Rift custom lens cups experiment

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Rift custom lens cups experiment

Post by geekmaster »

Synopsis: DIY Rift 2-inch 5x aspheric acrylic lenses in offset position give near perfect FoV in Rift, but need custom pre-warp.

Because the longest (A) eyecups give me the largest FoV, I am using them even though they are out of focus. I tried the other eyecups, but only the shortest (C) eyecups gave me a sharp focus at the expense of a much smaller FoV (like looking through binoculars. I wanted to try swapping lenses between the A and C eyecups, but my snap-in lens retainer rings are GLUED in place. Too bad, and not what I expected...

So I decided to try my DIY Rift 2-inch 5x aspheric acrylic lenses (as recommended by PalmerTech in the DIY Rift thread).

I cut a strip of cardboard from a cereal box, the width of the front panel of the box. This was enough to wrap around my lens (while it is mounted in its lens holder ring), with a little extra overlap. I put masking tape along one long edge, covering about 1/3 of the cardboard. I stretched and pulled the cardboard strip over the sharp edge of a table to curl it, then I wrapped it around my lens (bulged side inward) with cardboard covering about the bottom 1/3 of the lens holder ring and tape extending above the lens. After pressing the tape firmly into the grooves on the lens ring, I trimmed the excess with a wire cutter (scissors did not work well for that). Then I taped down the overlapped side of the cardboard, forming a tube. I trimmed the tube height so that the entire height including the lens was about one inch.
custom-eyecup.jpg
With one eyecup removed from my Rift, I placed this DIY eyecup over the hole. When centered, it fits well between the three raised eyecup retainer clips.

When viewing through the centers of the 2-inch lenses, the screen is in good focus for me (near-sighted) but I can see too much of the internal separator that blocks you from seeing the wrong image. I shifted the eyecup outward so the outer two eyecup clips were pressing into the outside my improvised lens cup (deforming it a bit), which made me look through the inner offset of the lenses. This gave me a PERFECT FoV, where EVERYTHING was visible. I could see a little beyond the outer pixels in all directions, but ONLY when looking straight forward. When rotating my eyes toward any edge, all I can see is pixels.
rift-customcup.jpg
The problem with offset viewing like this is that the inner part of the image looks horizontally stretched, and the outer part of the image looks horizontally compressed. This is exactly as expected when using offset lenses, and it is the SAME thing that will be experienced by somebody with a smaller IPD than the Rift uses.

To compensate for the offset lens nonlinearity, a new pre-warp shader will need to be created, and each eye will need to use a MIRROR of the shader, which compresses the inner edges a little from what they use now, and expands the outer edges a bit more than they do now. Unless corrected in pre-warp, this asymmetric offset nonlinearity will pull the inner and outer edges of the image inward making it look like it is curving toward the viewer, and can cause a small amount of vertical misalignment at the edges (where the Rift non-overlap makes it a non-issue).

I would MUCH PREFER to use my 2-inch 5x lenses in my Rift, but only after I have an asymmetric pre-warp filter that works correctly with them.

When used as offset lenses, there is a bit of a gap on the inside of the rift eyecup opening. To prevent dust entry, I need to modify my DIY eyecups to cover that gap. And I need to add tabs so my eyecups can snap into the Rift eyecup retainer clips.
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Re: Rift custom lens cups experiment

Post by geekmaster »

(bump) .. for the 52 people who already read the first post, I added photos and more details...

EDIT: Because different people may need these lenses mounted at different heights, and because my eyecup is cylindrical, I was planning to make an inner and outer cylinder so that the lenses can telescope in and out to adjust their focus. I did the above experiment first, and then posted this. I may make a telescoping adjustable-focus eyecup later, after I get a working asymmetric pre-warp filter.
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Re: Rift custom lens cups experiment

Post by Captaincook »

What is the difference between spheric and aspheric lenses in case of Rift? And how to calculate these 3x 4x 5x? By the shape of the lens?
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Re: Rift custom lens cups experiment

Post by Pingles »

