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Re: New 3D lens announced

John Clement
 

While much of this exposition is correct, there is one statement that is definitely not correct. “When adding two 45 deg mirrors to a half a lens, the entire incoming ray bundle is now parallel.”  Plane mirrors do not make ray bundles parallel, but convex mirrors can do this.  The mirrors effectively add more distance to the object which means the lens subtends a smaller angle with respect to the object, so some rays miss the lens, but they still are coming at an angle.

 

I am pleased that the discussion included the model of ray bundles rather than just the central rays.  The mirror system is essentially a periscope.  If you have a double lens 3D camera, adding a periscope to each lens effectively gives you exactly the same effect as if you had separated the lenses, but it also adds a little distance from the object.  However such a device added to a single lens is not the same.  The light from each side is predominantly using almost half of the lens, but this will be a small effect for a “perfect” lens.  The images on each side will have opposite geometric distortion on the flat sensor.  Since all lenses have distortion this will exacerbate it.  Actually dual lens 3D cameras also have distortion, just as our eyes do, but the most distortion is in the periphery so we do not notice it.  With a dual lens system the geometric distortion is similar horizontally across the image, but not identical.  However when looking at a 3D image we look at the distorted photo with the central vision.  But the small distortions are easily accommodated.

 

The old 3D cameras of the 1950s all had a little toe in which effectively set the window at 7 ft.  This could be done by having the lens slightly toward the center with respect to the film frame.  The Civil War era cameras were parallel and captured extra detail on the R in the R lens, while the more modern cameras capture extra detail to the L behind the “7 ft window” with the R lens.  This problem will also happen with a dual camera system unless you toe them in slightly.  It can be solved by judicious cropping, which is what the Civil War era photographers did when creating the 3D cards.

 

John M. Clement

 

 

I am impressed with the determination for making new 3d lenses....

I wish I could jump in, but too slammed with other life endeavors.

I have followed some of the thread...

A few insights that might be helpful.

The goal of using a standard camera and achieving two stereo images is appealing to many of us.  It allows use of current camera technology and solves the lens sync issue better than anything, except maybe for genlock.

 

The downsides of using a mirror adapter on a single 2d lens.

 

1)  the captured aspect ratio is not ideal, but with added prisms, this can be helped significantly, as seen in the TriDelta splitter from the 1970's.

 

2)  The effective f stop is greatly increased (as for aperture diffraction, but not light), as the fl remains the same, but the half aperture creates a higher effective f stop.  A dual lens mirror / prism system solves this issue.

 

3)  The camera fl must be a bit longer than normal as you can not fold the ray bundle with mirrors without vignetting.

 

4)  A 2d lens is designed for the incoming ray bundle to enter the spherical front element in a specific spherical format, both horizontal and vertical.  When adding two 45 deg mirrors to a half a lens, the entire incoming ray bundle is now parallel.  A 2d lens was not designed for parallel rays entering the front spherical surface.  Distortion is just one outcome of this mismatch. The amount of distortion depends on the 2d lens design.  An optical ray trace from subject to target (sensor) must be utilized to determine which lenses are less problematic for this use.   The old lens splitters Francois referenced solved this problem by utilizing 2 lenses specially designed to accept the parallel ray bundle.  It's hard to fathom that the recent Canon patent discussed on this forum is the first advancement since those 1940's mirrored approach Francois referenced.  Canons designed solved all these optical issues, however, the aspect ratio issue might still exist, although I suspect they will flip the images with prisms to end up with two horizontal images vs. vertical. 

 

Outside of the future canon stereo splitter lens, the only other modern approach I have considered to this problem is using dual 2d camera lenses (interchangeable), which project on a fiber optic plate, then onto prisms which brings the dual imagery into the same aspect ratio of the sensor to prevent any pixel waste.   On the 2d camera, you photograph the fiber optic plate with a marco lens at proper magnification to assure the fiber optic plates contents ends up on the full sensor with close to zero waste.  While this is a very feasible but high tech solution, the cost of the fiber optic plates is extremely high...then add in optics, housing, prisms, design cost, etc., the product becomes ultra costly without high volume to amortize the costs.  Since Canon is more experienced with optical elements and prisms, their design is the best chance of a modern version of the 1940's 3d splitters.

 

BTW, a line diagram is not an optical ray trace.  So it will not determine the distortions which will occur by changing the mirror angles.  The 2d lens design is half the variable which is being left out of the equation. 

