Date   

Re: Better camera mounting on dual bars

gl
 


On 11/02/2021 12:02, George Themelis wrote:

I am an expert in twin camera mounting. (no, seriously, I have more twin camera mounts than probably anyone else, and have tried twin cameras of all sizes in all different configurations).


I know that's true, thanks for the insight.

 It is difficult to see what is going on in your picture. There are a lot of stuff attached to the bar and something at the top of the cameras?


OK so it's two bars like this (I think that's the actual bar):
Neewer 8″/20.3cm Dual Camera Mount Tripod Bracket for: Amazon.co.uk: Camera & Photo0

They are attached below (traditional) and also above the cameras (those cameras also have mounting points on top).  I figured that would make the rig more rigid also help with alignment.  But it also means there is rubber below _and_ above, causing even more 'give' in the camera alignment.

FYI the stuff behind is a genlock generator, and a large 12V LI-on battery that powers everything (for hours).  And there's my own circuit on top for remote control and LED feedback (eg. showing successful genlock sync).  And a screw-in handle.

 I remember that you are using wide angle lenses and I wonder what kind of misalignment you see. I assume it is vertical. If you are having problems with wide angle lenses, imagine using 600mm lenses like I do :)


Yes they're wide (~76deg HFOV, don't have the 35mm equivalent focal length to hand) and the error is vertical, and also very slightly rotational, due to (I think) the give in the rubber.  And I'm happy with the FOV : )  (I've actually just bought even wider lenses, though they haven't arrived yet).

 You can remove the rubber friction pads but then you will have no friction and your cameras will easily twist sideways (horizontal mis-alignment). You can try a different type of friction pads. You can even try some type of tape that will give you some friction but would be very thin.


Good point, the rubber is not just about scratch protection!  Yes so a thin non-slip tape or similar is worth a try.  I think the important thing is just to get rid off the rubber, which even with the bars fully tightened still gives a little, meaning that I can twist the cameras and actually resolve the vertical error.   But it's kinda unreliable and wastes time.  Plus they easily out of alignment again once you move them to the next shot.

I am a big fan of the Jasper Engineering products. <snip>  They also made vertical bars with convergence control. None of these really apply to your situation.

Ah right, so that one didn't allow for vertical or even rotational adjustments?  I remember reading about something many years ago, but maybe it wasn't that advanced.  Has anyone ever made something like this?  I'm picturing a mounting platform with eg. 3 fine adjustment screws for minor adjustments in each axis.

Of course a DIY solution might be all I need.
--
gl


Re: Better camera mounting on dual bars

Etienne Monneret (Perso)
 

Le 11/02/2021 à 13:25, Etienne Monneret (Perso) a écrit :
If I'm right:
- a lens shift doesn't introduce keystone (perspective trapezoidal deformation), it should thus be comfortable to apply a simple post treatment with a X/Y alignment (just loosing small surrounding bands).
- if you manually tune the physical camera position to fix the bad alignment, you will introduce a keystone, harder to fix with a post treatment.

I think I have a procedure, usable if you do not have fish-eye distortions, to know what kind of problem you have:

  1. display a grid on your screen (for example 30 horizontal lines + 30 vertical lines)
  2. take a stereo picture of your screen, paying a big attention to get it as perfectly square as possible (to get as vertical lines as possible and as horizontal lines as possible)
  3. try to mount your stereo with simple X/Y alignment
  4. if you succeed in aligning both grid together (even if lines are not perfectly vertical or horizontal) you have a lens shift problem. If you do not succeed in aligning both grid together, staying with not-matching keystones, you have a camera positioning problem.

