What cameras/lenses are preferable for photoscan?

[andy_s]

I'll leave SDM and additional hardware for the future, I think i'll go the usbremote way for the moment and if things don't go as expected I'll have to call the SDM chivalry. Thx for your help!

Hi ikercito - the RC receiver / proSDM solution is [probably] only useful if a totally wireless triggering / tethering solution becomes possible / is required. Even then, I don't think the 'synch' would be as good as using any better than a simple 'button switch', as Chad first described here http://www.agisoft.ru/forum/index.php?topic=1378.msg7164#msg7164.

The caveat is -

It was then 'EMULAT3D' who suggested switching via the powered hub here http://www.agisoft.ru/forum/index.php?topic=1378.msg7179#msg7179- however, i'm not sure if the added circuitry within the powered hub [above that of the simple 'button switch'] results in voltage decay timing variances between each hub outlet.

There is also this to consider [for both hub / simple 'button switch' solution] http://chdk.setepontos.com/index.php?topic=8769.msg105454#msg105454:

"5/ However you have to be aware of a another potential problem, that in a "Standard" Sync USB cable there is no "Discharge" path, except for the camera's internal non linear circuits. This has been a subject in several previous posts and dosn't appear to be a problem with twined cameras but could be major problem with your rig that has a combination of long USB cables and 50 cameras."

Anyway, I hope the hub solution results in adequate results for you - it definitely has the benefit(s):

• simplicity
• allowing image transfer [non-trivial, admittedly] as described by EMULAT3D [link as above]..."Then to pull the images off (still a pain and not ideal) we would just disable remote trigger on the cameras, then connect the hub to the PC to retrieve images (via Windows Picture Import). This is nice because you can then tag the images to a specific camera number."

After the actions at point 2 above the camera is back in a state that you could 'program' image transfer by client chdkptp lua script - but, initially, learning this will be time consuming [for me also] and not particularly productive - unless you get round to implementation of the hack I described at reply #20 in this thread.

What camera model are you using ? [hope i'm not asking for info already posted  ]

[ikercito]

Wow andy_s... you're such a source of information! Thanks a lot for all the time you're taking. As you said, right now the best and easiest way to go is the usbremote and usb hub method. I'm not that concerned about exactly precise syncing, I'm not planning to do action scans so a little delay in sync should not be too bad.

I've done tests with only one camera (Nikon D700, keeping my subject still and shooting around it), and the results have been really impresive. A little noise in some areas, and probably not the best definition around the eyes area. There's room for improvement so I'm going to try to rig an Ixus 80 borrowed from a friend (never been a canon guy, have a big bunch of different nikons, sony and panasonic though...), with four Ixus 105 and a S95 that are coming next week. I have big hopes in the results when i rig them up and shoot synced.

Another concern is that I'm not sure if any of these cameras allow aperture control (do they have a real diaphragm?!?) to maximize sharpness all around the subject. Manual settings on CHDK are quite a PITA to set up manually, but I guess I'll manage to get them done.

I haven't had much luck with ptpcamgui, as it couldn't see the camera connected... Thought it might be useful to go that way, but i'm about to ditch it since I believe it's going to be even worse with 6 cameras. The usb hub method sounds more reasonable and reliable. The next step will be retrieving the pictures "auto-magically" direct to the computer... I'll keep you informed about my progress. I think that's going to be a hard trick to pull, so I'd better build some patience in case I have to revert to the traditional card reader method.

Thanks once again for your help.

[andy_s]

... you're such a source of information!

I'm not so sure, just trying to help. Please also treat any thing I say with healthy skepticism [none of it is based in practice].

Surely many things count - including MPix. Those A3300's that Chad uses are 16Mpix.

E.g, this from 'Infinite' [Lee] for DSLR's http://www.agisoft.ru/forum/index.php?topic=942.msg4645#msg4645

"...anything below 18MP really isn't great. You get OK results with 12MP but it's not ideal."

Re aperture, this from chdk guru 'reyalp' [in answer to, yet another, newbie query by me] http://chdk.setepontos.com/index.php?topic=8769.msg106057#msg106057

"Some have adjustable aperture, some don't. Most of the ixus and recent A series do not."

I'm currently 'battling' through this topic from the German CHDK site - chrome tries well at the translation but it misses some stuff. More generally, the thread does show that chdk multi-cam implementations are far from straightforward http://forum.chdk-treff.de/viewtopic.php?f=20&t=2037   

Finally,

Some further excellent advice on that aforementioned post from Lee:

"...The key is sharp, focused, contrasted images. As much detail as possible, for good reconstruction.

Ideally you want access to USB, trigger and continuous power for your devices. Once they are running it's best not to have to physically touch them again, until you shut down. This way you can re-use camera alignments (very effective)."

I remember looking at 'dummy' batteries for some Canon P&S that don't have external power available - but can't find the link [just one more important point to consider]

Looking forward to more of your progress 

PS: I haven't read [much] about ptpcamgui and don't plan to.

[ikercito]

Well... Lee is the absolute master in this area, his tips are always words of wisdom. But I guess i can manage with a little less quality. His work is impressive, and his hardware too! Maybe sometime in the future i can get close to that, but as of today I'll do my best with the material I can afford. I'm really hopeful the results will be reasonably good, but we'll have to see how everything goes when i get the new material.