 

We do see how incredibly effective bringing two images from far apart to closely spaced can be, just pick up a decent pair of binoculars for proof.  Most of this technology is within reach of a company that specializes in imaging optics.  This is basically what Canon is intending to build, hopefully.  Just hoping if they do produce such, it does not have a major flaw, such as not flipping the images, and we end up with tall images vs. wide. 

 

Bill G

 

 

 

On Sat, Apr 10, 2021 at 1:18 PM Antonio F.G. via groups.io <afgalaz=yahoo.com@groups.io> wrote:

On Fri, Apr 9, 2021 at 03:09 PM, Depthcam wrote:

> By the way, such mirror design could produce parallel shots if the angle of the mirrors were adjusted for that.

Actually, no.  This will only work if a  mirror adapter is mounted on a set of two lenses  - as is the case with the Leiz Stemar or the Zeiss Stereotar C.  When you mount a mirror adapter on a single lens and keep the optical axes parallel, each side is viewing one side of the scene - just as if there were no adapter. In order for a left and right image to be recorded of the same scene, the optical axes MUST be converged.

I was not sure about this, but nothing like making a drawing of a "perfectly" parallel mirror adapter, with mirrors exactly at 45°:

The rays from a point at infinity arrive in parallel to the mirrors, and they send them to the lens in parallel as well. Therefore the lens prints a single point in the sensor. This is exactly the same as if the mirrors were not there.

It seems that the way to get two separate L&R images of the point is to deviate the mirrors somewhat away from 45°.
But I am still not sure whether this implies necessarily convergence of the two optical axis (may need another drawing:-)

Regards
     Antonio


Re: New 3D lens announced

Oktay
 

My two lens with mirrors design is nearing the end.

If I'll have time to complete, I will be using it in one week.

Oktay


Zoom In VR - Let's Get Started!

 

Okay, kids, it's probably going to take a month or two to learn how to do this, so let's get started!

 


Re: New 3D lens announced

John Toeppen
 

The vertical height of objects that are further away will be smaller than objects directly in front of the lens.   This happens with normal vision as well as cameras and is due to perspective and is not distortion at all.  Each camera needs to look straight forward and each will have its own "fisheye" perspective.  One could argue that the eyes converge normally on the subject and not the far field (at infinity) but this does not come out well if this is done.  The only time that convergence worked for me was with macro work and that was due to the subject being cropped otherwise, somewhat hyper, and dictated by the size of the camera bodies.   I would zoom in sometimes to reduce the fisheye and narrow my base to reduce the hyper effect.  It is amazing how well shifting a single camera a small amount to shoot macros works.


Re: New 3D lens announced

Depthcam
 

On Sun, Apr 11, 2021 at 12:45 PM, Antonio F.G. wrote:
This site makes a nice review of mirror adapters for stereo. It claims that parallel optical axis are possible using mirrors:

Yes, of course it is possible.  My criticism refers very specifically to SBS converters for single lenses such as the Kula Deeper.  The Tri-Delta stereo converter from the early sixties (actually designed in the thirties) uses a prism and two mirrors to produce wider than high pictures and, because the images are recorded head to head, the keystone effect is parallel and can be corrected by tilting the camera slightly.


> But I would eagerly buy the Kúla Deeper if it were not discontinued. It is because I would like to give a stereo use to my Fuji X-M1 which is much much better camera than the NX1000's of my present rig.


You would be much better off getting a Tri-Delta adapter on the used market.

Francois


Re: New 3D lens announced

Depthcam
 

> the captured aspect ratio is not ideal, but with added prisms, this can be helped significantly, as seen in the TriDelta splitter from the 1970's.


Definitely.  My criticism applies specifically to SBS mirror converters for single lenses.  The Prism Stereo (Tri-Delta) converter designed by brothers Pompey and Marcus Mainardi sought to correct many of the shortcomings of the traditional SBS converter.  Marcus was an optics teacher and Pompey, a mathematics teacher.


> The effective f stop is greatly increased


This reminds me of another shortcoming of such adapters:  The central dividing line is directly affected by the aperture setting.  A larger aperture will result in more blending of the left and right images while a smaller aperture will produce a dark line between the images.  Therefore the choice of an aperture may not only be for DOF considerations but it also affects the blending of the left and right images.


