Messages

16

General / pair preselection

« on: November 13, 2013, 08:10:42 PM »

about alignning images
with <120 images, will enabling image preselection (generic) increase or decrease processing time?

secondly, will it make any quality difference to enable or disable it?

thanks

17

Face and Body Scanning / Smooth skin issues and results

« on: November 09, 2013, 08:08:42 PM »

Hi,

see anyone have some insights or similar experience:

i have been scanning a couple of friends' face as test, using my 12 canon rig with a fixed setup of a few 600W flash and f11, iso100. 1/125sec shutter, with cross-polarization setup.

after a few test, im quite convinced that people with smoother skin to less smooth skin/larger pores results in HUGE quality differences:
(not any racial discussion, purely experimental findings) my samples includes Caucasian and Chinese men and girls(without make-up), each group of above contains 2-3 person as samples.
results shows quite clearly that Caucasian men group always produces the highest quality even if i try higher ISO, dimmer flash lights. whereas Caucasian girls (usually with smoother skin than men) producer nosier quality. and Chinese man produces an obviously even noiser result, while chinese young girls produces worst very noisy results. An exception is if i scan a chinese elderly, which producer really nice details with least noise.

reading and trying myself about how Pscan works, i thin kit definitely has to do with different level of skin contrast/ pattern clarity, etc.

i must say visually the causian men scans can withstand full screen head with pleasant looking detail/low noise, while the chinese girls i have to zoom out up to only 1/3 of screen in order to have same "visual quality". such a huge difference.

Then i tried projecting noise pattern (which i need to use lower ISO and wider aperature, slower shutter, sacrifice texture, not ideal), results:
the already high quality Caucasian men scans do not gain significant higher quality results, while others gain increasing level of detail/lower noise, from cauasian girl < chinese men < chinese girls. the latter ones gain huge quality difference and catch up with the caucasian men scans. and this results catch up with the above flash only quality.

but there comes another frustration of acquiring usable texture...

this frustrates me, because i wish to test scan friends of different nationality. While my caucasian men friends are all good without projection noise, others are suffer lower quality, especially chinese groups scans are unacceptable quality without projection.

I tried splitted scan (but i have to manually switch off the flash at the time of projection, and change settings from smartshooter to send to the 12 cameras. this manual work takes me at least 3 seconds , and i suppose this is totally not ideal to ask the subject ot stay still for 3 seconds or above to introduce movement.

i have read this thread repeatedly :
http://www.agisoft.ru/forum/index.php?topic=1324.0
and yet i cant find an ideal way...

any advises?

thanks

18

General / Re: Strobe-based Image Projection

« on: November 06, 2013, 10:19:43 AM »

seems light there are people trying to experimenting it.
but LB alone cant have enough coverage unless u use multiple from multiple angle.
my thought is to add LB noise on top of existing studio strobe setup, so the light coverage is better and i can use soft light and or cross polarization altogether

any one has successfully use light blaster together with studio strobe as either source light, and/or, with studio strobe flashing together while still maintaining comparable light intensity for correct exposure?

19

General / Re: Strobe-based Image Projection

« on: November 05, 2013, 06:53:22 PM »

hi,
after reading this posts, i bought 2 light-blasters.

however, i found that i need studio strobe instead of small on-camera flash, in order to have comparable power to other lights, for the projection. the problem is light blaster can only fit small on-camera flash and studio strobe version do not have any release date.

does anyone successfully use light blaster? or any other successful case of flash projection highly appreciate if you can share your setup even its another solution

my two lightblaster is just not working here... i even ordered my custom-made slides and lens/filter for it...

thanks

20

Face and Body Scanning / Re: cross-polarization

« on: October 28, 2013, 05:44:38 PM »

thanks for the advises. 

im using CPL on cameras. from its name i guess it means circular. the polarizing film is linear according to the spec. so web site said it both linear and CPL did the trick and just that CPL is more modern coating. i also doubt this so the test i did was to have the film placed in front of the light and the CPL in front of my eye/camera. rotate the CPL to a certain angle, yes it becomes completely black and i cannot see the light behind the film. so i assume my materials works.

however, as mentioned before, if my eye/camera is not directly looking at the light (as in the test) but on a subject that reflect the light. (as in all cross-polar example i saw on web), i still have no way to completely filter them no matter which angle i try.

i have googled and read through the light stage which involve cross-polarization but it didn't say in detail how it set it up.

the light stage seems use the same setup of cross-polar and the lights are from all directions, so i doubt there is a limited range of light angle as discussed above. and there should be a way to really effectively eliminate all reflection.

anyone have some insights?

21

Face and Body Scanning / Re: cross-polarization

« on: October 27, 2013, 06:23:47 PM »

Thanks for the advise.

Im thinking to go diffuse reflected strobe off the walls and only place CPL on my cameras to cut a certain portion reflection out.

but im thinking of head scans since its less freeform than body poses, easier to control in small fixed region, and reflection on such closeup is a constant issue - im thinking if using cross polarization is good for this case.

if so, what will be the suggested setup to archive cross polar as well as most even lighting possible? lights direct illuminating from North-west-south-east? what do you mean by 45 degree to camera?

moreover, i tested that if i do cross-polar with camera(or eye viewing) directly pointing to the light. it works by being nearly dark for normal lights, and cut out 70-80% for strobes. so the Cross-polar working is confirmed, but now we need to to cut reflections instead of direct light. I cant get the exact theory understood becasue i imagine even lights coming out fr strobes polarized in one direciton. when reflected, it should be polarized in another direction and hence making the 90 degree orientation of camera CPL irrelevant. and i suspect thats why my cross-polar setup still wont cut all the reflection. see if anyone have an insight on this? is your 45 degree sugguestion relevant to this?

thanks

22

Face and Body Scanning / cross-polarization

« on: October 27, 2013, 04:47:03 PM »

hi

im experimenting a studio setup of fullbody scan.
i read some web site about cross polarization.
does someone have a detail suggestion on how it can be done properly to give 99% diffuse photos?
1) i try to put the polarizing films on the strobe and camera(with 90 degree rotated direction), however i still got some 40% specular reflection remains. the strobe is directly pointing to the subject. i'd like to check whats done wrong
2) obviously direct pointing the strobe to subject will produce harsh undesirable shadows.  before i come across cross polarization, i used to point the strobe to the white walls and make it a large reflector. can cross polarization works if reflected/diffuse lights like this is used?
 
thanks
viper

23

Feature Requests / Re: Command line access and Python scripting

« on: October 27, 2013, 10:05:52 AM »

i second that. it could be a motivation for us to consider purchasing pro version. I was wondering why this feature was dropped like about a year ago?

viper