Agisoft Metashape

Agisoft Metashape => Face and Body Scanning => Topic started by: ttoke on July 24, 2014, 09:04:35 AM

Title: Building a 39 camera full body rig
Post by: ttoke on July 24, 2014, 09:04:35 AM
Hello guys,

We are currently building a 39 camera full body scanner. Setup:
15x  Canon 1100D + random 18-55 lens
24x Canon 1200D + random 18-55 lens
8x 110W softbox lightning
39x triggers (connected)

The cameras are on 10 different stands, 2 of them (front and back) are holding five, most of them four and three are holding only 3. The distance between cameras is 1m. 

We are having difficulties in getting a good scan. The program usually tries to make a model of walls, floor etc. When it does a model of a person, it is usually only half of the body or two separate halfs. We had pretty good scans in the beginning when we had only 24 cameras (of half of the person), but after buying more cameras and lightning, we haven't got any satisfying results.

Some questions:
1) Is there a "perfect" focal lenght? Should we take pictures as big as possible or rather zoom the cameras in and try to make 3 pictures (every angle) of different parts + one big "general" picture?
2) Can the light be in different colour? Should we close the window, shut down the room lightning etc? (room lightning is kind of yellow, softboxes are white).
3) Should we keep the cameras seperated evenly or rather create "clusters" of them?

Any tips are welcome, thanks!
Title: Re: Building a 39 camera full body rig
Post by: ruffy on July 24, 2014, 12:42:46 PM
Most people are pretty secretive of their I.P.
You may not find much help here.
Like you, I am having to experiment.
This is going we'll, but takes time.
I think I am close to great results in a few days time.
I have 60 old cameras.
If it works then I will invest in 80 new ones.
Good Luck:)
Ruffy
Title: Re: Building a 39 camera full body rig
Post by: James on July 24, 2014, 01:49:08 PM
My area is architectural and structural so don't mind sharing some IP :)

With cylindrical concrete columns I found 10 cameras in a ring around the cylinder to be the absolute minimum to get it all to link together, and found 16 to be the practical minimum most of the time.

Humans being a funny shape probably require a few more setups.

You could try more stands with fewer cameras per stand, maybe 3 per stand on 13 stands, to see if it helps you register all the way around, then add more cameras when you can afford to in the areas you need more detail.

Another idea could be to use the 10 stands you have with 3 or 4 cameras each, and slant your stands at an angle so you effectively have 39 cameras evenly distributed all the way round horizontally, albeit at different heights vertically.

You can try moving the cameras further from the subject, up to a point, to increase their view around the subject and therefore increase overlap.

I have had success with focal lengths all the way from 10mm to 55mm on my crop sensor cameras, albeit only ever static objects with a single camera. I would say if you are struggling then go wider to increase overlap, but not to the point where your subject is no longer filling the frame, then zoom in until it stops working.

Back when Infinite started posting on this forum I saw he was getting results with 40 cameras, so it can be done (http://www.agisoft.ru/forum/index.php?topic=385.msg1604#msg1604 (http://www.agisoft.ru/forum/index.php?topic=385.msg1604#msg1604)) but like ruffy says you have to experiment and it doesnt come for free!
Title: Re: Building a 39 camera full body rig
Post by: CreativeCharacter on July 25, 2014, 04:45:33 AM
I don't think you can look at this site and say people are secretive about their "I.P."s. there is a wealth of information on every possible topic if you hunt around a bit.
Title: Re: Building a 39 camera full body rig
Post by: ttoke on July 25, 2014, 08:41:22 AM
Thanks guys! I'll keep You updated!
Title: Re: Building a 39 camera full body rig
Post by: Wishgranter on July 25, 2014, 01:40:53 PM
Hi ttoke.
Good that you want go for FBody scannign but still im highly recomend to ask Lee for consultancy. He knw a lof of things from real use  with all the "secret" stuff. and in   end, you can save 1.000 of EUR when  go afther his  recommendation + you are sooner market ready....
Title: Re: Building a 39 camera full body rig
Post by: ruffy on July 27, 2014, 10:51:30 AM
Happy to admit that I may be wrong with people being protective:)
How should I contact Lee for consultancy?
Title: Re: Building a 39 camera full body rig
Post by: meshmixup on July 27, 2014, 03:37:28 PM
Happy to admit that I may be wrong with people being protective:)
How should I contact Lee for consultancy?

