Parralex Inversion Fix???

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iondrive
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Re: Parralex Inversion Fix???

Post by iondrive »

Hi N,

Things are not looking good:
Well I thought that last trick would do something good but too bad I only tested it on my CRT because when I tested on my DLP, I could see that the PJ compensates for that adjustment so it doesn't have the desired effect. Yes, you did it right and it would have been a good trick if it had worked but the technology is just not the same as a CRT. It looks like it memorizes the image and displays it at the next vertical sync pulse and so that cancels out any fine tuning of the timing of the image between pulses. At this point, I could recommend some other things but the situation doesn't look good right now. I'm starting to think your PJ has an unresolvable(?) color mismatch issue and I would like you to test that in a weird way but first some things that probably won't work.

Use one of Windows' "Restore Points" to restore things back to before you had this problem. That would be some time before March 5th.

Use the Reset function under your projector's help menu.

Change video timing standard - choices are General, Discrete Monitor, Coordinated Video, or Fixed Aspect Ratio Timing (FART). I tried these on my DLP with no effect as expected. Don't bother with this.

Change video signal timing manually - it turns out that changing vertical backporch and frontporch do something similar to what you just tried by moving the image down but it can also squash or stretch the image. This shouldn't help. Don't bother with this. Now for some "fun"...


The spinning-pen test:

( I'll put this in it's own thread later but right now I'll just give you a brief version here. )

This may seem weird but please try it. It will help you and me figure out exactly what is going on with your PJ's colorwheel and it's a technique that you can use with any future DLP PJ or TV you may get.

Step 1. Get a white pen with a clip on it and tie it to about 8 inches of string or rubberbands.
Step 2. set up your eDim dongle and eDim glasses for use with your setup (original TH2Go setup is fine)
Step 3. Start up your PJ and switch to 60 Hz Presentation mode
Step 4. Make the screen all white with a maximized empty text window or bitmap.
Step 5. get edim glasses shuttering with Activator but don't put them on yet.

Step 6. twirl the pen in a circle in the beam of the projector. Don't look at the screen through the twirling pen because it's harder to see the colors that way. See the colors better by offset viewing against a dark background. Now you see the colors of your colorwheel. It should look something like this:
spinning-pen-no-shutter.GIF
Notice that it's made up of continuous bands of colors probably in this order: red, green, white, blue (RGWB), but how can you tell that red is the first color of a frame? That's next.

Step 7. Repeat step 6 with the glasses on and one eye closed. You will see dark segments where colors are missing. Try to adjust the twirling speed to steady the image but I know it's hard. You should see 12 colors between the dark regions because your PJ has a 4-color wheel and it's speed is 3x so that it spins three times for each frame. Instead of counting 12 colors, just note the first and last colors (expect red first, then blue last) and count 3 blue bands in each sweep of colors. Just to be clear, I expect this pattern: darkness,RGWB,RGWB,RGWB,darkness with a possible thin red band on the end since that's what I see with my old PJ. The purpose of step seven is to get you familiar with the PJ's "normal" colorwheel operation. That's why you're at 60 Hz and you're in Presentation mode because it shows the white band better. For brighter viewing, look and twirl in a direction perpendicular to the beam while standing closer to the PJ. Now you see the standard colorwheel operation. I suspect a different behavior at higher freqs so let's test it. First here's an image of how it would look if your colorwheel only spun once per frame. My old PJ shows 8 colored bands between the dark regions instead of 4, and that proves that it spins twice per frame (if it has 4 colors per cycle). Yours is different.

A shuttered view of a hypothetical 1-color-cycle per frame projector using a 4 segment color wheel (RGWB). Light from every second frame gets blocked creating the dark zones. Now you know that the red band comes first in the color cycle assuming you spin the pen clockwise.
spinning-pen-shuttered.GIF
Step 8. de-Activate glasses, change freq to 75 Hz, Activate glasses, repeat step 7. Notice differences between each eye-view. I expect the two views to have different patterns. Try to note the first and last color for each view. From this info, we can tell exactly what the PJs are doing and where the red ghost is coming from. It just takes some analysis.

This all may seem tedious and complicated but I think it's fun so try and have it be fun for you too. I bet you never expected this when I started to "help" you.

awaiting your results,

--- iondrive ---

PS: if you do alot of twirling, rubberbands may be softer on your skin so you don't get a raw patch. I guess you could use yarn or gloves. jeez.
And don't let the pen fly off into someone's eye.
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Last edited by iondrive on Sun Mar 25, 2012 9:50 pm, edited 4 times in total.
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Re: Parralex Inversion Fix???

Post by The_Nephilim »

well i have a problem with the inverter setup. I can NOT get the glasses to come on with the inverter plugged into the nvidia emitter?? I tried the ed activator is does not activate the glasses like before??