Eyepieces might be an interesting market.
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Re: Rift custom lens cups experiment

Post by geekmaster »

Captaincook wrote:What is the difference between spheric and aspheric lenses in case of Rift? And how to calculate these 3x 4x 5x? By the shape of the lens?
Spheric lenses have more spheric (and other) aberration. That can be corrected somewhat by software, but better to use aspheric lenses. The 5x lenses work perfectly for me, but I am near-sighted (myopic). They let me see all the pixels up to the top/bottom/lef/rift edges, and when looking forward (where the eye pupil is positioned more forward) I can see a little of the left and right borders, but not when looking directly at them. IMHO that is as good as it gets.

EDIT: To answer your second question about lens calculation, here are some lens equations:
http://www.mystd.de/album/calculator/lens_equation.html
And some lens magnification formulas:
http://www.mystd.de/album/calculator/magnification.html
And an online lens calculator:
http://www.mystd.de/album/calculator/


EDIT2: Ordinary aspheric lenses correct for spherical (and other) aberrations, but not chromatic aberration. Only hybrid aspheric lenses also correct for chromatic aberration. See this for more information:
http://www.mtbs3d.com/phpBB/viewtopic.p ... 76#p134076
Last edited by geekmaster on Sun Jun 23, 2013 5:22 pm, edited 2 times in total.
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Re: Rift custom lens cups experiment

Post by nateight »

Wow, great experiment! I've been saying all along I want to see dozens of different lens and eyecup options for sale in the Oculus Store ASAP. Surely these things can't be so expensive to produce that Oculus couldn't turn a modest profit while selling an inexpensive, ideal set of optics to every single Rift owner? The only problem would be knowing exactly which set is right for you, and there might be a solution to that as well - charge slightly more than cost for a full kit of all available lenses and market it to VR arcade owners and ophthalmologists. I've been with my eye guy since I was a grade-schooler and I'd drop him in a heartbeat, drive 200 miles, and pay a typical office visit fee just to have a professional nail down exactly what I'd want to buy. ;)
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Re: Rift custom lens cups experiment

Post by geekmaster »

I have plans for a custom eyecup with adjustable IPD (the lens barrels slide left/right, and telescoping tubular lens cups that slide in and out to adjust focus. I also plan to design a flexible pre-warp filter to handle asymmetrical pre-warp, so that lens offset can be used to center the FoV on the onscreen images to avoid seeing borders, and also to allow extended horizontal FoV when using fresnel lens stacks in these custom eyecups for the Rift.

To be more sturdy (no breakable tabs), I replaced the eyecup retainer tabs with a flat disc, which has notches cut into it that fit over the eyecup retainer clips and rotate under them. This disc has four parallel clips (two top and two bottom) to allow a second eyecup base to slide under those tabs, and to which the telescoping lens barrels are mounted.

My "universal" eyecup design will use the larger 2-inch lenses for maximum viewable onscreen pixels, or can use fresnel lens stacks for maximum horizontal FoV. My eyecup will telescope in and out for focus adjustment, and will slide side-to-side for IPD adjustment. They will have matching software to compensate for all these adjustments.
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Re: Rift custom lens cups experiment

Post by 3dvison »

Hi geekmaster,
I thought the Dev. Kit Rift was using a lens that would have atleast the same diameter as the 5x Diy lens. But looking at your second picture, it looks like the Dev. Kit lens has a much smaller diameter than the Diy 5x lens, is that true or an optical illusion in the picture ?
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Re: Rift custom lens cups experiment

Post by TheHolyChicken »

I love that you've had your Rift for about a day and you're already sawing bits off.
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Re: Rift custom lens cups experiment

Post by zalo »

Hopefully nthusim will let you adjust your warp parameters so you can experience your adjusted optics with a wide variety of games.

It might be in usability's best interests to have small linear potentiometers inside the consumer Rift measuring the configurations of the lenses, and having implemented software automatically adjust the warp to compensate.