> Canons designed solved all these optical issues,


The Canon design is a completely different "beast" as it replaces the single lens with two - just like the old Stemar or Stereotar C or like the modern Lumix 3D lens... But of course, an extremely more complex optical design.


> however, the aspect ratio issue might still exist  (...) Just hoping if they do produce such, it does not have a major flaw, such as not flipping the images, and we end up with tall images vs. wide.


Keep in mind that the Canon patent as well as the Izugar stereo lens (which is the subject of this thread) are designed solely for VR180 shooting and viewing and therefore record two circular images.  If a wider than high image is the goal, then substantial cropping will be needed, which is what Lumix does with its 3D lens.

Francois


Re: New 3D lens announced

Depthcam
 

On Sat, Apr 10, 2021 at 01:08 PM, Stereopix Net wrote:
Sorry, but this sub-thread started because you suggested that stereo converters for single lenses shall be avoided because they introduce opposite keystone distortion with their design inherently bad which is a no-go. Several messages responded that well used, it could give interesting pictures.

Again, I was looking at this from the angle of commercially-sold products that perpetuate the myth that such adapters produce great 3D "out of the box".  But opposite keystone distortion is far from the only reason to avoid such converters.

Let's again review them:
a) Such converters can only be mounted to long lenses therefore restricting the FOV
b) some of them (like the Stitz) are rather heavy and pull down the front part of the lens
c) Several modern lenses have front sections that rotate as they focus requiring the adapter to be realigned after focus
d) The narrow vertical images must be cropped further...
  • when keystone correction is applied
  • to remove the center blend strip
  • to create a stereo window
  • to remove vignetting artifacts
e) internal reflections can occur on the left or right image - something that may be very difficult (or impossible) to correct.

I think these are all good reasons to avoid this type of converter.  And the reason why I feel so strongly about this is that, when I started out with 3D in the early eighties, I saw some very attractive ads for the Stitz stereo converter.  It looked like a piece of very advanced technical hardware and was advertised as producing perfect 3D.  I could not wait to own one of these marvels of technology.  But it turned out producing pictures that were mostly unviewable.  What Kula does today is exactly the same:  Smooth misleading advertising that convinces a new generation that they have a device that produces perfect 3D.  It does not.

I have tested not only the Stitz converter but also the Pentax, the Franka and the 3D World converters - all the same basic SBS design and all flawed.

Francois


Re: New 3D lens announced

Depthcam
 

On Sat, Apr 10, 2021 at 03:18 PM, Antonio F.G. wrote:

The rays from a point at infinity arrive in parallel to the mirrors, and they send them to the lens in parallel as well. Therefore the lens prints a single point in the sensor. This is exactly the same as if the mirrors were not there.


My point exactly !

Francois


Re: New 3D lens announced

Antonio F.G.
 


> By the way, such mirror design could produce parallel shots if the angle of the mirrors were adjusted for that.
Actually, no.  This will only work if a  mirror adapter is mounted on a set of two lenses  - as is the case with the Leiz Stemar or the Zeiss Stereotar C.  When you mount a mirror adapter on a single lens and keep the optical axes parallel, each side is viewing one side of the scene - just as if there were no adapter. In order for a left and right image to be recorded of the same scene, the optical axes MUST be converged.
This site makes a nice review of mirror adapters for stereo. It claims that parallel optical axis are possible using mirrors:
https://www.lockhaven.edu/~dsimanek/3d/stereo/3dgallery16.htm

Regards
     Antonio


Re: New 3D lens announced

Bill G
 

I am impressed with the determination for making new 3d lenses....
I wish I could jump in, but too slammed with other life endeavors.
I have followed some of the thread...
A few insights that might be helpful.
The goal of using a standard camera and achieving two stereo images is appealing to many of us.  It allows use of current camera technology and solves the lens sync issue better than anything, except maybe for genlock.

The downsides of using a mirror adapter on a single 2d lens.

1)  the captured aspect ratio is not ideal, but with added prisms, this can be helped significantly, as seen in the TriDelta splitter from the 1970's.

2)  The effective f stop is greatly increased (as for aperture diffraction, but not light), as the fl remains the same, but the half aperture creates a higher effective f stop.  A dual lens mirror / prism system solves this issue.

3)  The camera fl must be a bit longer than normal as you can not fold the ray bundle with mirrors without vignetting.