Yes, I want to know too. :)
Title: Re: Building a 39 camera full body rig
Post by: meshmixup on July 27, 2014, 03:42:37 PM
3 cam per column in portrait mode 35mm and total 12 column can make reasonable results for stand still pose. 3 extra can put at higher position for head close up
Title: Re: Building a 39 camera full body rig
Post by: ttoke on August 08, 2014, 05:53:46 PM
Thanks! We got some decent results already, a little bit tweaking and it should be OK for us at the moment.
Title: Re: Building a 39 camera full body rig
Post by: ttoke on August 13, 2014, 08:44:43 AM
Ok, the results weren't good enough. We bought 10 more cameras.

Is there a "perfect" distance from cameras to the centre of the scanner? At the moment I think it's about 1.5-2m but I think we should make it smaller..?
Title: Re: Building a 39 camera full body rig
Post by: meshmixup on August 13, 2014, 10:26:48 AM
Considering different model poses and DOF, 2.5m radius is more flexible ;D
Title: Re: Building a 39 camera full body rig
Post by: ttoke on August 14, 2014, 09:14:53 AM
Considering different model poses and DOF, 2.5m radius is more flexible ;D
Thanks!

Should we use same focal lengths on all the cameras? Right now it's a mess - every camera has its own focal length. We use Canon 1200D/1100D "stock" lenses.
Title: Re: Building a 39 camera full body rig
Post by: meshmixup on August 14, 2014, 11:58:27 AM
I do not have any issue on using different focal length in one shot, PS will do all magics  ;D

Agisoft has the following recommendations on lens settings
Lens:
Fixed lens are preferred. If zoom lens are used – focal length should be set either on
maximal or minimal value, if this condition is not provided each zoom-lens camera should
be calibrated separately;
Try to use minimal possible camera/lens models and different focal length
Title: Re: Building a 39 camera full body rig
Post by: ttoke on August 14, 2014, 12:07:51 PM
I do not have any issue on using different focal length in one shot, PS will do all magics  ;D

Agisoft has the following recommendations on lens settings
Lens:
Fixed lens are preferred. If zoom lens are used – focal length should be set either on
maximal or minimal value, if this condition is not provided each zoom-lens camera should
be calibrated separately;
Try to use minimal possible camera/lens models and different focal length


Thank You for the help! :)
Title: Re: Building a 39 camera full body rig
Post by: Lambo on August 15, 2014, 12:02:56 AM
Yes I am also using all different focal lengths in 60 cameras and I still get pretty nice results. I know it could be better but it seems Photoscan does a great job compensating there.
I work on an oval shape area that is around 2.4 m by 3m that's why I need all kinds of focal lengths.
I use F11 that seems to be the best in my case but that varies depending on many variables like for example the amount of light and you seem to have more light than me. I only have 3 flashes.
Leo
Title: Re: Building a 39 camera full body rig
Post by: ttoke on August 15, 2014, 10:11:06 AM
Sounds good! Actually we bought even more lightning - now we have 10 softboxes with 120w continuous lightning. If we were smarter before, would've used flashes, too. :)

One more question:
Do You guys mask all the pictures manually or does automatic masking work well for you? We have tried automatic masking, but we haven't got any decent results yet. It seems that there is a small movement between two pictures (with an object and without), probably caused by 4 DSLR cameras taking a picture together on a cheap lightning stand.. Also, auto focus is also a problem (the cameras focus on the background on the "empty" picture).

Is it possible to get decent results without masking? We have no luck so far.. usually PS mixes up the back and the front end of an object and creates a very "interesting" object..

Thanks for everyone participating in this thread, you are being very helpful!
Title: Re: Building a 39 camera full body rig
Post by: meshmixup on August 15, 2014, 10:31:23 AM
Hi there,

My cameras are not mounted on permanent structure so they can have some displacement after few photo session. One of the solution is to take a set of background photos after/before every capture session. Try to link up the stand can also help to stable your camera. :)

If you have a lot of objects in the background, I am afraid you have to mask it out. I am using white background so I can get photo aligned with /without masking usually. But if someone is wearing white shirt, my nightmare comes.  Lambo knows it ;D
Title: Re: Building a 39 camera full body rig
Post by: ttoke on August 15, 2014, 10:54:17 AM
Haha, I imagine.

As we are planning to scan brides with white dresses, white background is probably not best for us. What about green? :)
Title: Re: Building a 39 camera full body rig
Post by: meshmixup on August 15, 2014, 12:15:25 PM
I did not try different background colors, but I think it will do and you may need to tune up the lighting
Title: Re: Building a 39 camera full body rig
Post by: Digitage on August 15, 2014, 08:23:08 PM

1) Is there a "perfect" focal lenght? Should we take pictures as big as possible or rather zoom the cameras in and try to make 3 pictures (every angle) of different parts + one big "general" picture?