This way, a formula could handle warp and chromatic aberration automatically and dynamically in real time, so the user can quickly find the best viewing experience.
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Re: Rift custom lens cups experiment

Post by geekmaster »

TheHolyChicken wrote:I love that you've had your Rift for about a day and you're already sawing bits off.
Usually I buy two of EVERYTHING just so that I can mod one and have another one to use when I break it, (and for side-by-side signal comparisons with my 'scope when needed). Unfortunately, I only have ONE Rift, so in this case nothing is modified. Just one prototype DIY replacement lens cup, with more designs in the idea pipeline...

But yeah, one of the primary product specifications that strongly influences my purchasing decisions is "hackability" ( for almost EVERYTHING that I buy). More "open" is more "better". :lol:
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Re: Rift custom lens cups experiment

Post by geekmaster »

3dvison wrote:Hi geekmaster,
I thought the Dev. Kit Rift was using a lens that would have atleast the same diameter as the 5x Diy lens. But looking at your second picture, it looks like the Dev. Kit lens has a much smaller diameter than the Diy 5x lens, is that true or an optical illusion in the picture ?
The lens eyecups are truncated cones with a BASE that is about 2-inches in diameter, which is why my two-inch 5x lenses use eyecup TUBES.
lens_dia.jpg
As you can see in the photo, the lens is laying on one of my fresnel page magnifiers that has a built-in ruler. Using the inches scale, you can see that the visible portion of the Rift lens is about 1.5-inches in visible diameter. That is 25% smaller diameter (or 56% of the surface area) of the two-inch lenses. Realistically, the diameter is not as important as the image quality, and the Rift lenses are plenty good enough if they work for your eye prescription. Smaller lenses not only cost less, but they also weigh less, and both are important concerns in a product design such as the Rift.

The only reason I began this experiment is because none of the lenses supplied with the Rift work well for me (unless I go get some contact lenses), and these 2-inch lenses are what I already had to work with from previous experiments.
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Re: Rift custom lens cups experiment

Post by Randomoneh »

I have plans for a custom eyecup with adjustable IPD (the lens barrels slide left/right,
You are awesome.
That (along with the software ISD and camera spacing adjustment) would be the ideal solution.
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Re: Rift custom lens cups experiment

Post by Diorama »

Awesome stuff. Really glad someone is doing this stuff, and glad it's you, geekmaster ;)
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Re: Rift custom lens cups experiment

Post by KBK »

geekmaster wrote:
TheHolyChicken wrote:I love that you've had your Rift for about a day and you're already sawing bits off.
Usually I buy two of EVERYTHING just so that I can mod one and have another one to use when I break it, (and for side-by-side signal comparisons with my 'scope when needed). Unfortunately, I only have ONE Rift, so in this case nothing is modified. Just one prototype DIY replacement lens cup, with more designs in the idea pipeline...

But yeah, one of the primary product specifications that strongly influences my purchasing decisions is "hackability" ( for almost EVERYTHING that I buy). More "open" is more "better". :lol:
Yes, I tend to buy two myself. one is a 'control', the other is for modding, then the two can be compared. Always prudent to have a control.
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Re: Rift custom lens cups experiment

Post by 3dvison »

Thank you geekmaster for the reply.
I used the 2" 5x lenses with my Diy Rift also, but I also made lenses out of the 3inch UltraOptix Magnifier. Yes more weight is not good for an HMD(and I needed two per lens), but the bigger diameter lens does make a nice difference. In fact, anyone who used both sets of my lenses, liked the 3inchers much more than the 2inch lenses hands down.

http://www.amazon.com/UltraOptix-Round- ... _sim_hpc_8
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Re: Rift custom lens cups experiment

Post by nnamd »

Image
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Re: Rift custom lens cups experiment

Post by geekmaster »

nnamd wrote:Image
With a pair of those, who needs a Rift? :lol:
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Re: Rift custom lens cups experiment

Post by Dnhkng »

It should be reasonably straightforward to make custom cups for prescription and IPD with a 3D printer. Once my Rift arrives, I plan to start experimenting with such cups, with the 3D structure generated parametrically from diopter and IPD. Would anyone be interested in such custom made eyecups?
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Re: Rift custom lens cups experiment

Post by MSat »

Something I found to be a bit curious was that in USC's Rift lens cup mods, they recommend 7x aspherics instead of 5x. I now assume it was to avoid seeing the divider as you have.
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Re: Rift custom lens cups experiment

Post by squibbfire »

Pingles wrote:Eyepieces might be an interesting market.

