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Messages - tommyboy

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Thanks Magnus, Lambo, ruffy. I love these forums!

Since we are usually capturing people being still, do you think the faster strobe is necessary? At one point a 3DMD representative told me that the threshold for perceptible human movement is 4ms (1/250), even when the subject is trying to be still.  Without being able to measure our current strobes (and no published specs, they are cheap), it's hard to know if we'll get a difference from an expensive upgrade like this.  Hopefully the local shop will let us demo/rent first...really great to know though, thanks again.

We have our cameras going at 1/160th, and we still see motion blur on jumping subjects. We had also previously done the technique suggested by Lambo, and got the same result.  Best fix so far has been to watch the subject while they jump, and fire the cameras at the peak of their jump, which minimizes motion blur to where you can get a good solve from the pictures.

Face and Body Scanning / Re: About ultra high dense could generation
« on: October 01, 2014, 09:43:07 AM »
There is no easy answer for this. It is unfortunately hard to advise what are "good" values on the forums, as it's based largely on personal needs, preferences, and judgement. I thought our initial results were pretty good, and there was no point to ultra high.  Now that we've improved our technique I know better. :)

Key to this is having good diffuse lighting, and sharp enough images that the processing will benefit from the full resolution of your images, as opposed to the 1/2 resolution that it uses for high.  To get this you need good focusing and/or prime lenses. Sharp sharp sharp.

Face and Body Scanning / Re: Head scans in the Los Angeles area?
« on: May 09, 2014, 09:21:16 AM »
Thanks for the suggestions thus far. We are aware of ICT and Giant, but we are specifically looking for a high end photogrammetry set up for its ability to capture a facial expression instantly. While Gentle Giant and ICT are both very reputable vendors, their acquisition times would be too slow for our needs.
ICT's setup is photogrammetry-based, they wrote all their own software for it. You may be confusing their reflectance field capturing, which does require holding still for awhile, with a purely geometric scan, which is instantaneous. Others who have worked with them more recently said that they do indeed do scanning of full FACS poses.

+1 to Lambo.  Many people, myself included, are getting good body scans including the head, using 50-60 cameras.  You could probably get by with less if you have a clever way to turn a rough body scan into a collision volume, which it sounds like is what you need.

Face and Body Scanning / Re: sync 550d and USB connection problem
« on: May 08, 2014, 03:20:46 AM »
Canons in particular have a high level of variability in shutter lag, so even firing on the second curtain, you are probably going to get some black frames. It is definitely important to prefocus cameras before firing as this greatly reduces the variability in shutter lag, but it still happens. Most reliable is to introduce the delay as suggested, for which the formula is:

1) Set shutter speed to be somewhat long (1/10 generally as mentioned by many)
2) Introduce a delay for the strobe firing that is 1/2 of the shutter speed, for best chance of all shutters being open when the strobes fire.

This is the approach that I have used to great success, you can get the shutter speed lower still even, but why bother when this works 100%.

In our case we use a PocketWizard Plus X (cheapst model) to transmit the signal, and MultiMax to receive the signal and introduce the 1/20 second delay before passing the signal on to the strobe. I believe a Camera Axe will allow you to do the same thing for cheaper, but requires a bit more work to set up.

Face and Body Scanning / Re: Floor for body scanning area...
« on: May 08, 2014, 02:30:55 AM »
Not sure where you are geographically, but if you are near a Home Depot then rejoice. We have jiggered up many solutions from there, in the case of flooring we got something called Boise Cascade Standard Carb P2.  It is a thin yet rigid particle board, in sheets of about 3ft x 6ft.  It is coated on one side with a relatively tough white finish, slightly glossy, which is good for bouncing light, as well as being easy to clean, hard to get dirty.  It has worked out great, we got a half dozen sheets and tape them with white tape at the seams.

Face and Body Scanning / Re: Head scans in the Los Angeles area?
« on: May 08, 2014, 02:12:04 AM »
Gentle Giant are located in LA and have been in the business just about forever.  There are others with differing levels of ability, Googling can find them pretty easily.  What is your planned use for these models?  Would help to know to make suggestions.

+1 to this request, from a very interested Pro customer! Thank you!


1) the edge of the mask is often too generous in letting in the background, which lets through the white background; this is particularly problematic when creating textures for hair and areas where 'webbing' is likely (fingers, armpit, crotch)

It doesn't really matter how accurate the masks are in this regard as Photoscan still doesn't take into account masks during hole fill stage. Webbing will always occur until hole fill is taking masking into account. I believe this is a complex problem to solve.

