Building a mult-camera rig - page 14 - Hotwire! Hardware Mods, Accessories and Insights - CHDK Forum

Building a mult-camera rig

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Can you recommend on a way how to align all cameras ? height / fov / angle ?


Ported :   A1200    SD940   G10    Powershot N    G16

Ported :   A1200    SD940   G10    Powershot N    G16

Re: Building a mult-camera rig ...... (and way how to align all cameras)
« Reply #134 on: 23 / July / 2014, 00:26:27 »
Can you recommend on a way how to align all cameras ? height / fov / angle ?
The "Simple" Multi-Camera "Alignment" answer is here.

CHDK PTP multiple instances; Reply by H-H #31 on: 17/September/2013

You just need three ping-pong or tennis balls, suspended, on a fishing line,
at the geometric center of your Multi-Camera Array.

And  Reply #45 on: 18/September/2013, the alignment Graphic is here.;topic=8769.0;attach=9068

Your Multi-Camera Array has its Maximum Parallax in the, fixed, Horizontal Plane.

You then, simply, "Align" your Multi-Camera Array for Minimum Parallax in the Vertical Plane, located at
the arrays geometric center.

The "Complex" Multi-Camera "Alignment" answer is here.  ( ??? )

Image Alignment and Stitching: A Tutorial
by Richard Szeliski Microsoft Research, USA,

~~~~"sparse set of features"~~~~ OR JUST ===="three ping-pong balls"====

"...While most of the above techniques work by directly minimizing pixel-to-pixel dissimilarities, a
different class of algorithms works  by extracting a sparse set of features and then matching these
 to each other [7,30,35,38,129,227]..."

"....Feature-based approaches have the advantage of being more robust against scene movement
and are potentially faster, if implemented the right way...."
"....Their biggest advantage, however, is the ability to “recognize panoramas,” i.e., to automatically discover the adjacency (overlap) relationships among an unordered set of images, which makes
them ideally suited for fully automated stitching of panoramas taken by casual users..."

~~~~"if implemented the right way"~~~~ OR ~~~~by using A_I_S 2014~~~~


"A_I_S ... is particularly useful for this process since it allows sub-pixel alignment...."

The ===="three ping-pong balls"==== give you the  three, "COMMON", control points. [3 x 24 C.P's]

The "Anchor Image", is an Absolute Image, and NOT a series of Relative Images.
The "Anchor Image" is "COMMON" and "ALWAYS" linked "ALL" other Images.
The Minimum number of control points required is "TWO". [2]
The Maximum number of control points required is "THREE". [3]

The number of, optional, control points, between adjacent images is THREE. [3]

[r]  Optimize "Roll" Angle of the camera position.

[-X] Optimize "X" Coordinate of the camera position.

[-Y] Optimize "Y" Coordinate of the camera position.


[-v ] Verbose, print progress messages

[-z = 0] Optimize "Z" coordinate of the camera position. Useful for aligning more distorted images.

[-f HFOV] Approximate horizontal field of view of input images, use if EXIF info not complete.

[-l] Assume Linear Input Files.

~~~These, Always Set to Zero~~~~

Rectilinear, when the cameras in the array are set perpendicular to Horizontal Plane
and tangential to the rigs camera mounting ring.

[p] Pitch is ZERO (0)  (Unselected)

[y] Yaw is  ZERO (0)  (Unselected)


Hugin GUI treats Image Stacks as Panoramas.   ( ??? )

Align_Image_Stack "Roll" Angles can, very quickly, become corrupted.  ( ??? )

Camera alignment is only done once and only realigned if the rig is changed.

The Align_Image_Stack, Alignment Data, is common to all the Multi-Cam rig images.


« Last Edit: 23 / July / 2014, 01:41:34 by Hardware_Hacker »

Batteries - done (!!!!)

Now, waiting to get the cameras (should arrive every day) including  USB remote relay,& Wireless relay switch and quick power plug

Hope to be ready on weekend for dry run .....

Will update

Hi all

Yesterday we had the first dry run , everything was connect, powered and ............... It failed :(

Here is list of the problems we faced

1. Drivers - we needed to install the libusb driver for every camera ( 24 cameras ) , it is time consuming !!!! On camera at time.... - Done

2. Power - we are using 4 USB hub to connect 24 cameras , 6 cam's per hub. The 4 USB hubs connect to main USB hub ( same hardware just aggregating all USB cables ). Main USB  connects to the laptop .
We found that after 10 th camera the 5 volt drop and the cameras started to shoot without control ....... We believe we will need to power the USB hubs with external power supply. - Open issue

3. Procedure - we found that it crucial to first connect the laptop to the USB hubs and only than turn on camera by camera , otherwise it failed to recognize the cameras.
Is there limitation on number of cameras connected to laptop ?
Also , it seems that it isn't robust solution , we need to turn off / turn on cameras in order to recognize it. Have someone experienced similar issues? It will help to understand how to solve this . - Open issue.

I'd bet a lot of money that you will need to power those hubs. That's just a simple question of the limited amount of power available from your computer's USB port.
Ported :   A1200    SD940   G10    Powershot N    G16

Am I right about the procedure ? Is it the way to turn the cameras ?

Am I right about the procedure ? Is it the way to turn the cameras ?
I don't know. It might be related to the unpowered hubs? What happens if you connect  just four cameras directly to the master hub? And does it make a difference if it is powered?
Ported :   A1200    SD940   G10    Powershot N    G16


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