Film-Tech Forum ARCHIVE: Dolby 3D alternative usage

This is topic Dolby 3D alternative usage in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Jesper Meng (Member # 7575) on 11-24-2014, 04:03 PM:

I have a rental company mostly doing mobile outdoor cinema, 2 screens, ap. 100 shows each summer for almost 20 years. I have two Barco 32B, recently i sold one and ordered a 4K version with Dolby 3D. Maschine 1 is 2K/Doremi IMB/Showvault. The new one is supposed to be Doremi IMS, but i might wait for an IMS2, no jobs in the book right now.
I have made a single 3D show with a Xpand kit, but ended up buying Dolby as i think it is the best solution, for me.
I expect that there will be more 3D shows in the future, and more non -cinema alternative stuff. But i am new to the 3d.....
1) Is it possible to stack the two 32B's 2K/4K for 3d?
2) If so, how is it configured?
3) Does any of you have experience with connecting computers to the projectors for 3D?

Thanks for a great forum, lots of good stuff here.

Posted by Carsten Kurz (Member # 5396) on 11-24-2014, 04:29 PM:

You mean stacking a 2k 32B and a 4k 32B for Dolby 3D?
Should work, as long as you feed both machines through HD-SDI. Dolby has a special colour wheel kit for stacking applications. However, after you built it in, you can't use each projector for Dolby 3D alone as previously. You would need to put the traditional single machine colour wheel back in.

I guess it is possible to stack two traditional Dolby 3D equipped machine with the split colourwheel, but you will not gain as much light as with the special stacking wheel.

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 11-24-2014, 04:41 PM:

Stacking two projectors using the split Dolby 3D color filter wheel will probably never result in an acceptable image. You need to converge two images over each other. Without the help of additional convergence tools (which you can't use because of the ever present encryption), this will simply be almost impossible to get right, especially with two different projectors. The fact that this whole setup needs to be mobile isn't helping either.

Also, using two different projectors, especially a 2K and a 4K machine in a stacking setup isn't something I would want to advice. While it will just work, I doubt it will look good, especially up close. Besides the added difficulty of getting the brightness right between both projectors, the picture of the 4K machine will definitely look different compared to the 2K picture.

While usually almost nobody will notice this, you're now putting them "side-by-side".

Posted by Sam D. Chavez (Member # 1841) on 11-24-2014, 07:16 PM:

quote: Carsten Kurz
I guess it is possible to stack two traditional Dolby 3D equipped machine with the split colourwheel, but you will not gain as much light as with the special stacking wheel.

AFAIK, there are no official single color wheels for Barco. It has been done using modified single color Left eye, right eye wheel kits from Dolby that need customer modified brackets, Barco only sells the split wheel kits. But, perhaps my information is out of date.

Posted by Marcel Birgelen (Member # 6801) on 11-24-2014, 07:25 PM:

While it seemingly doesn't appear on their official product list, I'm sure they have been available for the DP-3000, officially supported by both Dolby and Barco.

Posted by Sam D. Chavez (Member # 1841) on 11-24-2014, 08:10 PM:

Hopefully true but someone still needs to create custom brackets, hopefully someone who knows what they are doing. Imagine the cost of damaged wheels.

Posted by Pete Naples (Member # 761) on 11-25-2014, 01:47 AM:

Marcel, it can and has been done using two standard split wheels.

You need HD/SDI distribution amplifier and both projectors need to be critically picture aligned and balanced for light.

This doesn't give the same light output as Dolby 3D LS solution but does give an increase over a single projector, it also means you have redundancy in case of any failure. It's not uncommon to do this for premieres, festival screening and the like.

Dolby UK can provide technicians and equipment hire for this, I'd imagine Dolby in the US can too.

Posted by Marcel Birgelen (Member # 6801) on 11-25-2014, 02:57 AM:

I know it has been done on a few occasions with XPand's active 3D system, as this is the only way it will work with that system.