;-)



Re: Better camera mounting on dual bars

Laurent DOLDI (Toulouse, France)
 

On Thu, Feb 11, 2021 at 05:19 AM, gl wrote:
The main problem seems to be the classic rubber protectors rings on the mounts.  They're too inaccurate, I can wiggle the cams into better alignment, but they don't stay there too long due to the uneven rubber beneath them
I had the same problem with this bar for my Sony RX100 pair:
https://www.amazon.fr/gp/product/B00PAG93ES
Neewer Support de trépied pour Appareil Photo stéréo 3D 20,3 cm

So I removed the rubber rings, and replaced the screws by shorter ones. I plan to add thin rubber or tape on the bar to avoid the cameras moving if the screws are not tightened hard.
 


Re: Better camera mounting on dual bars

George Themelis
 

Here is a picture of my Sony RX10 twin camera rig.

 

I found that the vertical orientation is the only way for me to control alignment at the 600mm (equivalent focal length) end and still have a portable rig that I can carry around and use hand held (no tripod or monopod) and shoot birds and wildlife. Plus, I compose my pictures in 3D, can see the alignment, stereo window, etc.

 

The only item of concern to you is the Japer bar. It is short like yours, thicker, maybe the platform is wider, it uses friction “tape” (not rubber) and two large mounting screws. It works very well.

 

The two vertical posts can rotate (if I do not tie the screw too tight) and this gives me convergence (horizontal) control. I usually fix the right camera and converge the left with one hand as I look through the viewfinder. Convergence needs to change as the distance of the subject changes.

 

The cameras are mounted to the vertical posts using a mini panoramic head. This allows me to adjust / correct the vertical orientation. I zoom all the way to 600mm, point to a target, align the cameras, then tighten the screws. If I bump the camera or change batteries, then I need to realign, not a big deal. This is a late addition, at first I was just twisting the cameras, but because the are tightly mounted, this twisting damaged the rubber/friction pad of the vertical posts, plus it was not very accurate. The panoramic heads are small and work well for my application.

 

George

 

From: George Themelis via groups.io
Sent: Thursday, February 11, 2021 7:03 AM
To: main@photo-3d.groups.io
Subject: Re: [Photo-3d] Better camera mounting on dual bars

 

I am an expert in twin camera mounting. (no, seriously, I have more twin camera mounts than probably anyone else, and have tried twin cameras of all sizes in all different configurations).

 

It is difficult to see what is going on in your picture. There are a lot of stuff attached to the bar and something at the top of the cameras?

 

I remember that you are using wide angle lenses and I wonder what kind of misalignment you see. I assume it is vertical. If you are having problems with wide angle lenses, imagine using 600mm lenses like I do :)

 

You can remove the rubber friction pads but then you will have no friction and your cameras will easily twist sideways (horizontal mis-alignment). You can try a different type of friction pads. You can even try some type of tape that will give you some friction but would be very thin.

 

If your problem is vertical alignment (not horizontal) then there are really no easy solutions. You can try using a shim under the camera that is directed lower, and try to raise it a bit.

 

I am a big fan of the Jasper Engineering products. They may nice, substantial twin camera bars (similar to the one you are using, but better quality). Jasper Engineering made bars with sliding platforms. They also made vertical bars with convergence control. None of these really apply to your situation, except for the very simple, high quality short twin bar that looks similar to yours but a bit thicker. This one has some kind of friction pad and does not use rubber like yours, so it will be better (if you can find one, I have a couple :))

 

George

 

 

 

From: gl
Sent: Thursday, February 11, 2021 6:19 AM
To: Photo-3d@groups.io
Subject: [Photo-3d] Better camera mounting on dual bars

 


I've got a traditional cheap dual-camera mounting bar for my dual Micro Cinema Camera rig.  In fact I use two bars, one above & one below the cameras (they have 1/4" mounting points on both sides) for stability:

This works fine, and I almost never change my stereo base (the smallest I can get).  But the alignment is always a bit out.  I can easily correct that in post, but it would be better if I could optimise it on the mount, and that's especially important for future live streaming where I can't correct alignment.

The main problem seems to be the classic rubber protectors rings on the mounts.  They're too inaccurate, I can wiggle the cams into better alignment, but they don't stay there too long due to the uneven rubber beneath them.