Regarding focal lenght, from my experience there is a balance to find. Basically, when you zoom in a lot, you get more useful data from your model in the picture frame, but you also weaken the robustness of the camera positionning in the first step of your photoscan process, and if your model is not standing in the middle of your rig and your zoom level is important, you risk shooting halfway out...
Title: Re: Building a 39 camera full body rig
Post by: Lambo on August 15, 2014, 09:56:20 PM
Yes, I know about white dresses! It becomes a nightmare as meshmixup says :) But if the white dress has lots of material texture like stitching or small holes, etc. it helps a lot.
I dont think I would recommend green background since any color close to the subjects bleeds out and the dresses will come out with a slight green tint unless you have the background pretty far from them.
At least that is my experience, I don't know if anyone is using a colored background successfully?
I would guess a possibility is to have a mid grey background?
Also very important, try to go away from auto focus. It is not as important in a constant light situation as yours compared to the flashes but still you can get a few cameras that didn't focus correctly on each session and you will loose important info for the PS process.
You should get someone with nice easy to focus clothes (jeans for example) in the center of the shooting  and manually (or automatically) focus all the cameras. When you are sure all of them are well focused (you should zoom in at least 200% to verify) then you turn them to manual focus and leave them that way.
The masking can be tuned per chunk or per photo if you want. Just use the tolerance slider on the import masks window before applying the mask and test a few different settings until you get the best possible one. After that you might have to do some manual tweaks on each photo anyway.
Leo
Title: Re: Building a 39 camera full body rig
Post by: ttoke on August 18, 2014, 02:25:55 PM
Thank you very much! We will try different solutions and let you know.  ;)
Title: Re: Building a 39 camera full body rig
Post by: barkerjs on September 04, 2014, 05:39:15 PM
I'm curious as to what cameras people use for these set ups.  Anyone willing to share their experiences?
Title: Re: Building a 39 camera full body rig
Post by: meshmixup on September 05, 2014, 05:36:59 AM
Hi, I am using a mix of canon DSLR, 550d, 100d. You may find others are using D3200, 5D markIII or even  raspberry pi. :)
Title: Re: Building a 39 camera full body rig
Post by: Lambo on September 05, 2014, 08:29:44 AM
I am using all Nikon D5100's.
Title: Re: Building a 39 camera full body rig
Post by: ttoke on September 05, 2014, 12:33:37 PM
We are finally getting decent and continuous results with our 49 camera rig. :)

The problem is USB - we constantly get about 45-47 pictures of 49, some of them get lost on the way to the computer. We use both USB 2.0 and 3.0 hubs, but bigger distances (3m) are covered with USB 3.0.
Barkerjs - we use Canon 1200D and 1100D.
Title: Re: Building a 39 camera full body rig
Post by: barkerjs on September 05, 2014, 06:18:41 PM
That's a lot of money for cameras!  I wonder what kind of results you would get from an array of $50-$100 point and shoot cameras?  I saw the Pi array with those cameras, and that quality seems like it's okay for 3d printing at least.
Title: Re: Building a 39 camera full body rig
Post by: Lambo on September 05, 2014, 11:02:51 PM
If all you are going to do is miniature 3D replicas (no more than 6 inches height) then you can get away with the smaller resolution and quality cameras.
If you are going to do bigger bodies (8 inches or more) or head scans, or some game assets for example, then I dont think those cameras will cut it.
Leo
Title: Re: Building a 39 camera full body rig
Post by: barkerjs on September 08, 2014, 12:18:36 AM
Interesting.  If I'm doing a full body scan, I'm willing to bet that it's still better than using a Sense scanner or Kinect.  I'm not creating any game assets, just models to display online and to 3d print in color.  But I'm intrigued by the idea, and if the cheap cameras do well, I might be able to step up to nicer DSLR cameras in the future.
Title: Re: Building a 39 camera full body rig
Post by: ttoke on September 08, 2014, 08:47:16 AM
Good luck. The results will be horrible, but keep us updated.
Title: Re: Building a 39 camera full body rig
Post by: MetaUser555 on September 18, 2014, 04:39:54 PM
Is it possible to get decent results without masking? We have no luck so far.. usually PS mixes up the back and the front end of an object and creates a very "interesting" object..

[/quote]

The best results are masking 100% of the time, you won't get any color bleed when you come to create your texture. If you use photoshop to mask, you should be able to to do each image manually in about 30secs using good techniques for a simple head [if this works practically for the volume of photos you're going to take obv :) ]. Auto masking using a background is ok but not great: think of the magic wand in photoshop the results are about the same. If you have a different colored background it improves things but then you'll get that color reflected into your subject which you may not want. Hope this helps.