I am NOT sure what happened but it is not working anymore.. back to square one again..
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Re: Parralex Inversion Fix???

Post by iondrive »

hmm, alright. Remember sliding the screen down with nvidia's control panel? Slide it back up some or if that doesn't work, then select a different timing mode on the next tab of that window. It shouldn't matter which mode you choose as long as it's different from the current one. Try Discrete Monitor or Fixed Aspect timing modes. I think I may have experienced something similar to this when I was goofing around with my settings.

What are we doing now?
We are trying to determine how your colorwheel behaves at non-60 Hz freqs. My old PJ's colorwheel goes through 2 cycles per frame at 60 Hz, but it goes through 1 1/2 cycles at other freqs. I've been able to reproduce your disappearing red ghost on my old PJ using some old Simuleyes glasses and it's a result of that uneven color-cycle. When looking at a white screen at 85 Hz through shutter glasses, I see 6 colors/frame instead of 8: RGWBRG with one eye and WBRGWB with the other eye. No time delay will balance the colors with IR glasses but wired glasses have a chance if I shorten the clear time on each lens. Then I could cut off the first and last colors so that RGWBRG becomes GWBR, and then WBRGWB becomes BRGW but I think that's too much trouble so I use my other "3d-ready" projector instead. Another reason for not using that idea is because it would darken the screen more and I didn't want that. The question for your PJ is: at 75 Hz, does the colorwheel go through 3 cycles, 2 cycles, or something in-between? If it's in-between, then I think we can give up.

Testing without glasses:
You can use sView without glasses. Open this black and white test image in fullscreen using sView in crosseyed input mode (the default).
BW-RL-test.PNG
You can spin the pen while this is showing and it's like you're looking through a shutterglass even though you're not. This is an excellent reference view since you know there's no shutterglass timing delay since you're not using shutterglasses at all. You can compare this view with the view of the pure white screen viewed through one glass. Differences will be from time delay or light leakage through the dark phase of the glasses. This is how you tell what's going on but don't have a seizure from that black and white image flickering.

After you do this without the glasses, you can use the nvidia glasses with sView and you should be able to see some extra red through one of the lenses. That's your ghost. If you need/want, you can make a pure white version of the image above and use that. Once you know this technique, you can come up with many variations of your own. Then you can answer your own questions about color timing issues.

Tell me if you understand all this from this post and my previous one and say if you think it's a waste of time or fun/interesting. Personally, I think it's awesome to be able to do such precise timing tests with a pen and some string.

--- iondrive ---
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Re: Parralex Inversion Fix???

Post by The_Nephilim »

ok I think I got it now..

1st test.. RGWB 60hz Presentation mode.. white backround Text Document opened
2nd test RB with red sliver after the Blue.. Glasses on, Right Eye shut 75hz Same with other eye..EDITED!!!!!
3rd test.. RB with red sliver after the Blue.. w/Black and White image NO glasses in Sview 75hz..

I do NOT understand the color Cycles?? can you explain again??



Well I guess with that red band in the last test there is NOTHING I can do about the Ghosting Correct?? OR what do all these tests mean and what can be done??

EDIT: While I do NOT fully understand what this is telling me I thought it was cool and did NOT know this was possible to see the color wheel like this..
But from what I am seeing I have a color mismatch and there will be nothing I can do about the ghosting.. just wierd I never noticed it as much before???
Last edited by The_Nephilim on Tue Mar 27, 2012 11:09 am, edited 1 time in total.
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Re: Parralex Inversion Fix???

Post by iondrive »

Hi N,

As always, I'm glad to see you did those tests, but oh no, more questions and tests . :(
But first some talk. The 3rd test above is great news. It tells me that your PJs are putting out full cycles of RGWB and not 2.5 cycles or something odd like that and that is very good. Test 2 is missing the first red but when I do this test, I can see like half a band but it's dim. I think the same is probably true for you too. If you get a good black background, you'll probably see some dim red there. This is dim because the glasses need some time to go from dark to clear.

The red sliver:
Tests 2 and 3 show a red sliver but I also see a red sliver at the end of my color sweeps with my old PJ. I will have to check this with my new PJ. Maybe this is common and I would normally think that it's from the time it takes for the glasses to get dark but you can see this even without the glasses when you use sView with that black and white image. Maybe someday I'll come up with a test to see if it's actually from the current frame's image or the next frame's image but it seems to make more sense that it shouldn't be there. It seems like the right delay circuit could chop this off. Maybe that's the amount of time it takes for the mirrors to go from on to off, but somehow I thought they would be faster than that.

the 85 Hz ink-blotch effect:
Thanks for those earlier links on this. They were interesting and I hadn't heard of it before. I think it's from the glasses changing half-way through the red phase which leads me to my 10th question.