So first, how about getting rid of the rubber and instead just putting tape on the brackets to minimimse scratching that way?  That should give a tight mount right against the metal.  Anyone done that?

Also I remember reading here many years ago that someone (was it Jasper Engineering?) had created a bar that had special fine adjustments on the mounts so that the cameras could be very precisely aligned.  I believe that bar was discontinued a long time ago, but is anything like that still available?

The catch is that I use the smallest IA I can (around 8-9com), and usually don't need to change it, so I use the shortest dual bracket.  Everything is about compactness and low weight on my rig, so a large/heavy bar just for that ability wouldn't make sense.

Or are there individual adjustable mounts like that that can be added on top of a standard 1/4" bracket?
--
gl

 

 


Re: Better camera mounting on dual bars

Etienne Monneret (Perso)
 

Le 11/02/2021 à 12:19, gl a écrit :
But the alignment is always a bit out.
Can you share a raw stereo picture showing that bad alignment, to get a better idea on it?

I'm not an expert of such things, but on my own experiment, I think the bad alignment is due to a kind of lens shift, rather than the bar itself:

http://www.3denlive.com/doc/wiki/index.php?title=Low-cost_stereo_camera

If I'm right:
- a lens shift doesn't introduce keystone (perspective trapezoidal deformation), it should thus be comfortable to apply a simple post treatment with a X/Y alignment (just loosing small surrounding bands).
- if you manually tune the physical camera position to fix the bad alignment, you will introduce a keystone, harder to fix with a post treatment.

The problem is more complicated when this lens shift is combined with fish-eye distortions. The fish-eye distortion center is shifted, introducing differences between left and right image really similar to a keystone. It's then a bit tricky to mount the stereo pictures: it needs a proper lens correction calibration, with different values for left and right images.

Just my current analyze, but not really sure all this is completely true.

;-)


Re: Better camera mounting on dual bars

George Themelis
 

I am an expert in twin camera mounting. (no, seriously, I have more twin camera mounts than probably anyone else, and have tried twin cameras of all sizes in all different configurations).

 

It is difficult to see what is going on in your picture. There are a lot of stuff attached to the bar and something at the top of the cameras?

 

I remember that you are using wide angle lenses and I wonder what kind of misalignment you see. I assume it is vertical. If you are having problems with wide angle lenses, imagine using 600mm lenses like I do :)

 

You can remove the rubber friction pads but then you will have no friction and your cameras will easily twist sideways (horizontal mis-alignment). You can try a different type of friction pads. You can even try some type of tape that will give you some friction but would be very thin.

 

If your problem is vertical alignment (not horizontal) then there are really no easy solutions. You can try using a shim under the camera that is directed lower, and try to raise it a bit.

 

I am a big fan of the Jasper Engineering products. They may nice, substantial twin camera bars (similar to the one you are using, but better quality). Jasper Engineering made bars with sliding platforms. They also made vertical bars with convergence control. None of these really apply to your situation, except for the very simple, high quality short twin bar that looks similar to yours but a bit thicker. This one has some kind of friction pad and does not use rubber like yours, so it will be better (if you can find one, I have a couple :))

 

George

 

 

 

From: gl
Sent: Thursday, February 11, 2021 6:19 AM
To: Photo-3d@groups.io
Subject: [Photo-3d] Better camera mounting on dual bars

 


I've got a traditional cheap dual-camera mounting bar for my dual Micro Cinema Camera rig.  In fact I use two bars, one above & one below the cameras (they have 1/4" mounting points on both sides) for stability:

This works fine, and I almost never change my stereo base (the smallest I can get).  But the alignment is always a bit out.  I can easily correct that in post, but it would be better if I could optimise it on the mount, and that's especially important for future live streaming where I can't correct alignment.

The main problem seems to be the classic rubber protectors rings on the mounts.  They're too inaccurate, I can wiggle the cams into better alignment, but they don't stay there too long due to the uneven rubber beneath them.

