Topics

16

Face and Body Scanning / Charging 50+ Cameras / Batteries

« on: January 21, 2014, 07:37:55 PM »

I was wondering how the studios with more than 30 (or less) cameras charge their batteries.   

- My cameras dont have support for external power supply so thats an issue, what came to my mind is that i could modify the batteries so they get the power from the main power source of the studio. Instead of having to charge all of them separately. Has anyone tried anything like this ? 

- Is there any comercial adaptor or "fake battery" so that it gathers the power from the wall plug ? 

17

General / Model is not on origin when importing

« on: January 20, 2014, 01:19:42 PM »

Dear all,

I ve imported my re-UV model and retopologized (from Zbrush) into agisoft, however the model is not on the original position so no texture can be generated.

- I know that the model shouldnt be moved, rotated or scaled on Zbrush. Im pretty sure i didn?t do this.
- Maybe im using something that is moving the model ? i dont understand it. 

Thanks!

18

General / Zbrush - Workflow

« on: December 20, 2013, 03:10:06 PM »

Ive read many workflows on how to use Zbrush, however despite my own tries i havent been able to fully complete it...

This may be offtopic to Agisoft however it is related to the data i get off agisoft.

- My main problem comes when Remeshing, the results are not very good:

1. Mesh looses a good amount of detail even setting target polygons count to 100
2. Some artifacts appear on the mesh

- UV Master simply doesnt work after this process, either it gives me a "error ocurred" or when i flatten the UVs nothing appears or some "artifacty" results


Is anyone experiencing something similar ?
Any tips ?

19

Feature Requests / Lo Minimization or Normal Bilateral filtering

« on: December 20, 2013, 12:11:08 PM »

http://faculty.cs.tamu.edu/schaefer/research/L0Smoothing.pdf

Agisoft is already an amazing software, but it would be even better if it had one of these algorithms 
It would be amazing to have this for mesh smoothing while preserving details.

20

Face and Body Scanning / Face scanner - Prototype

« on: December 11, 2013, 01:43:28 PM »

Dear all,

After many questions, doubts solved and problems addressed - Im very happy to share with you all my very first prototype of Stereophotogrammetry face scanner: 

- https://www.dropbox.com/sc/suy6fwejacnbn50/aSMR2CZQ4E -

--------------- Key features: -------------

* I really wanted it to be "cheap" although at the cost of not being totally instant (it takes 2 seconds to go from 40 degrees to 140 degrees (there are angle limitations for the body, security of the cameras etc)

* It is important that the subject doesnt move - for alignment purposes.

* The scanning is done with total darkness as of yet, every camera opens their shutter for 1/50, in between that time, the flashes are fired at 1/16intensity.

* The prototype has a inclinometer (acelerometer) sensor on the rotation axis (similar to the ones our mobile phones have to detect inclination. (its the blue box)

* When the inclinometer detects the programmed ? angle it sends the shutter signal to each of the cameras and flashes

---------- Details -----------

Pre-mirror up signals are sent so the camera's total shutter lag is decreased.

- Time between fully shutter mechanical operations is around 0,4 seconds. That is : The camera is not ready to shoot again until 0,4 seconds.
- Cameras are Canon 700d (i bought those ones because they had better FPS)
- Flashes are Yongnuo 560 iii
- Lenses are canon 1.8f 50mm
- The radius of the semi circumference is 80cm
- Distance between cameras is around 26cm

* For 6 programmed angles, the total shooting time is 2 seconds of scanning.
(shoots every 20 degrees) 6 times. That is : 36 photos. (Maybe i?ll add two more cameras), but no more.


------------------------------------- ISSUES ------------------------------------------------


In my opinion, the fact that the flashes are moving relative to the subject is not very good for feature detection

Subject movement is a problem of course, but if i do the movement within 2 seconds and the subject tries to stand still, alignment is done correctly.


-----------


I Would really love to read opinions, thoughts or critics of course! 
* I?ll keep this post up to date with any new tests, problems or results so that we can all share our experiences!

https://www.dropbox.com/sc/suy6fwejacnbn50/aSMR2CZQ4E

21

Face and Body Scanning / Type of pattern projection

« on: December 09, 2013, 06:57:26 PM »

Hello all,

I?ve finally made some improvements on my 3d scanning rig, the next step for me (at the same time as improving light conditions) is to develop a pattern projection.

So my doubts are the following:

1. What kind of noise projection should i use ? I know that SIFT algorithm tries to find "corners" so as little as possible squares would be very appropriate. But maybe noise(dots) pattern works best ? anyone had any experience with this ?

