but much lower megapixel count, which one should I go for?

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Face and Body Scanning / More megapixels or better optics?

« on: June 23, 2014, 05:42:15 AM »

I'm still trying to put together a cheap "hobby" rig.

Should I go for cheap lower end compacts (like A2500) around 12MP, or am I better of looking for used older "prosumer" devices like the PowerShot G series? The G7 and SX40 are around 6 MP I believe, and can be had at similar prices as clearance compacts.

From old online reviews of "prosumer" cameras, the pictures up close actually look about as noisy as my old 5MP Pentax Optio 550 compact camera.

But then I don't really know anything about photography and have only limited experience with PhotoScan.

9

Face and Body Scanning / Re: Multi Camera Solutions

« on: May 22, 2014, 11:03:09 PM »

I am not aware of any solution, but I have spent some time looking if it was possible, and it seems that the answer is a resounding no (for the time being, in 2014).

The resolution and image quality of contemporary web cameras is much too low. The sensors tend to have the same resolution as the video resolution (so even as low as 640x480 is not uncommon for cheaper models) and use software interpolation for the still pictures. That does not lend itself well to photogrammetry.

Webcams also lack mechanical shutters, which further destroys image quality.

I will admit though, that I have not tried it myself, because I got disappointing results from a 30-image set from a 5MP compact Pentax on a stand. My 1280x1024 webcam gives horribly poor still images, much worse than the Pentax, so I never tried because it seemed pointless.

10

Face and Body Scanning / Re: Minimum number of cameras for human body?

« on: May 08, 2014, 08:41:18 AM »

Are you sure that 80 cameras are really the minimum for my purposes? It seems to me that the War Thunder project has a higher requirement for texture and facial detail ("most visually stunning and realistic characters ever seen in computer generated cinematic" as opposed to "no head or texture necessary") as well as clothing (thematically significant period clothing vs no clothes at all). Because they run a shop specializing in cinematic effects, I would also have thought that they might have higher requirements for hassle-free operation and industrial scale output.

It says on their page that
"Using our 80 x DSLR photogrammetry rig we captured over 20 different high res body and head scans with various poses and expressions."

Is this really the minimum requirement for capturing a pure body form without any need for texture or even the head of the model at all? I always thought that since we as humans have a very good ability to discern subtle facial expressions, capturing faces for cinematic purposes would be among the most demanding uses of photogrammetry, and therefor that type of operation would have significantly higher demands on image quality.

11

Face and Body Scanning / Re: Minimum number of cameras for human body?

« on: May 08, 2014, 03:36:21 AM »

No, of course not  I need to make a scan of a real human, in different poses.

12

Face and Body Scanning / Minimum number of cameras for human body?

« on: May 08, 2014, 01:53:56 AM »

Hi guys!

I want to get a 3D scan the (naked) upper and lower body of a person, for use with clothes tailoring software. I'm a poor student, so I want to build a rig with CHDK compact cameras (or similar).

The model will not require any texture or facial details. That might help make the camera requirements easier. The only thing I'm interested in is getting something like a 1/2"x1/2" mesh with no more than 1/8" error at any point. The person being photographed can wear skin-tight clothes with reference points drawn on them if that helps (or even drawing straight on the body).

I will build a static "cage" rig for the cameras, since that seems to get the best results.

My question: What do you think is the minimum amount of cameras I can get away with? Any tips, or gotchas?