Forum

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - mala

Pages: 1 [2] 3 4 ... 8
16
Face and Body Scanning / Re: Setup for face scan
« on: September 12, 2014, 11:04:12 PM »
Hi wesclei,

I can only give a biased answer to your question regarding triggers..... my signature below "Esper" may explain why ;)

Cheers,
mala

17
Face and Body Scanning / Re: Setup for face scan
« on: September 12, 2014, 12:13:42 AM »
1- t5i/700d is ok but the 100d/SL1 is cheaper
2- kit lens is ok but prime lens is better,rather than the f1.4 most people use the f1.8 50mm this cheaper and very good !
3- the NDC relay controllers are interesting but maybe a bit overkill to trigger cameras as the camera trigger current and voltage is actually very low
4- smart shooter is a good choice , but triggering via USB is not a good idea because it does not trigger all cameras at the same exact time.
5- there is a lot you can do with the standard version of PS, I would say if you are starting out then you do not need the Pro version.

Hope that helps  :)
mala

Ps **Forum mods** It really is time that we had a FAQ section pinned at the top of this forum section to make it much easier for new users ....and the rest of us!

18
Face and Body Scanning / Re: Triggering and Camera Questions
« on: August 28, 2014, 07:43:31 PM »
I'm probably not best placed to answer the question regarding noise in the built models, as I'm mostly focused on hardware nowadays.
But from past experience I would say that to an extent more cameras will help, provided your images have as little noise as possible (low ISO) and a sharp focus through a wide depth of field.

Though even if you do keep image noise to an absolute minimum there will still be some fine noise in the built mesh (from my experience) this appears to be inherent in the agisoft process and there have been in the past various requests for an in application smoothing function.

A lot of people here at the forum are using agisoft to then 3D print models or produce medium resolution assets which may not suffer so much from this fine noise, as I don't know your intended end application for the models I can't say if this will be a problem for you or not.

I think Lee (Infinite) maybe the best person to throw some light on the best way to deal with this fine noise problem really, as he has far more experience with this software and Zbrush when producing very high quality models for various end uses.

mala

19
Face and Body Scanning / Re: Triggering and Camera Questions
« on: August 28, 2014, 01:47:28 PM »
Hi gtarplyer,

I can answer a few questions for you  :)

The Sony cameras are great and very fast, but I would not advise you use them for this application, the problem is Sony's proprietary connectors for triggering and Breeze or Smartshooter currently do not support downloading of images from Sony cameras (Sony are very guarded with all their SDK info that would be required to make this happen)
I would recommend Canon DSLRs for ease of finding trigger cables/adaptors (simple 2.5mm stereo jack) and cheap PSUs...... the best at the moment in terms of cost versus quality is probably the 100D.

Triggering via USB is not a good idea as, yes as you mention it is not possible to trigger all shutters at exactly the same time.

The ShutterCell I can of course give you plenty of info about  ;)
There is a ShutterCell info sheet here: 

http://www.esperdesign.co.uk/assets/manual-_sc.pdf

If you used one of our ShutterCells you would need something to trigger/switch the input, most people use one simple radio remote for this such as the Pocket Wizard, this means you can be anywhere in the room (or in the middle of cameras for a 3D selfie) and trigger all the outputs without getting tangled up with the cable.
You could of course just use a simple cabled remote into the input if desired, but beware any that have half press AF function, as even if you have AF turned off on the cameras(as you should) the signal can disrupt some cameras and lead to unreliable shutter control.

For large camera rigs it would be cheaper to use the ShutterCell rather than one PocketWizard for every camera, plus you don't have to worry about batteries on the PocketWizards.

You will still need Smartshooter(cheaper) or Breeze to download the images to your attached computer unless you don't mind taking memory cards out to copy the images over, though this is time consuming and risks moving your cameras.

Hope that helps,
mala

20
General / Re: Macro Photoscan
« on: July 25, 2014, 07:11:12 PM »
Wow! 

For such a tiny little creature, I'm very impressed with your results.
How many photos did you use ?

Cheers,
mala

21
Hi Eunchi,

We at Esper make an opto isolated cam trigger, see our website for details:

www.esperdesign.co.uk


mala

22
General / 480 cam 4D rig anyone ?
« on: July 22, 2014, 12:08:01 PM »

23
triggering multiple cameras via their USB connections will always create delays, it is an inherent problem with usb.

If you are working with multiple different cameras then I would have thought that you would need to slow all the shutters down to try and compensate for the different "reaction" times... even working with identical DSLR cameras it is very hard to get perfect sync at high shutters speeds due to tiny differences in shutter lag.

If you could get enough constant light on your subject (without blinding them!) then yes removing the flash would maybe work for higher shutter speeds.

Or you need to work out the differences in shutter lag and find a way to compensate for these delays when triggering...

24
Face and Body Scanning / Re: Scanning birds or stuffed animals
« on: June 25, 2014, 04:28:08 PM »
Cool dog scan :)

Regarding polarising filters, I found from experience that it does help somewhat with hair, though i use linear polarisers on both lights and cameras.... so maybe a bit different to what you may be after.

In general I would be tempted to say that most studios would actually try to avoid scanning hair at all for hi res capture(by using a hair net/hat) if the final assest is likely to used in a feature/game where the hair would need to be animated anyway.....and hair system would be used to recreate it.

Things are changing on this front, it looks like there will be some intersting papers regarding hair at Siggraph.