So first, how about getting rid of the rubber and instead just putting tape on the brackets to minimimse scratching that way?  That should give a tight mount right against the metal.  Anyone done that?

Also I remember reading here many years ago that someone (was it Jasper Engineering?) had created a bar that had special fine adjustments on the mounts so that the cameras could be very precisely aligned.  I believe that bar was discontinued a long time ago, but is anything like that still available?

The catch is that I use the smallest IA I can (around 8-9com), and usually don't need to change it, so I use the shortest dual bracket.  Everything is about compactness and low weight on my rig, so a large/heavy bar just for that ability wouldn't make sense.

Or are there individual adjustable mounts like that that can be added on top of a standard 1/4" bracket?
--
gl

 


Better camera mounting on dual bars

gl
 


I've got a traditional cheap dual-camera mounting bar for my dual Micro Cinema Camera rig.  In fact I use two bars, one above & one below the cameras (they have 1/4" mounting points on both sides) for stability:

rig

This works fine, and I almost never change my stereo base (the smallest I can get).  But the alignment is always a bit out.  I can easily correct that in post, but it would be better if I could optimise it on the mount, and that's especially important for future live streaming where I can't correct alignment.

The main problem seems to be the classic rubber protectors rings on the mounts.  They're too inaccurate, I can wiggle the cams into better alignment, but they don't stay there too long due to the uneven rubber beneath them.

So first, how about getting rid of the rubber and instead just putting tape on the brackets to minimimse scratching that way?  That should give a tight mount right against the metal.  Anyone done that?

Also I remember reading here many years ago that someone (was it Jasper Engineering?) had created a bar that had special fine adjustments on the mounts so that the cameras could be very precisely aligned.  I believe that bar was discontinued a long time ago, but is anything like that still available?

The catch is that I use the smallest IA I can (around 8-9com), and usually don't need to change it, so I use the shortest dual bracket.  Everything is about compactness and low weight on my rig, so a large/heavy bar just for that ability wouldn't make sense.

Or are there individual adjustable mounts like that that can be added on top of a standard 1/4" bracket?
--
gl


Re: Stereopix ROOMS YouTube Video #ROOMS

Paul Thoele
 

Just connected my old 3D-TV (Interlaced Modell) to the Net for using it as a big screen in Jitsi Meetings with ROOMS for the 3D-Pictures.

Used a Raspi Pi 4 with Ubuntu Mate 20.10 for the Network connection.

Spend some time with the TV to fix the https://en.wikipedia.org/wiki/Overscan problem.

Testing ROOMS was successful using FireFox on the Raspi.

Thanks for the new "Reverse" and "Forward" botton in the ROOMS Presenter screen.

Can now watch also this interlaced pictures https://www.fotocommunity.de/spezial/pol-und-kmq/14724 on the old 3D-TV in Full-Screen Mode.

Regards
Paul


Re: 3D Image Creation Software

 

OK -- everybody please stop. As a fellow developer I thought this was an interesting and valuable thread. But I'll be forced to put this thread under moderation if this off-topic bickering continues. Thanks to all for your cooperation and restraint.

Bill Costa Co-Moderator.


Re: 3D Image Creation Software

 

No comment to Francois then?
It would appear that it is permitted for some to accuse others of rudeness or to sidetrack the conversation by giving social guidance, but responding to them results in a slapdown. I think George Orwell summed that attitude up nicely: “Everyone is equal but some are more equal than others.”


Re: 3D Image Creation Software

 

May I suggest that you make the same suggestion to the other participant in the discussion?

On 10/02/2021 8:14 pm, Etienne Monneret (Perso) wrote:
Le 10/02/2021 à 20:34, ChrisOfBristol via groups.io a écrit :
Actually it is you that is getting offended, the rest of us have just got on with the technical topics. I didn't reply to the rest of your post as I wasn't interested in your "guidance". Are you a moderator - or just a wannnabee one?
Please, stop over-focusing on that stupid discussion without any interest for the community, and exchange about stereo picture and technical subject.