4)  A 2d lens is designed for the incoming ray bundle to enter the spherical front element in a specific spherical format, both horizontal and vertical.  When adding two 45 deg mirrors to a half a lens, the entire incoming ray bundle is now parallel.  A 2d lens was not designed for parallel rays entering the front spherical surface.  Distortion is just one outcome of this mismatch. The amount of distortion depends on the 2d lens design.  An optical ray trace from subject to target (sensor) must be utilized to determine which lenses are less problematic for this use.   The old lens splitters Francois referenced solved this problem by utilizing 2 lenses specially designed to accept the parallel ray bundle.  It's hard to fathom that the recent Canon patent discussed on this forum is the first advancement since those 1940's mirrored approach Francois referenced.  Canons designed solved all these optical issues, however, the aspect ratio issue might still exist, although I suspect they will flip the images with prisms to end up with two horizontal images vs. vertical. 

Outside of the future canon stereo splitter lens, the only other modern approach I have considered to this problem is using dual 2d camera lenses (interchangeable), which project on a fiber optic plate, then onto prisms which brings the dual imagery into the same aspect ratio of the sensor to prevent any pixel waste.   On the 2d camera, you photograph the fiber optic plate with a marco lens at proper magnification to assure the fiber optic plates contents ends up on the full sensor with close to zero waste.  While this is a very feasible but high tech solution, the cost of the fiber optic plates is extremely high...then add in optics, housing, prisms, design cost, etc., the product becomes ultra costly without high volume to amortize the costs.  Since Canon is more experienced with optical elements and prisms, their design is the best chance of a modern version of the 1940's 3d splitters.

BTW, a line diagram is not an optical ray trace.  So it will not determine the distortions which will occur by changing the mirror angles.  The 2d lens design is half the variable which is being left out of the equation. 

We do see how incredibly effective bringing two images from far apart to closely spaced can be, just pick up a decent pair of binoculars for proof.  Most of this technology is within reach of a company that specializes in imaging optics.  This is basically what Canon is intending to build, hopefully.  Just hoping if they do produce such, it does not have a major flaw, such as not flipping the images, and we end up with tall images vs. wide. 

Bill G



On Sat, Apr 10, 2021 at 1:18 PM Antonio F.G. via groups.io <afgalaz=yahoo.com@groups.io> wrote:
On Fri, Apr 9, 2021 at 03:09 PM, Depthcam wrote:
> By the way, such mirror design could produce parallel shots if the angle of the mirrors were adjusted for that.
Actually, no.  This will only work if a  mirror adapter is mounted on a set of two lenses  - as is the case with the Leiz Stemar or the Zeiss Stereotar C.  When you mount a mirror adapter on a single lens and keep the optical axes parallel, each side is viewing one side of the scene - just as if there were no adapter. In order for a left and right image to be recorded of the same scene, the optical axes MUST be converged.
I was not sure about this, but nothing like making a drawing of a "perfectly" parallel mirror adapter, with mirrors exactly at 45°:

The rays from a point at infinity arrive in parallel to the mirrors, and they send them to the lens in parallel as well. Therefore the lens prints a single point in the sensor. This is exactly the same as if the mirrors were not there.

It seems that the way to get two separate L&R images of the point is to deviate the mirrors somewhat away from 45°.
But I am still not sure whether this implies necessarily convergence of the two optical axis (may need another drawing:-)

Regards
     Antonio


Re: New 3D lens announced

JackDesBwa|3D
 

What I saw in the minimalist simulation was:
- when I move the source point toward the adapter, the two images of this point are going outward
- when I move the source point away from the adapter, the two images of this point are going inward (touching at the center at infinity)
- when I move the source point away left/right, the two images of this point are going left/right by the same amount each
- I had to add opaque planes to avoid most parasitic rays going directly from the source to the lens, but in my quick geometry some directions leak anyway
The general relative movements are correct for a regular 3D photo, but I was not able to figure out how the final image would look like.

JackDesBwa


Re: New 3D lens announced

Bob Aldridge
 

Yes. With a single lens the centre of each "bunch" of rays (left and right) MUST cross in the optical centre of the lens. If they don't they will be bent by the lens and destroy the image...

The unavoidable problem with this is - as has been stated - the bunches of rays Cannot be parallel.