Of course if you are scanning for 3D print or low poly asset then it's a different matter..if hair is tied back or relativly "dense" then polarisng may improve results.... but I would imagine if it's "wispy locks" it won't help as this a different problem.

Cheers,
mala

25
Face and Body Scanning / Re: More megapixels or better optics?
« on: June 25, 2014, 04:15:36 PM »
Personally given the choice listed above I would go for fewer but better (i.e. more Mpix and interchangable lenses) DSLRs.

Way back when I first got Photoscan I had just one Canon 450D.... this alone  was easily adequate to complete face scans, provided the person was still as possible and there was adequate lighting.
I then bought more 450Ds on Ebay (pretty cheap) and made a rig of 3 cams, to this I added at a later date more 450Ds..unitl I ended up with 8 x 450D... The results were fine at the time.
I eventually sold all these cameras and the 50mm prime lenses I had bought, back on Ebay...... the thing to remember is that Canon DSLRs in general hold their value pretty well provided they are taken care of,as do the lenses.
At some point you are bound to want to upgrade your cameras for more Mpix, faster shutters,etc...so it is
worth having something that has a resale value.....

Cheers,
mala

26
Face and Body Scanning / Re: Mounting cameras to light stands
« on: May 11, 2014, 05:34:54 PM »

27
Face and Body Scanning / Re: LED arrays
« on: May 08, 2014, 06:49:24 PM »
ok lets do some maths :)

320*700=224000   8) correct but we have filters in front of LEDs that ONLY transmit 40% of light,

40% of 224000 = 89600  ;) then sometimes we have some more of the same filter in front of cameras that again only transmit 40% of light.

40% of 89600 =35840  ??? where did all the light go !

These LEDs are not just in front of the subject, they are all around the subject.....

No we are not using "continous light" as such... that suggest you turn the LEDs on,walk away and just leave them on... that is not what we are doing...we can have the LEDs on full at 100% for very long periods of time and WITH the filters in place its is not too uncomfortable, but without the filters it would not be pleasant...fortunately as mentioned before all LEDs are dimmable.

Cheers,
mala

28
Face and Body Scanning / Re: LED arrays
« on: May 08, 2014, 06:01:51 PM »
Hi there,

My LEDs are not being "powered up" at 0.5ms... what I said was the exposure time of the camera was 0.5ms.

My setup is rather more complex than just a PSU.

The LEDs each have their own driver, the LEDs are mounted in pairs on a custom heatsink, to which is also mounted a custom PCB which contains the two drivers and micro for control, with data and power connections.
Each LED requires approx 18Volt DC, this is supplied by a distro system (yet another custom PCB)
The DC power distro system is ultimately fed by 12 x 24VDC 13A power supplies in a rack system.

My LEDs are all individually controllable at very high speeds with either 8 or 16 bit dimming.

I'm sorry but that is as much detail as I can give at the moment.
Suffice to say this is not a quick and easy solution to make.

Cheers,
mala

29
Face and Body Scanning / Re: LED arrays
« on: May 02, 2014, 07:22:25 PM »
I don't think you will find any high output high CRI LED strips for a low price i'm afraid.... these things are made as cheap decoration light and you may have problems trying to turn them on/off at the speeds you talk about.

If you were to use the orginal Cree COB LED you mention...  again controlling these at high speeds may in fact be quite expensive given the voltages required.

Personally I don't really understand what you are doing with the "moving arm design".... it does look cool but I think you will end up spending more money in the longterm trying to compensate for the movement of the cameras and additional light needed to shoot at the high speeds.... when you could just buy more cameras and have a fixed rig.

One interesting and cheap LED light source are LED panel lights like this kind of thing
http://www.ledhut.co.uk/45-watt-high-powered-panel-light-1800-lumens-600-x-600mm.html
they come in various sizes are bright and produce a very diffuse light..... but even the small 300x300mm ones will be too big to put on your rig of course.

mala

30
Face and Body Scanning / Re: LED arrays
« on: April 30, 2014, 11:48:58 PM »
Hi there,

I'm not sure how much I can help here...
I will agree that in order to compete with a standard flash unit (but it is notoriously difficult to actually get an accurate lumen reading for flashes due to their speed) that you would require COB LED.
In my experience it is not difficult to PWM or current dim a COB array but special attention has to be paid to how the individual diodes in the array are wired, often they can be more than one parallel string of series diodes.
Therefore there will be a minimum current usable across the array that may not be exactly logical ..
In terms of CRI, if you buy quality LEDs and choose something in the region of 5000-5600k I don't think you will have a problem.
Nearly all ( maybe 95%) of high CRI LEDs are so called "warm white" 3000-3700K  these are so numerous because they are used as a replacement for filament/tungsten lights....these actually cause more problems for accurate texture colours in photographs of skin than using lights of a higher colour temp.
Xenon flash by the way IS a much higher color temp ..... Basically use 5000-5600k or maybe even high as D65.

I do think that if you actually manage to get the lumen output you talk of,which is very rare to get stated output ....then this will be way too bright for your subject even at the very short times you talk of.
For example I have recently done a test shoot with 320 LEDs around a subject,each Led is 700 lumen, we use polariser film on lights (transmission 40%)
Our cameras have another polariser film(transmission 40%) camera exposure time is 0.5ms.
The resulting images are sufficiently lit.
Cheers,
Mala

Pages: 1 [2] 3 4 ... 8