Q10: Would you rather game at 85 Hz? Do the no-glasses black and white sView test at 85 Hz. Get the first and last color and number of white strips in each sweep. If the color sweep goes from red to blue, I think a delay circuit will fix it and you can use it. YAY! Just report anything odd that might be there when you do this test. If things look good, then I'll build you a circuit and hopefully it will work. If you don't want to go this route, then I'll build you a circuit for 75 Hz cause I kind of hate to see you get rid of a good setup and replace three projectors.

Q11: Do you remember how many cycles were in your band of colors? You can just count the white bands in each color-sweep. There should be 3 cycles at 60 Hz but 75 Hz might be 2 or 3. You can skip the 60 Hz check. I'm more interested in the 75 Hz and 85 Hz tests. This question is not that important but I'm just curious to know. It will give me more confidence about what's going on.

Color mismatch:
If both eye-views have the same color pattern, then you do NOT have color mismatch. If you had color mismatch, then one eye would see a different color pattern than the other eye. In my case with my old PJ, one eye sees 6 bands from red to green (RGWBRG) and the other eye sees from white to blue (WBRGWB). That is 1.5 cycles of the colorwheel for each eye. One eye sees too much red and green while the other eye sees too much white and blue. Don't worry about understanding this too much because it looks like you don't have this problem.

Understanding the color cycles:
I think the key to understanding this is to imagine a PJ that has a colorwheel with 4 colors (RGWB, white is just for brightening the image) and imagine that the wheel spins once for each video frame. Do not confuse video frames with the frames-per-second that your game is running at. Game fps could be 30, 90, 4, or anything but your video signal will still put out the same 75 Hz or whatever your display is running at. Just forget all about game fps. If you black out every other frame, then that will cause the dark regions when you spin your pen. In-between the dark regions will be the light that passes through the colorwheel in a sweep that is from just one frame. If it spins once per frame, then you see 4 stripes of different colors. If it spins twice as fast, you see 8 stripes of colors but the stripes are thinner. Oh dang, I forgot to ask if you know about the mirrors. In our case, our DLP projectors work by using a grid of 100's of thousands of microscopic square mirrors that tilt super-fast. Each mirror reflects light from the lamp out through the lens to make a dot on the screen, OR it reflects the light so that it doesn't go out the lens and that results in a black dot on the screen. I guess the colorwheel could be before or after the mirrors to give the white light color. Hopefully that's enough info for you.

Colorblindness???
I still can't figure out why the red would flicker off and on every few seconds. I thought I had an explanation but it doesn't fit your tests. For a while there I thought you might be partially colorblind in one eye. hahaha. Well, I still feel like I should ask. Are you? I would think you would have noticed it by now. That could have explained why the red ghost disappears sometimes.

Yes, I think I should buy that kit from you. I'll PM you. Sorry Dom.

--- iondrive ---
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Re: Parralex Inversion Fix???

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OK THNX for that info.. I have 2 cycles of white @ 75Hz.. I will continue to game at 75hz as at 85 I get a wierd issue with the screen being Chopped off at the edge on the left most monitor right side which totally ruins the picture..

Well as Far as I know I am NOT Partially colorblind or at all. I see Full colors..perhaps it is just a illusion of the red flickering?? I been overtuned to all this stuff now and maybe I imagined the flickering or it was just the scene playing tricks on me???

I will look for it again but have NOT seen it in a while now that I think of it..

OK I'll sell you the kit will check my PM now Thank you.. ;)
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Re: Parralex Inversion Fix???

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From you PM I checked all 3 Projectors they ALL have the Sliver of Red..
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Re: Parralex Inversion Fix???

Post by The_Nephilim »

Ion can you PLEASE check your PM..
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Re: Parralex Inversion Fix???

Post by The_Nephilim »

I sent the Package through USPS Yesterday should be there in a week or so.. but Probally in a week
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Re: Parralex Inversion Fix???

Post by iondrive »

hi,

There's not much new here but I'm considering some different designs. It kind of looks like that red sliver is normal but I think I have a way to test it myself. If it's normal then it might be bad to try and cut it off. We'll see how the tests go once I decide on a design. One option is to try and make it compatible with some 120 Hz PJ that you might have in the future but I think I'll just make it for 75 Hz since future projectors probably won't use old 15-pin VGA connectors.

Some odd questions:

Q12: Do you know binary?
Why? I'm considering a design that let's you select timing delay using binary but it's unlikely I'll choose this idea. Once timing is set, you shouldn't have to change it unless you change your refresh rate but that's true for any design.

Q13: Does your computer have a PS2 keyboard connector or is it USB only?
Why? I might decide to modify an old "Another I" dongle that I have but it needs power from a pass-through PS2 connector. The advantage of this dongle is that you would never need to use ED-Activator. It's basically always on and it already has a "reverse" button.