I'm wondering, how will this work with encrypted content and a HD SDI splitter/amplifier?

And how do you maintain such a system in production? You'll be constantly adjusting the picture alignments of at least one of the projectors to avoid creating a blurry mess.

Christie does have a DCI dual projector system using an external camera and using their own custom convergence system. (Essentially like the Digital IMAX system.) It also supports Dolby 3D, although I'm not sure if they support it in the split color wheel configuration.

Posted by Carsten Kurz (Member # 5396) on 11-25-2014, 06:36 AM:

Well but stacking solutions for dual or even quad projector 3D are quite common. Yes, they need to be adjusted properly, but that is also true for e.g. a RealD XL unit.

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 11-25-2014, 07:23 AM:

The two images of a RealD XL unit originate from the same light engine and also went trough the same projector lens. Convergence will be less of an issue here.

Stacking and stitching projectors together via edge blending is certainly quite common and has been done since the days of the CRT projectors, but besides the stacked 3D solutions for large screens, not really common for DCI applications. The biggest problem here is the encryption between player/server and projector. IMAX has their specific, non DCI-compliant solution and Christie has a DCI compliant solution.

I'm also still wondering how you can successfully split the encrypted HD-SDI signal coming from a server to two projectors, if you would want to go the "do-it-yourself" route by simply repeating the same signal over multiple projectors.

Similar setups have been done in the past with two servers, running besides each other and keeping each other in sync.

Posted by Jesper Meng (Member # 7575) on 11-25-2014, 08:51 AM:

Thanks for the replies! I guess i must be more precise.
I am trying to define the possibilities with the equipment i have.
The 3D thing is a 'product in development' for me, but it should be possible to use it for premieres, festival, at least, that was the plan.
It would also be nice for me to be able to offer the equipment to other kind of events, for example a dentist convention, i know that they use 3d for visualization.
But has anyone used Dolby 3d for something like that?
In the replies i can see that a HD/SDI distribution is necessary, that means that i have to have a Doremi with a Dolphin card? Does that fit in the showvault?

Posted by Dave Macaulay (Member # 813) on 11-25-2014, 09:14 AM:

You can not have two media blocks on a server - like both an IMB and a Dolphin. You can ask Doremi about this but I have very little doubt about it.
I suppose you could have two projectors each with a normal color wheel projecting Dolby3D® together with the images aligned. That would give you more light - but color setup would become troublesome. As already posted, you need different filter wheels for true two-projector Dolby3D® (one eye per projector) - the wheels are not made to be changed easily although it's not a horrible job in a Barco "B". The wheels do cost a LOT though!
I believe the ShowVault has a "chase" capability to run two-projector 3D: you need two servers, one slaves to the other. Ask Doremi about that, though.

Posted by Marcel Birgelen (Member # 6801) on 11-25-2014, 10:31 AM:

quote: Jesper Meng
It would also be nice for me to be able to offer the equipment to other kind of events, for example a dentist convention, i know that they use 3d for visualization.

Are you sure you would even need a dual projector setup? A Barco 32B (both the 2K and 4K version) is a very powerful projector. With a 6K bulb, you can still light up respectable screen sizes using Dolby/Infitec 3D.

Posted by Carsten Kurz (Member # 5396) on 11-25-2014, 10:44 AM:

Doremi has a training sheet explaining all supported configurations for dual/quad-projector setups - Dual-HD-SDI, Dual-IMB, Dual server, etc.

But the problem for alternative content is not only the projector setup, but the availability of 3D content and equipment for this application. 3D content is not plugandplay. It is nearly plugandplay for consumer media and equipment, but not for pro-stuff. You need to build some expertise before you offer it. A 3D capable DCI system is not sufficient.

- Carsten

Posted by Marco Giustini (Member # 4544) on 11-25-2014, 12:36 PM:

I believe Dolby 3D is limited to 10m-ish with the most powerful lamp.