Re: 3D Image Creation Software

Etienne Monneret (Perso)
 

Le 10/02/2021 à 20:34, ChrisOfBristol via groups.io a écrit :
Actually it is you that is getting offended, the rest of us have just got on with the technical topics. I didn't reply to the rest of your post as I wasn't interested in your "guidance". Are you a moderator - or just a wannnabee one?
Please, stop over-focusing on that stupid discussion without any interest for the community, and exchange about stereo picture and technical subject.


Re: 3D Image Creation Software

 

Actually it is you that is getting offended, the rest of us have just got on with the technical topics. I didn't reply to the rest of your post as I wasn't interested in your "guidance". Are you a moderator - or just a wannnabee one?

On 10/02/2021 7:28 pm, Depthcam via groups.io wrote:
On Wed, Feb 10, 2021 at 09:20 AM, ChrisOfBristol wrote:
I do object to being told by Francois that 'This is not about being "polite or "rude"', "the people that have been responding to you are highly experienced" I do not like being patronised.

You seem to take offense quite easily - that evidenced by the fact you singled out that one sentence in my post and ignored everything else.  You also mentioned "being reported" as something to which you took offense until you realized that you had misunderstood what was said.  When I said "it is not about being polite or rude", it's not about "who said it first ?".  It's simply about the fact that you arrived here just recently, are unknown to us and yet come across as one who is very sure of himself against people whose experience has been demonstrated to the community over many years.

So I point out again that it would help if you were to tell us a bit about your background such as how long have you been involved in stereo photography and which 3D programs did you try before attempting to design your own.

Francois



Re: 3D Image Creation Software

Depthcam
 

On Wed, Feb 10, 2021 at 09:20 AM, ChrisOfBristol wrote:
I do object to being told by Francois that 'This is not about being "polite or "rude"', "the people that have been responding to you are highly experienced" I do not like being patronised.

You seem to take offense quite easily - that evidenced by the fact you singled out that one sentence in my post and ignored everything else.  You also mentioned "being reported" as something to which you took offense until you realized that you had misunderstood what was said.  When I said "it is not about being polite or rude", it's not about "who said it first ?".  It's simply about the fact that you arrived here just recently, are unknown to us and yet come across as one who is very sure of himself against people whose experience has been demonstrated to the community over many years.

So I point out again that it would help if you were to tell us a bit about your background such as how long have you been involved in stereo photography and which 3D programs did you try before attempting to design your own.

Francois


Re: 3D Image Creation Software

Etienne Monneret (Perso)
 

Le 10/02/2021 à 18:07, ChrisOfBristol via groups.io a écrit :
"In stereo, small image damages are much more sensible [perceptible] than with simple 2D pictures" I didn't realise that, but it makes sense because they would confuse the brain, which is always an uncomfortable feeling.

It's also because the 3D perception is a result of several factors. When viewing a stereo picture, you are providing with the parallax information. But, it's only one information, while some others are lacking, like the focusing distance (all being at the screen distance). Managing the illusion is hard. Any kind of disturbing problem is breaking the magic effect. Even the parallax itself is often not perfect, depending on the shooting conditions.



Re: 3D Image Creation Software

 

Some of the other answers are probably more technical than I need, I'll return to have a look at them when I've got time, as it's useful to understand the underlying issues.

However JackDesBwa's post and yours are the most useful, as they are more to the level of what I need, I'll have a look at the links. If possible I would hope to include this in the next release.

"In stereo, small image damages are much more sensible [perceptible] than with simple 2D pictures" I didn't realise that, but it makes sense because they would confuse the brain, which is always an uncomfortable feeling.