Aperture is going to be a tough one to beat, I hope i can force the cameras to get some deep DOF somehow... I'll pump everything with as much light as i can, and should build some kind of DIY dummy batteries for the cams. There are so many things to consider...! I'll keep you informed.

[andy_s]

Well... Lee is the absolute master in this area, his tips are always words of wisdom.

Not necessarily http://www.agisoft.ru/forum/index.php?topic=1411.msg7106#msg7106 - but I see you posted there already 

Enjoy the rest of the weekend,

Andy.

[ikercito]

True....!!!

[chadfx]

Ikercito: I'm glad to hear you're getting a chance to start your experiments! As you suspected, I think a lot of the simpler Canons do NOT have an actual aperture control. They use an ND filter (which you can control with CHDK) to help control exposure. That being said, even with my cameras shooting at f2.8, I am still getting enough DOF with a subject about 0.5-1m away...it's that small sensor and somewhat wide focal length that makes this generally possible. If you are closer to your subject and it has a certain amount of depth, then you might start to run into issues.

I also did not find the manual controls inside CHDK to be very fun to use. I was hoping to use them for focus bracketing, but I wasn't able to get satisfactory results (& ran out of patience). Some of those controls (like aperture mentioned above) might be more controllable/reliable on the more capable cameras like the G series.

Also, you might get slightly more mixed results from using the various flavors of cameras for your testing, but generally you'll probably get a decent idea of if it will work for you.

for you & Andy:

For rigging up a permanent power supply to the cameras. There are cheap-ish 3rd party solutions:

http://www.ebay.com/itm/HQRP-AC-Power-Adapter-DC-Coupler-fits-Canon-ACK-DC30-NB-5L-/390502463354?pt=Camera_Cables_Cords&hash=item5aebc2b77a

and it's possible to build your own if you're feeling handy with some tools:

http://techwatch.keeward.com/geeks-and-nerds/make-your-own-ack-dc30-adapter-kit-for-canon-camera-with-a-nb-5l-battery/

You can get some pretty cheap 3rd party batteries on eBay and simply ditch the battery guts on the inside (well, you'd probably recycle/dispose of them properly of course. =)

[andy_s]

Hi Chad - thanks for the battery link...

Edit: this also for remote camera turn on/off http://chdk.setepontos.com/index.php?topic=9271.msg98552#msg98552

"You solder two wires to the power switch or view pictures button and attach them to the relay.
Once this is done you can flick the relay on and off to replicate pressing the button."

In more detail ['Camera 2' description]:

http://www.antthomas.co.uk/webcam/guide.php

[ikercito]

Thanks a lot Chad, that is very handy. Not sure if I'll go the DIY route or not, but I guess a proper power supply will be very necessary.

Regarding DOF and focus... I will only be able to judge once i get the cameras in. Let's hope things turn out right. It's a pity that cameras like my trusty panasonic LX5 can't be synced together. It's small, has a nice sensor and plenty of controls to play with... Unfortunatey, there's no way to shoot it remotely.

As you said, CHDK is totally unreliable in order to set things manually... Menus, menus, and more menus... Absolutely nerve wracking! Let's build up some patience... And regarding the mixed camera flavours, right now is the only thing I can afford so wish me luck!

Thanks guys for your help.

[chadfx]

Ikercito, you might want to consider one of Canon's S-series cameras (S100, S110, S120). The refurbished versions of the 100 & 110 are around $200-250 (US) and they have a sensor size and image quality similar to the LX5 (not to mention smaller/lighter bodies).

http://www.dpreview.com/reviews/canons100

Not as cheap as the A series point and shoots, but comparable to the LX5 for sure.

[ikercito]

Thx Chad. Already checked those, i really like the S100 i borrowed from a friend. Unfortunately... that's too expensive for the moment.

BTW, is there any list at CHDK (or elsewhere) where i can find which cameras have a real aperture, and not just a ND filter? I remember seeing something similar at chdk some time ago, but can't find it now.

[chadfx]

I don't know of a specific list anywhere, but that certainly would be nice to discover.

[ikercito]

Found something... I'm not sure if the diaphragm column refers specifically to having a real aperture... But i guess it's a start

http://chdk.wikia.com/wiki/CameraFeatureTable

[chadfx]

Nice find, that sure looks like it, based on which cameras have a diaphragm and which don't.

You've probably seen this page, it describes the ND filter functionality on the cameras and related to the diaphragm issue:
http://chdk.wikia.com/wiki/ND_Filter

[hengefjes]

Did anyone try the Olympus Zuiko Digital 7-14mm F4.0 ED fourthirds lens with Photoscan? That "field of view" seems perfect for my line of work. I'm documenting ship interiors/exteriors, and planning to get a Olympus OM-D E-M5 and this lens (if it isn't to wide-angled for Photoscan, that is). If I understand it correctly, these fourthirds-lenses have a built in lens profile that corrects chromatic abberation and other flaws before its saved as RAW in the camera.

hengefjes: Sounds like a good setup. Altough.. I've never done room scanning. I suppose the workflow should be different to mine, so i can't help you much. By the way, the lenses have their profile on the camera, not on the lens (am i worng?), and most of the times it's applied to correct the JPG output only... just playing by ear here.

Thanks for the reply, Ikercito. I seems like you are right. The parameters for lens correction is saved with the RAW file so that software like Lightroom will know what to do. I'm still curious about the lens I mentioned. Should I worry about it being too wide?

Added: The crop factor is 2, so this should be equivalent to 14-28mm fullframe.