Bob Aldridge

On 10/04/2021 21:18, Antonio F.G. via groups.io wrote:
On Fri, Apr 9, 2021 at 03:09 PM, Depthcam wrote:
> By the way, such mirror design could produce parallel shots if the angle of the mirrors were adjusted for that.
Actually, no.  This will only work if a  mirror adapter is mounted on a set of two lenses  - as is the case with the Leiz Stemar or the Zeiss Stereotar C.  When you mount a mirror adapter on a single lens and keep the optical axes parallel, each side is viewing one side of the scene - just as if there were no adapter. In order for a left and right image to be recorded of the same scene, the optical axes MUST be converged.
I was not sure about this, but nothing like making a drawing of a "perfectly" parallel mirror adapter, with mirrors exactly at 45°:

The rays from a point at infinity arrive in parallel to the mirrors, and they send them to the lens in parallel as well. Therefore the lens prints a single point in the sensor. This is exactly the same as if the mirrors were not there.

It seems that the way to get two separate L&R images of the point is to deviate the mirrors somewhat away from 45°.
But I am still not sure whether this implies necessarily convergence of the two optical axis (may need another drawing:-)

Regards
     Antonio


Re: New 3D lens announced

Antonio F.G.
 

On Fri, Apr 9, 2021 at 03:09 PM, Depthcam wrote:
> By the way, such mirror design could produce parallel shots if the angle of the mirrors were adjusted for that.
Actually, no.  This will only work if a  mirror adapter is mounted on a set of two lenses  - as is the case with the Leiz Stemar or the Zeiss Stereotar C.  When you mount a mirror adapter on a single lens and keep the optical axes parallel, each side is viewing one side of the scene - just as if there were no adapter. In order for a left and right image to be recorded of the same scene, the optical axes MUST be converged.
I was not sure about this, but nothing like making a drawing of a "perfectly" parallel mirror adapter, with mirrors exactly at 45°:

The rays from a point at infinity arrive in parallel to the mirrors, and they send them to the lens in parallel as well. Therefore the lens prints a single point in the sensor. This is exactly the same as if the mirrors were not there.

It seems that the way to get two separate L&R images of the point is to deviate the mirrors somewhat away from 45°.
But I am still not sure whether this implies necessarily convergence of the two optical axis (may need another drawing:-)

Regards
     Antonio


Re: New 3D lens announced

JackDesBwa|3D
 

Thanks for explaining how you can correct vertical disparities due to convergence of optical axes.

To complement the answer of Antonio, you might want to look at this montage explaining the principle visually (text complement in the description) with images taken with divergent optical axes (horizontal and vertical divergence) and rotation: https://stereopix.net/photo:koUNdrW2kF/

I guess SPM surely uses the same approach as StMani3

It is very likely, but then the feature matching (or the optimizer?) is not as good as the one you use in StMani3, because the keystone distortion is often noticeably sub-optimally corrected.

JackDesBwa


Re: New 3D lens announced

JackDesBwa|3D
 

I remain unconvinced that all photos taken with converging optical axes can be corrected.  The very simple reason for this is that if the convergence is at a subject at close range, the image recorded at far range may be completely different  due to the axes pointing at different parts of the scene that do not match.

In the situation you describe, I see the combination of two effects:
1) The keystone effect, due to the angle, which can be canceled out (with crop implications already mentioned)
2) The extremely excessive background disparity (going out of the image because the field of view is limited), due to the too large base, that cannot be corrected (at least not easily).
 
By the way, such mirror design could produce parallel shots if the angle of the mirrors were adjusted for that.
Actually, no.  This will only work if a  mirror adapter is mounted on a set of two lenses  - as is the case with the Leiz Stemar or the Zeiss Stereotar C.  When you mount a mirror adapter on a single lens and keep the optical axes parallel, each side is viewing one side of the scene - just as if there were no adapter. In order for a left and right image to be recorded of the same scene, the optical axes MUST be converged.

Could you detail how you come to this conclusion? I am not very good in optics (so my initial assumption might be wrong), but your version does not sound right to me.
I tried a quick and dirty simulation. It is very simplified, but it tends to confirm that the two situations are not equivalent. Maybe I missed something.
parallel_mirror_test.jpg

Also, I'd like to remind all that the subject of this thread is commercially available 3D lenses - not whether it is technically possible to correct distortions caused by poorly designed accessories.
My point is that if a product with inherent design flaws is put on the market, the buyers will mostly use them "as is" and that will result in images that cause eyestrain.