2. Im going to use a flash with a 35mm transparent slide and a lens to project the details onto the surface, however using this method i?ll loose my diffuse light conditions...
The problems are that:

- The projection has to be much more powerful than the default light conditions so i can achieve contrast... otherwise noise projection would be useless i suposse.
- I?ll have to lower the exposure of my flashes so the noise pattern projection flash fires with more intensity in comparison to the other flashes (this however, will kill my diffuse light)

How could i overcome this ?

- I?ve read that i could use laser with different patterns however this is dangerous for the eyes
- IR not an option ?
- UV maybe ?

Thank you for your always kind responses!
Manuel.

22

Face and Body Scanning / Face scanning and macro

« on: December 03, 2013, 01:40:36 PM »

I have some questions regarding to face scanning id love to discuss / share some thoughts about this with all of you:

- Ive recently made a first prototype with good scanning results, however it is too big at the moment. (it is a semi circular frame of 80 cm radius) with 6 cameras mounted onto it.
This is the source of my problem, i need this system to be smaller. So here go all my questions:

1. At the moment the cameras are positioned at 80cm from the subject so i get "proper" DOF (its around 17cm) lenses are 50mm prime. f13. Im using continuos light using high luminance fluorescents.

2. Since i need this system to be smaller, (like 50 cm radius for example) DOF will of course decrease.
I can probably stop down to f20 but difraction will blur my entire scan producing a low amount of matching points -> more noise.

3. 50mm lens allows me to focus at a minimun distance of 45cm so 50cm is OK, however this is not the main issue.

4. Ive calculated 80cm (which is the radius of this prototype) it is so to fill the frame of the sensor.
If i build a new one at 50cm the face will fill too much of the face leaving un-scanned parts. So i may have to change to 35mm lens.

5. The main problem i see here is the DOF, does anybody have experience / thoughts / ideas scanning with macro photography ? How could i overcome DOF ?

* Maybe playing with cameras focusing different parts of the face ?
* Maybe increasing the number of cameras focused at different / overlaping parts of the face ?

- Ill post a very quick preview of the 3d render i did before the prototype so you can understand better what im saying:

All ideas or thoughts are welcome!

Manuel Franquelo.

23

General / Different Lighting source for feature detection

« on: November 18, 2013, 02:47:07 AM »

Hello 

I have a question:

- If its okay for Agisoft to have 2 different images (for stereo photogrammetry measurements) with different lighting sources on the subject.
I guess this could affect the feature detection if the same "features" are in a different lighting condition, for example in one image light is coming from the zenith and on the other one its coming from the front.

Could anyone clarify this please?
Is this very critical ?

Thank you a lot,
Manuel.

24

General / Scanning sculptures of a facade

« on: September 25, 2013, 06:49:44 PM »

Dear all,

Im going to do a little project next week which involves scanning the back of sculptures on a facade that cannot be reached using structured light scanners (or maybe they can, but its a much slower process) I dont need extremely high resolution.

Ive thought of mounting two 5d's 50mm lens with two flashes on an horizontal rail. (Synced) acting as a stereo pair.

The sculptures dont have any visible features, at least NOT many, to my eye. So i may need to use projected noise pattern? In this case, i guess i can project any pattern. Is just a standard noise pattern good enough ? or are there better pattern for feature recogniziton ? how big should the pattern be in relation to the object?

Are there any benefits of using a stereo pair set up ? Its easier for math operations knowing the distance between each camera's i guess ? whats the recommended distance from camera to camera ? Ive read 6,37cm somewhere.. but on the OpenCV book i read that 12cm is recommended.


Manuel.

25

Face and Body Scanning / First Face Scan, need tips

« on: September 16, 2013, 01:15:00 PM »

Hello 


I'd be really gratefull if anyone could answer these questions:
Taking account that im using one camera for tests purposes, and different views :

- Does it matter if the subject moves slightly from the first photo, till the last photo ? (this is important)

- Can photoscan take advantage of a pre-set photo-order ? for aligning purposes, more or like the ptgui templates or position xml's.
- How many photo's are needed to reduce the noise till its merely noticeable ? using a canon 600d 100 iso 50mm lens
- I?ve read that you need atleast 3 cameras pointing 45 degrees - 90 degrees for accurate point depth calculation, anyone had any experience with the minimum number of cameras needed to scan a face with quite reasonable accuracy and noise ratio ?

Thanks in advance.

Manuel.

26

General / Artifacts / Noise on 3d Model

« on: September 10, 2013, 10:59:59 AM »

Hello,

Im getting some strange noise / artifacts on my 3d model, i dont know what may be the source of this.
-> i shot this white matte object using diffuse / constant lighting
-> Canon MarkII 50mm lens
-> Fixed camera position, rotating the object on a tripod. 36 photos.
-> (I used mask from background)

Settings: Mild
Quality: High
Geometry type: Sharp
No decimation

Any ideas ?

Thank you,
Manuel.