It might be like the telescope market...high fov 2inch lenses improve viewing a lot sometimes!.

Maybe the lenses could be changed to improve viewing and immersion!
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Re: Rift custom lens cups experiment

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MSat wrote:Something I found to be a bit curious was that in USC's Rift lens cup mods, they recommend 7x aspherics instead of 5x. I now assume it was to avoid seeing the divider as you have.
There are THREE ways to not see the divider:

1) You could use the 2-inch 5x aspheric and place the optical center outward, so you are viewing through the inner half. That shifts the image inward so you do not see the divider (or only a little out of the corner of your eye when looking straight forward). It also centers the available pixels so you might see a little of the outer border when looking forward.

2) You could use the 7x lenses recommended by USC. That would magnifiy the pixels so they fill a larger viewing area, pushing the borders outward in all directions. That makes many more pixels UNUSED, and amplifies the screendoor effect.

3) You could partially block the user's viewpoint by masking off part of the lenses. That is what you can see in John Carmack's prototype he demos in the early days of the kickstarter (a little tape on the inner side of the lens). The current Rift model added a vertical divider between the screen halves, so even if your view could have seen the other half of the screen, the divider prevents that. Also, the current Rift uses 1.5-inch lenses instead of 2-inch lenses, which is equivalent to masking off the outer 1/4-inch of the 2-inch lens all around its circumference.

The downside of using smaller lenses (as the current Rift lens cups use) is that besides blocking the inner border like some prototypes did, it also blocks the VERTICAL dimension where there are actual useful (but hidden) pixels. The Tuscany demos display pixels there, but you can only see them if you position your Rift so you see more top and less bottom, or more bottom and less top. In the Valve demos they blacked out these vertical pixels that are blocked by the border around the smaller lenses.

You can use larger offset lenses like I posted earlier, but that requires asymmetrical pre-warp.

Perhaps the ideal lens would be to take a 2-inch lens and grind enough off the inner (and optionally outer) edges so your nose is not in the way while trying to view through its optical center, and so it cannot view the 640-pixel wide horizontal borders. The extra half-inch of vertical lens dimension would let you see the full 800-pixel high screen. This cut-down 2-inch lens would also support existing symmetrical pre-warp.
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Re: Rift custom lens cups experiment

Post by nvman90 »

Haha I did exactly the same thing, before seeing this post.

I used little tabs that I cut from some packing material, and placed them such that I can still lock the lenses into the slots.

I find these lenses to be much better. I get a resolution similar to the A cup (how much of the screen is being captured through the lense) without having to wear glasses. Second, these lenses are clearer than the ones provided with the rift. The rift lenses are clear on axis, but once you get off-axis they clarity drops much faster than these lenses.

However these lenses have a higher dispersion. However, this is actually normal for me, since the glasses I wear have similar color dispersion.

Ya the pre-warping isn't quite right for these lenses, but that's barely noticeable.
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Re: Rift custom lens cups experiment

Post by geekmaster »

nvman90 wrote:Haha I did exactly the same thing, before seeing this post.
"Great" minds think alike! :lol:
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Re: Rift custom lens cups experiment

Post by EdZ »

Just remember: when the lens separation no longer = IPD, then you lose the 'more pixels in the centre-forward area' effect, and encounter new distortion issues. With the current lens setup, you get the highest resolution (i.e. pixels subtend the smallest angle) when you look forward. With a shifted-lens setup - especially one where the lenses are shifted outwards - your 'relaxed' view will be through the more distorted edge section of the lens, and only one eye will be able to look through the highest effective resolution region (lens centre) at a time (i.e. each eye will see pixels that subtend a different angle!).
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Re: Rift custom lens cups experiment