On 10/02/2021 3:52 pm, Etienne Monneret (Perso) wrote:
Le 10/02/2021 à 16:20, ChrisOfBristol via groups.io a écrit :
I intend to make all the changes recommended by the various contributors and am now studying the more technical issues relating to fringing. I don't understand enough of it yet to even ask a sensible question, but this thread is clearly a source of considerable expertise and I will no doubt return to it when I have something useful to say.

As said by JackDesBwa, if you are using Pillow to save your anaglyph picture to a JPG file, you simply need to add a "subsampling" parameter with the "4:4:4" value in your call.

https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.save

https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html#jpeg

That's all.

You won't get any JPG compression ghosting in your anaglyphs after that (except with very strong compression rates, but it's of no real interest).

As JackDesBwa suggested, you may also set a quality higher than the default one (thus a lower compression rate). It will bring you with file a bit larger (in Kb), but it can be useful to get much nicer anaglyphs. In stereo, small image damages are much more sensible than with simple 2D pictures.

;-)









Re: 3D Image Creation Software

Etienne Monneret (Perso)
 

Le 10/02/2021 à 16:20, ChrisOfBristol via groups.io a écrit :
I intend to make all the changes recommended by the various contributors and am now studying the more technical issues relating to fringing. I don't understand enough of it yet to even ask a sensible question, but this thread is clearly a source of considerable expertise and I will no doubt return to it when I have something useful to say.
As said by JackDesBwa, if you are using Pillow to save your anaglyph picture to a JPG file, you simply need to add a "subsampling" parameter with the "4:4:4" value in your call.

https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.Image.save

https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html#jpeg

That's all.

You won't get any JPG compression ghosting in your anaglyphs after that (except with very strong compression rates, but it's of no real interest).

As JackDesBwa suggested, you may also set a quality higher than the default one (thus a lower compression rate). It will bring you with file a bit larger (in Kb), but it can be useful to get much nicer anaglyphs. In stereo, small image damages are much more sensible than with simple 2D pictures.

;-)


Re: 3D Image Creation Software

 

Etienne, I have no problem with your comments about my software, I find constructive criticism very helpful. However there was a bit of a hiccough when you accused me of being rude. That was a bit much considering I had simply replied to your comments in a similarly concise manner - hence my response. For example in one of your comments you started a sentence with “I reported you...” this gave me quite a shock, because to me that meant that you had made a complaint to someone in authority about me! When I had understood the rather confusing sentence I realised that you meant “I have made a report”. No problem, I can make allowances for people whose first language is not English and for their different writing styles. Our conversation then continued without problems and we have continued to discuss the technical issues constructively.

I do object to being told by Francois that 'This is not about being "polite or "rude"', "the people that have been responding to you are highly experienced" I do not like being patronised. I treat all people with respect and had realised that the commenters were expert and that you at least had authoured an application. We are quite capable of working these things out for ourselves and our conversation continued without problems after the initial hiccough.

I intend to make all the changes recommended by the various contributors and am now studying the more technical issues relating to fringing. I don't understand enough of it yet to even ask a sensible question, but this thread is clearly a source of considerable expertise and I will no doubt return to it when I have something useful to say.


Re: A Conversation with David Burder - Lenticular

Tim Goldsmith (Monark)
 
Edited

David at his most self deprecating best. He should write a book!

And not too bad for a Zoom virgin.


Re: 3D Image Creation Software

Etienne Monneret (Perso)
 

Le 10/02/2021 à 14:17, ChrisOfBristol via groups.io a écrit :
'This is not about being "polite or "rude"' I suggest you address this comment to the person who began that slant to the conversation.

To avoid any kind of misunderstanding: be sure you are welcome here, and all my comments were thought in the only goal to help you.

As I wrote on my own web site: "Feedbacks are always welcomed, and a happy user is always a reward for a software developer".

In other words: I much more prefer to be a bit rudely criticized, then having the possibility to improve my software, than facing a loud silence or an cumbersome indifference.

I always think it's the same for all other software developers...

;-)


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