It's just as fast to do your editing after dense point cloud reconstruction. Edit / delete the points directly in 3D, then build the mesh. Photoscan will still web but it will produce better results and will be faster than manually editing each mask image by hand.
Interesting point, thanks Lee!  It does indeed seem difficult to gauge how much time it is worth spending on masks, versus simply cleaning the model later.  When I clean the masks I certainly get a reduction in the amount/size of holes, and hole-filling by PS.  When you edit the point cloud directly for the same effect, you are effectively creating holes that will need to be filled.

So that's an important question, what are people's opinions: is the time spent tweaking PS's default masks better spent cleaning the model?

In either case, I'm mainly hoping there's a way to improve automated mask generation to the point that the answer to the above is definitely "clean the model".

Face and Body Scanning / Improved masking options for human scanning
« on: April 03, 2014, 08:29:34 PM »
Hi all.  We've been using PhotoScan's built-in tool to get masks from background images (i.e. a second set of clean plate/empty background images taken right after the subject is photographed).  It does quite a good job, but seems to have the following issues:

1) the edge of the mask is often too generous in letting in the background, which lets through the white background; this is particularly problematic when creating textures for hair and areas where 'webbing' is likely (fingers, armpit, crotch)
2) it often ends up masking out dark portions of the subject if they are in the same spot as a camera lens in the background image
3) due to diffuse reflection of the subject on our white floor, the contact point of their feet with often includes a significant portion of the floor around their feet

So far we have been manually cleaning up these problem features using the PhotoScan tools, which ends up taking a good 60-90 seconds per photograph on average.  Obviously I'd like to take this number down to zero, so have been looking at alternative methods for background subtraction, which I could then feed into PhotoScan.  This project looked like a good option, but ended up having its own problems, and being rather slow:

Is anyone else using external programs for mask generation?  I should know the answer to this but for some reason it is eluding me...


General / Re: Benchmarking a GPUs
« on: March 27, 2014, 10:08:12 PM »
By the way,  Did anyone try  Two SSD  with Raid O settings on this kinda powerful system?
Did you notice any significant performance ?
I have tried SSD vs spinning platter drive, where the performance difference should be much more noticeable, and didn't see any real difference.  I think if you have enough RAM, the only time it's really hitting disk is when loading the photos, and odds are they will be cached by the OS into RAM already, regardless of drive.

General / Re: Benchmarking a GPUs
« on: March 18, 2014, 03:00:32 AM »
Core i7-4930K (12 HT cores), 64GB RAM, dual R9 280X

We got the best GPU performance when limiting to 8 CPU cores as suggested by PS, making the 7970 about 8% faster.  Interestingly, the best overall time was achieved by setting to 10 CPU cores:

8 Cores
Device 1 performance: 160.09 million samples/sec (CPU)
Device 2 performance: 693.38 million samples/sec (Tahiti)
Device 3 performance: 696.031 million samples/sec (Tahiti)
Finished processing in 192.699 sec

9 Cores
Device 1 performance: 161.812 million samples/sec (CPU)
Device 2 performance: 660.052 million samples/sec (Tahiti)
Device 3 performance: 645.288 million samples/sec (Tahiti)
Finished processing in 176.007 sec

10 Cores
Device 1 performance: 162.184 million samples/sec (CPU)
Device 2 performance: 644.929 million samples/sec (Tahiti)
Device 3 performance: 648.454 million samples/sec (Tahiti)
Finished processing in 169.472 sec

Wishgranter, have you been updating your spreadsheet?  Would you be interested in publishing your spreadsheet so far as a shared Google Doc?

Face and Body Scanning / Re: Calibrating Lenses for scan perfection
« on: March 07, 2014, 08:53:56 PM »
I mentioned this a few years back. It would be a good feature to have for sure but I think difficult to implement, perhaps ask in the feature section of the forum? I will +1 it :)
This seems to be possible by hacking Ground Control, have you tried this?  It looks like one could hand-code a CSV file with camera positions from a cameras.xml export.  Or if you add a few coded targets and distance measurements into a calibration scan (and ideally included some coded targets in their regular scan), one could load marker/camera positions from the calibration solve, then "optimize alignment" to solve them exactly.  I'm going to try this, can you see anything obviously wrong with this approach?

General / Re: New GPU to improve speed or useless
« on: March 05, 2014, 07:58:02 PM »

This thread is worth checking out, there is much talk as far as running multiple PS instances to increase CPU core utilization.  I haven't done a lot of careful testing in that regard, or on enabling/disabling hyperthreading, but it did give me the idea to run multiple PS instances for making better use of the two GPUs.  I will work on getting more hard data to support this approach, since my test data so far has just been for one PS instance, but I assure you setting two instances going over the weekend got me many more ultra high dense cloud solves than I got normally..

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