Post by geekmaster »

EdZ wrote:Just remember: when the lens separation no longer = IPD, then you lose the 'more pixels in the centre-forward area' effect, and encounter new distortion issues. With the current lens setup, you get the highest resolution (i.e. pixels subtend the smallest angle) when you look forward. With a shifted-lens setup - especially one where the lenses are shifted outwards - your 'relaxed' view will be through the more distorted edge section of the lens, and only one eye will be able to look through the highest effective resolution region (lens centre) at a time (i.e. each eye will see pixels that subtend a different angle!).
It only takes a little offset to pull the image inward enough to center it so you (almost) see the inner and outer borders. When looking through lens centers, you clearly see the center divider with 2-inch lenses, and your nose in in the way to get them close to your eyes without cutting away part of the lens (or at least removing the black rings around them, if your nose is narrow enough for that). The distortion while looking forward is virtually undetectable with such small offset as I tested, while at the same time almost no pixels are wasted. Most of the distortion is near the edges, but an asymmetrical pre-warp will be needed to allow stereoscopic convergence when one eye is looking over the nose the nose, or there will be some vertical misalignment making that difficult. But looking forward looks great even with incorrect pre-warp distortion compensation.

It is very nice that the Rift has large enough eye holes to accomodate 2-inch lenses. Perhaps it was specifically designed that way. If not, that is a very serendipitous coincidence.
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Re: Rift custom lens cups experiment

Post by pizzy00 »

I will be buying lens soon to try this mod out on my Rift.

It would be cool if Oculus would sell different lens in their online store.

Hopefully Palmer reads this.
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Re: Rift custom lens cups experiment

Post by geekmaster »

I only recommend these lenses for people who are too near-sighted to use the standard lenses shipped with the Rift Dev Kits. For me, these larger lenses seem to work much better.

Also, since I started wearing my head strap a lot tighter, I get more field of view from the standard A lenses. Compressing the foam tightly against my face gets the lenses closer to my eyes.

So the tip is, if your FoV is not large enough, tighten the head straps...

To get your eyes closer to the lenses, it might also work to remove the foam and wear the rubber directly against the skin, like a diving mask.
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Re: Rift custom lens cups experiment

Post by geekmaster »

at http://www.mtbs3d.com/phpBB/viewtopic.php?f=140&t=17070, zalo wrote:So for those of you who already have Rifts, I think you're starting to realize that there is a lot that can be done by messing around with the eyecups.

Image

After reading about foisi's fresnel triumphs, I thought I'd try out the fresnel route. I made the USC eyecup and glued two of these fresnel lenses together and got optics that are very close to the Rift's eye cups. Make sure to print the cup without a raft, otherwise it will be really difficult to slide into the Rift assembly.

Differences compared to the vanilla Eyecups:
  • Brought a lot more pixels into the FoV
  • Significantly lessened the screen-door effect :woot
  • Made the image slightly cloudier (but it's uniform so it's okay)
  • Surprisingly well focused
  • Warps the image a lot more around the far edges.
I'm really happy with how much more fidelity I can get out of the screen with a new eyecup that only costs me ~$5 in raw materials. It also makes me think that there is a whole world of upgrades that can be made to the rift with just the addition of a few eyecups. The extra Screen FoV is really impressive. I can see all the borders in TF2, so I'll have to recalibrate it for that. I'm printing out another eyecup as I type this post, so I can get the full experience. ;)

I hope more people try making custom lenses! It's exciting!
I tried fresnel lenses, but I mounted them directly over the eyecup clips (in place of eyecups), so they get a wider FoV by looking directly through the larger 2-inch holes. I used offset fresnel lens stacks, as described in my "fresnel lens stack" thread, and it worked quite well with my eyes as close to the lenses as possible, but requires a custom pre-warp to prevent VR objects from looking about 50-percent too wide (i.e. about 50% wider horizontal FoV than standard Rift lenses).
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Re: Rift custom lens cups experiment

Post by pizzy00 »

Just bought the lens after read your post. I do not have a 3D printer.