Sorry, but this sub-thread started because you suggested that stereo converters for single lenses shall be avoided because they introduce opposite keystone distortion with their design inherently bad which is a no-go. Several messages responded that well used, it could give interesting pictures.
Your arguments are not weak per se (people thinking or advertising that it gives good stereo without work is sad), but are weak in regard to the statement that the stereo converters for single lenses are inherently bad. I do not use them myself, but you would not convince me with this argument.

> You could also conclude that all lenses that exist are bad, because they introduce distortions
You seem to be missing the point that the cause of eyestrain in this particular case is OPPOSITE keystone distortion. It is the mismatch that causes the eyestrain - not the distortion itself.  If you take a picture of a building and point your camera up, you will also get keystone distortion but it will be the same in both the left and right images - therefore, comfortable to view.

I perfectly understand how these distortions behave. This particular line was to generalize your argument that using a device that has distortion to correct the distortion is very stupid, and show its weakness because we do it with lenses all the time. I thought about 2D photography, but actually the distortion of the lenses introduce mismatch and thus 3D discomfort as well.

JackDesBwa


Re: New 3D lens announced

Antonio F.G.
 

On Sat, Apr 10, 2021 at 04:41 AM, Olivier Cahen wrote:
Thanks for explaining how you can correct vertical disparities due to convergence of optical axes.
I wrote a paper to explain the alignment process used in the StMani3 program:
https://www.researchgate.net/publication/349634883_ALIGNMENT_OF_STEREO_DIGITAL_IMAGES

You can read just the first two pages that explain the approach: re-project the images of the unaligned stereo pair into a common virtual sensor plane. It explains there why any convergence angle can be corrected to null the vertical disparity, using just perspective transforms. You can skip the rest of the paper that tells the math process to find the virtual sensor plane.

Hey, only the vertical disparity can be corrected easily! The horizontal one is very other animal. I also talk about it in the document, and my best advise to correct a pair with the wrong horizontal disparity (either too much or too little), is to take your camera, go back to the place and shoot again taking care of the relationship between convergence, distance, stereo base, focal, et al:-)


For instance, it is not possible with StereoPhoto Maker.
I guess SPM surely uses the same approach as StMani3: Find the minimum error by successive approximations. (I do not know any other way). The approach requires to make an initial estimation of the solution, if the estimation is near the solution the process will quickly converge to the solution. If it is too far it will not converge, or converge a wrong solution.
SPM surely starts assuming the image pair is "reasonable", i.e. not excessive convergence or rotation. This may make it to fail if the initial convergence is too high. I guess it could perhaps be made to work by making an approximate manual alignment (the so-called "Easy Adjusment"), and a "Auto Alignment" afterwards (but I have not really tested this).

Have you tried Hugin? In spite it is not supposed to be made for stereo, JackDesBwa showed it is an extremely powerful aligning device, that includes at the same time stitching of several images into panoramas and lens correction (StMani3 does not deal with lenses nor panoramic's either). The biggest trouble is learning to use Hugin:-)

Regards
    Antonio


Re: New 3D lens announced

Olivier Cahen
 

Thanks for explaining how you can correct vertical disparities due to convergence of optical axes. For instance, it is not possible with StereoPhoto Maker.

Best regards, Olivier

Le 9 avr. 2021 à 22:56, Antonio F.G. via groups.io <afgalaz@...> a écrit :

On Fri, Apr 9, 2021 at 03:09 PM, Depthcam wrote:
 I remain unconvinced that all photos taken with converging optical axes can be corrected. 
What I say (and can prove) is that any optical convergence can be corrected to null the VERTICAL disparity.



The very simple reason for this is that if the convergence is at a subject at close range, the image recorded at far range may be completely different  due to the axes pointing at different parts of the scene that do not match.
You are talking now of HORIZONTAL disparity. Sure, if the horizontal disparity were much higher than the 1/30th rule, the pair would be un-viewable, regardless the vertical alignment. And this part can NOT be corrected, at least using simple perspective transforms. 



My point is that if a product with inherent design flaws is put on the market, the buyers will mostly use them "as is" and that will result in images that cause eyestrain.
I solemnly promise NEVER to put a mirror lens in the market:-)
But I would eagerly buy the Kúla Deeper if it were not discontinued. It is because I would like to give a stereo use to my Fuji X-M1 which is much much better camera than the NX1000's of my present rig.