Can't Jesper use a L/R configuration? That way convergence is not an issue.

Also, Jesper mentions an IMB/IMS configuration. Not sure if Doremi IMB supports a dual projector configuration yet. Dolby don't. I know Qube do, but it't not a device I would recommend.

Posted by Steve Guttag (Member # 268) on 11-25-2014, 12:57 PM:

To run alternate content 3D...you are going to need something like Christie's SKA-3D input scaler...it can take an HDMI source and break its over/under or side-by-side original and output it as left/right eye on the DVI inputs of the projector. At this time, I think it is the only HDCP compliant solution for that.

No matter how you cut it, with a single projector Dolby 3D...you are talking about an 8-10% efficiency. Now if you invest in the Barco 6P laser projector...then you'll have gobs of light (but an empty back account).

Posted by Carsten Kurz (Member # 5396) on 11-25-2014, 02:36 PM:

quote: Marco Giustini
Not sure if Doremi IMB supports a dual projector configuration yet.

Doremi supports dual-IMB for stacking. They needed it for dual-projector HFR, and introduced it right away with their HFR firmware for the Hobbit. Yes, sure it was shaky, but it is supported, basically, even for an unlimited number of projectors, if you want to carry it that far. Doremi has a few support documents explaining the setup for different server/media block types an operation modes.

The Doremi IMB supports consumer 3D formats like side-by-side, over/under, etc. on the HDMI input. So at least a ShowVault system and a split-color-wheel equipped single projector at least technically can be used for different 3D content types, incl. live playout from a 3D workstation. Even 3D gaming.

- Carsten

Posted by Marco Giustini (Member # 4544) on 11-25-2014, 03:57 PM:

quote: Carsten Kurz
Doremi has a few support documents explaining the setup for different server/media block types an operation modes.

Thanks for that. Does it support single eye operation as well?
what do you mean with the above? what do you mean with "different server/media block types", you mean Dolphin/IMB?

Posted by Carsten Kurz (Member # 5396) on 11-25-2014, 04:09 PM:

Yes, Doremi explains different stacking options for traditional HD-SDI, DualIMB/single server, Dual-IMB/dual server modes. The latter they call 'chase mode' and can be extended to virtually unlimited stack numbers, but is, of course, very costly. Chase mode is also used in digital IMAX theaters for HFR presentations.

- Carsten

Posted by Marco Giustini (Member # 4544) on 11-25-2014, 05:49 PM:

Thanks, I did not know that Dolby servers could do that [Smile]

Posted by Carsten Kurz (Member # 5396) on 11-25-2014, 06:37 PM:

Yes, almost everything is now possible with Dolby servers ;-)

BTW - the latest issue of cinema technology magazine has some more details on the Dolby-Doremi acquisition and what it means to the product lines and branding.

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 11-26-2014, 11:02 AM:

quote: Marco Giustini
I believe Dolby 3D is limited to 10m-ish with the most powerful lamp.

It depends on some other factors like the gain of your screen. But I would say results are still good up to about 12~13m. For outdoor situations, you're probably out of luck, as light conditions are usually much more challenging as in a closed environment.

quote: Carsten Kurz
Chase mode is also used in digital IMAX theaters for HFR presentations.

Digital IMAX indeed uses two Doremi servers for their HFR setup. It bypasses their own magic convergence box, as it isn't really needed for 3D. Not all Digital IMAX locations are properly equipped though. What becomes immediately clear though is what their image shaper/converging box is doing: Once digital IMAX shifts into Three-Dee, you can almost always clearly see in the picture parts that have no parallax, that both images aren't perfectly converged anymore.

You can stack virtually as many Server/IMBs as you want, as long as you get matching keys for those servers from the studios.

Still, convergence will be an issue without any kind of screen shaping in between. I know I'm picky and many don't even bother if they're looking at one big blurry mess, but I like my images sharp and detailed [Wink]