If anyone finds an alternative to 3D printed eyecup please post.
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Re: Rift custom lens cups experiment

Post by zalo »

pizzy00 wrote:Just bought the lens after read your post. I do not have a 3D printer.

If anyone finds an alternative to 3D printed eyecup please post.
Cut out some cardboard from a cereal box, you peasant! :lol:

But geekmaster is right; you can get more FoV if you have a straight up cylindrical lens holder. You get to use more fresnel lens if the cup doesn't taper off toward the end! The slant on one side of the USC cup is to allow room for your nose. The optics on the fresnel lenses are very forgiving, so even if you get the two optical centers between the lenses misaligned (like I did on my first lens! :( ) you can still get a usable eyecup. I just 3D printed it because a) I had a printer on hand b) I want to slip them in and out easily.

Luckily, thanks to the TF2 "vr_calibration" command (allowing for custom warp settings), I probably won't have to take my lenses out until a new uncalibratable game comes along. ;)

EDIT: I just noticed you said "lens". I hope you bought at least six. It takes two to make an eyecup, and you'll want a practice pair.
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Re: Rift custom lens cups experiment

Post by pizzy00 »

zalo wrote:
pizzy00 wrote:Just bought the lens after read your post. I do not have a 3D printer.

If anyone finds an alternative to 3D printed eyecup please post.
Cut out some cardboard from a cereal box, you peasant! :lol:

But geekmaster is right; you can get more FoV if you have a straight up cylindrical lens holder. You get to use more fresnel lens if the cup doesn't taper off toward the end! The slant on one side of the USC cup is to allow room for your nose. The optics on the fresnel lenses are very forgiving, so even if you get the two optical centers between the lenses misaligned (like I did on my first lens! :( ) you can still get a usable eyecup. I just 3D printed it because a) I had a printer on hand b) I want to slip them in and out easily.

Luckily, thanks to the TF2 "vr_calibration" command (allowing for custom warp settings), I probably won't have to take my lenses out until a new uncalibratable game comes along. ;)

EDIT: I just noticed you said "lens". I hope you bought at least six. It takes two to make an eyecup, and you'll want a practice pair.
Thanks for info. I bought 9 there was a minimum of $10 order needed.
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Re: Rift custom lens cups experiment

Post by geekmaster »

zalo wrote:... The optics on the fresnel lenses are very forgiving, so even if you get the two optical centers between the lenses misaligned (like I did on my first lens! :( ) you can still get a usable eyecup. I just 3D printed it because a) I had a printer on hand b) I want to slip them in and out easily. ...
Lens misalignment will make the pre-warp more difficult, but not impossible. Viewing lenses through an offset position (not through their optical centers) causes asymmetrical distortion (more stretching on one side). This causes some stereoscopic misalignment, which can be compensated in software using an ASYMMETRICAL (non-symmetrical) pre-warp filter. So far, all documented filters for Rift pre-warp have been for symmetrical lens positions, but I and others (including Oculus) have plans for asymmetrical pre-warp in the future.

For now, with existing pre-warp filters, it is best to avoid using offset lens positions. But with offset eyecups, you can cut an offset lens that moves the optical center back to where your IPD needs it for symmetrical pre-warp.

In my case, I moved my 2-inch cylindrical eyecups outward to an asymmetrical position for best viewable use of the Rift display (intentional offset). But I really need asymmetrical pre-warp with that, as I mentioned in a previous post. Nose-relief was not really an issue for me with those 2-inch cylinders (1-inch tall, including the lens).
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Re: Rift custom lens cups experiment

Post by zalo »

Small Update:
photo111.JPG
I printed out a third cup (since the one from the first photo was kind of messed up), and assembled a second cup.

I like using these lenses over the original ones because TF2 looks a lot sharper with these. I still can't read the text because the HUD doesn't recalibrate with vr_calibration, but the rest of the game looks good. Also, the straight edges on the cup allows more room for bigs noses, I guess. I might mess with the model so the opening in the cups are bigger to let more fresnel show.