Regards
     Antonio


Re: Standard Test Images Wanted #theory #viewing #vrheadset

Bill Costa as just a member
 

You're welcome to take anything from from here that may be of use.  ...BC


On Fri, Apr 9, 2021 at 7:52 PM Jay Kusnetz <jay31415@...> wrote:

I am volunteering to organize a resource for the community; a collection of stereoscopic images that could be used as standard test images. Basically our version of "Lena" or a "china doll" and a version similar to DSC's test film such as http://dsclabs.com/specialist-and-skin-tone-charts/
Would be good to also have a variety of subject matter, and especially textures that could show off the resolution of the hardware display, AND the processing pipeline.

Unfortunately, I don't have high end cameras, just a W3 and an old Nikon dslr, so I can't shoot anything high enough res and quality.

I can host them on the ggstereo.org site, and Internet Archive. Looking for suggestions for other repositories.

Initial use will be in an AltspaceVR world that will have the various measurements as part of the world (ie, 2 meter, 4 meter, and 6 meter floor marking in front of a 1 meter square picture)

Images should be either in the public domain, or https://creativecommons.org/licenses/ so that they can be freely used.
Please let me know if you have any images you can contribute.



--
Bill.Costa@...
+1.603.435.8526
https://mypages.unh.edu/wfc
No good deed goes unpunished.


Standard Test Images Wanted #theory #viewing #vrheadset

Jay Kusnetz
 

I am volunteering to organize a resource for the community; a collection of stereoscopic images that could be used as standard test images. Basically our version of "Lena" or a "china doll" and a version similar to DSC's test film such as http://dsclabs.com/specialist-and-skin-tone-charts/
Would be good to also have a variety of subject matter, and especially textures that could show off the resolution of the hardware display, AND the processing pipeline.

Unfortunately, I don't have high end cameras, just a W3 and an old Nikon dslr, so I can't shoot anything high enough res and quality.

I can host them on the ggstereo.org site, and Internet Archive. Looking for suggestions for other repositories.

Initial use will be in an AltspaceVR world that will have the various measurements as part of the world (ie, 2 meter, 4 meter, and 6 meter floor marking in front of a 1 meter square picture)

Images should be either in the public domain, or https://creativecommons.org/licenses/ so that they can be freely used.
Please let me know if you have any images you can contribute.


Re: New 3D lens announced

gl
 


I think it's really useful to highlight the issues with these types of adapters.  but it's also true that every stereo capture method (at least that most of us can afford) requires post processing of some kind to get the best from them.

What _is_ visually fool-proof at the consumer/prosumer level?  even 'easy to use' depth map images from phones are full of artifacts (just different ones), and each type of artifact compromises the viewing experience unless improved somehow.

what's interesting about stereo is how crucial those corrections are.  bad 2D photos may suck, but nobody would say that all 2D photography is bad just because there are badly shot or processed photos out there.  we can live with all kinds of 2D distortions.  but if you're gonna create stereo content, you're kinda forced to apply corrections unless you want to turn people off.

she's a harsh mistress ...
--
gl


On 09/04/2021 21:56, Antonio F.G. via groups.io wrote:
On Fri, Apr 9, 2021 at 03:09 PM, Depthcam wrote:
 I remain unconvinced that all photos taken with converging optical axes can be corrected. 
What I say (and can prove) is that any optical convergence can be corrected to null the VERTICAL disparity.



The very simple reason for this is that if the convergence is at a subject at close range, the image recorded at far range may be completely different  due to the axes pointing at different parts of the scene that do not match.
You are talking now of HORIZONTAL disparity. Sure, if the horizontal disparity were much higher than the 1/30th rule, the pair would be un-viewable, regardless the vertical alignment. And this part can NOT be corrected, at least using simple perspective transforms. 



My point is that if a product with inherent design flaws is put on the market, the buyers will mostly use them "as is" and that will result in images that cause eyestrain.
I solemnly promise NEVER to put a mirror lens in the market:-)
But I would eagerly buy the Kúla Deeper if it were not discontinued. It is because I would like to give a stereo use to my Fuji X-M1 which is much much better camera than the NX1000's of my present rig.

Regards
     Antonio

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