Q14: Are you familiar with the "advanced timing" button/window on the nvidia control panel? Under the vertical section, you should be able to switch sync polarity to negative. Please try this. It should work fine but you might have no indication that it worked. Basically, if you change it to - and hit "Apply" and still have good video, that means it worked even if the box still has a + in it. If it doesn't work, then do nothing and let the timer time-out to revert to the original setting. You don't have to do this if it worries you but I wouldn't expect any problems.
Why? One of the design options is easier if the pulse is negative instead of positive.

As you've probably guessed, delivery of the kit was not urgent or anything. I'll PM you when I get it.

--- iondrive ---
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Re: Parralex Inversion Fix???

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No I do NOT know Binary.. I have a USB Keyboard and mouse..

I was able to set the Vertical timing to NEgative..
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Re: Parralex Inversion Fix???

Post by iondrive »

hi again,

Hey, I got the kit today and thanks for the extras. Hopefully I can complete the delay and switch circuit within the next two days but Easter weekend might get a little busy. You seem to be a man of action while it takes me too much time to do just a little. Are you gaming with the dongle plugged into the emitter or with glasses upside-down? Now that I have a pair, I see that they don't feel too bad upside-down. I haven't setup the 3dvision yet since I still need to install Vista and configure my system before that. I will work on the circuit first. I think I can do it with just two chips but it'll be set specifically for 75 Hz. I'll test it myself of course as best as I can before I send it. I can just use the same address on the box you sent me, right?

PS2 keyboard port:
It's fine if you use a USB keyboard but does your computer have a PS2 keyboard port? Just look on the back of your computer and see if there are two round ports, normally one purple and one green for the keyboard and mouse respectively. Each port has 6 tiny holes and one small squarish hole for alignment. I think really modern computers don't have these anymore but yours might even though you're not using them. If you have them, I'll probably send you that old dongle I have so that you won't have to use ED-Activator. It's no big deal, I got 4 of them for 5 dollars each before shipping.


Warning: Read the following only if willing to waste time on reading about a crazy idea that probably won't work.

Another crazy idea for fixing parallax inversion: the two kit method
dang, I thought of this idea too late but it might not even work since it's weird. Basically in order for this idea to work, the question that needs answering is this: Can the 3dvision system work with two USB emitters connected simultaneously? One would be like a master and the other like a slave. The slave gets its input through the stereo 3d sync jack and that signal comes from a special circuit. That circuit generates the correct non-parallax-inverted signal by shining a light through one lens of the master glasses and detecting the darkening with a light detector. The light detector outputs a nice square wave that goes to the slave emitter. The glasses themselves provide the proper timing. If it's on the wrong lens, then just setup the light and sensor on the other lens. The master glasses and emitter are hidden in a dark box or somewhere out of sight. Then the two emitters will be 180 degrees out of phase but for maybe some hopefully negligible lag. If it's not negligible, then you still need a delay circuit and this idea is not worth it. Oh wait, I guess instead of two wireless kits, one could try one wired and one wireless. Then the wired glasses could be the master. It's a neat idea but I still think it's a bad one for reasons of cost and it might not work with two emitters, and it uses a pair of glasses that a person then can't use.

sayonara friends
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Re: Parralex Inversion Fix???

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Well I am glad you got the kit and all is well..Take your time on the Little gizmo you are building no rush on that..

I just got another video card so currently I am just wearing the glasses upside down but I am going to put the Inverter back on so I can wear the glasses right..

NO I do NOT have a PS/2 Port.

Yes that does sound like a crazy idea and a little costly wish I knew that before I sent you that kit ;)

Well I will just be good with the Switch/inverter you are going to make and that shoulkd suffice.. Even If that dont work using my current ED Dongle and Inverter seems to work rather well.. just takes a few times turning Stereo Off/On to get the inversion right..

I reallly appreciate all the help and you have motivated me to get this corrected something I have put off for some time hehe!!
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Re: Parralex Inversion Fix???

Post by Dom »

Hey Nephilim, I can comfirm that the Nvidia universal 3d glasses I got from you work with Nvidia 3d Vision and also work as said with the parallax button swap eyes.

Since the glasses we got were defective, the right lens not blinking from manufacturing. The left does show 3d and I can see half of 3d when watching on my projector. Now when I did the 3d wizard setup, where it asks you to pick the shapes I could pick either set because once I pressed the button once and the glasses would swap eyes.

So I am confirming that these glasses DO WORK with Nvidia 3d Vision to swap eyes. And the glasses will stop blinking when the nvidia emitter 3d is turned off.
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Re: Parralex Inversion Fix???

Post by The_Nephilim »

Hey Dom Well I am happy with the way I have it working right now no need to get other glasses..Hopefully somtime in the future I can update these aging Projectors..

Sorry the Late reply but this one slipped by me ;)
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