EDIT: Btw in my earlier post, I was talking about the two fresnels in the stack (on one eyecup) being misaligned. Surprisingly, it didn't impact the image significantly, but I have since aligned them. That's interesting though about offset lenses. I wonder what Oculus has up its sleeve.
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Re: Rift custom lens cups experiment

Post by geekmaster »

zalo wrote:EDIT: Btw in my earlier post, I was talking about the two fresnels in the stack (on one eyecup) being misaligned. Surprisingly, it didn't impact the image significantly, but I have since aligned them. That's interesting though about offset lenses. I wonder what Oculus has up its sleeve.
Besides making pre-warp more difficult, offset lenses shift the image so that less of the center divider is visible, and more of the outer pixels are visible. One good thing from that is more stereoscopic overlap. You can get more chromatic aberration though, requiring separate pre-warp distortion for each color plane (but it does not seem bad enough to bother with in many cases).

Using extreme offset lenses, stacked for both left and right stretching, gives a much wider horizontal FoV (landscape mode, matching your actual eye FoV) than the rift uses (portrait mode, unlike your actual eye FoV). They require a complex pre-warp algorithm though, which I have not implemented yet.

I am experimenting with variations of simple "approximate" pre-warp algorithms that will work on small devices like the Raspberry Pi, where any incorrect distortion is hopefully in the outer extremes where not visible, or at least not distracting. Computer graphics has a long history with approximate solutions (and still does)...
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Re: Rift custom lens cups experiment

Post by msfreemind »

pizzy00 wrote:Just bought the lens after read your post. I do not have a 3D printer.

If anyone finds an alternative to 3D printed eyecup please post.
Is there a local 3D printing service that you can use?
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Re: Rift custom lens cups experiment

Post by Plagued »

Hi, could anyone provide me with some measurements, I want to make some custom lenses for my son, my rift should be turning up some time soon but I'd like to be getting on with things in the mean time.
A) lens hole diameter
b) the bezel thickness around the lens hole
c) the distance between the lens holes
I can mock something up to build the lenses on. I'm hoping to make the lens assembly adjustable so this is just so I can make a mount for the lenses.
Cheers
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Re: Rift custom lens cups experiment

Post by zalo »

I don't have my rift on me to measure at the moment, but the USC Eyecup fits just fine. If you have a cad program, I think you can measure the dimensions of the model.
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Re: Rift custom lens cups experiment

Post by remosito »

geekmaster wrote:
I am experimenting with variations of simple "approximate" pre-warp algorithms that will work on small devices like the Raspberry Pi, where any incorrect distortion is hopefully in the outer extremes where not visible, or at least not distracting. Computer graphics has a long history with approximate solutions (and still does)...
After reading the fresnel stack thread I have been wondering about that custom pre-warp.

Couldn't one use an interactive pre-warp design application:

Where you display a series of increasingly dense grids. Lets say start with 2-3 grid points in each axis. Then each iteration you add another 1-3 per axis.
The perfect onscreen grid will look all wonky after it passes through your lenses and be all warped.

For each iteration you make each intersection point selectable and moveable. Then the user can move the grid points until he sees a perfect grid with his eyes. The offset correction of the gridpoints would be the pre-warp. Or am I overlooking something?

The more iteration the user works himself through the more accurate the resulting pre-warp. One could as well start instead of a virgin grid by providing a number of pre-warps the user can choose the one that looks best. And iteration x+1 new gridpoints could be estimated/predicted by using prewrap offsets from iterations 1 through x. Maybe even different predictions based on different models the user quickly rotates through for the one being best.

All cutting down a lot on required user work.
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Re: Rift custom lens cups experiment

Post by msfreemind »

I don't think customizing an eyecup for IPD makes sense anymore, since the latest release of the SDK removed IPD from the distortion projection. IOW, the distance between the projection centers is fixed at 64mm.

You could probably create your own demo where the distortion is handled differently (or you can find games/demos that use an older SDK version), but anything that uses the new SDK distortion handling will be assuming 64mm lens separation.
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