Another useless rant about projectors & TripleHead

[Maurice]

Just a year ago, I would have given one of my kidneys and/or sold my soul to the devil just to have the type of visual system that I have now. But now that I have it, I keep finding new annoyances that anyone who does not have such visuals would totally laugh at and wonder what planet I came from.

So here is my latest rant. My projectors (and all projectors I think) have a way to blank out the displays temporarily like during a presentation. Mine do that as well, but with a blank display, I still see a very faint background, i.e. blank is not totally black.

So what is the issue? Well, there is no issue at all when flying in daytime, dusk or anytime there are some ambient lights in the scenery. But, when flying at night, I see 2 lighter strips in between the dark views. These 2 light strips break up the sky and I think seeing monitor bezels instead would be less objectionable even though the light strips are barely visible.

My 3 views are perfectly aligned and there is no gap in between the views where that background shadow lies, but that shadow somehow lightens the space between the views since that light background shadow is not warped by Nthusim like the rest of the view. This is hard to explain properly so I included a drawing that illustrates the issue.

Now, what really, REALLY bugs me about this is not so much what I see but the fact that this is bugging me at all. I should be thrilled with all I have but I'm now nit-picking and looking for any minor flaw so that I can be unhappy about it. This flight simulation thing is a sickness I tell you. Where did I lose my sanity? 

Anyway, does anyone else with 3 projectors notice this 'flaw'. I don't know if the projectors or the TripleHead causes this but one of them is the culprit here. I just hope that I will get used to this & not restrict my flying to only daytime or dusk. 

Maurice
Edit: See better pictures below

[bussgarfield]

O'h Maurice, my heart goes out to you !!!!

Here I am having my own problems with 3 monitors and your worried about a few light gaps - LOL.

It is very interesting though having read your rant and the other thread currently on the go about TripleHead and Nthusim as one day, just one day I will like to be able to go down the road of having projectors too and what you and others have said proves to be a very interesting read. It is a way of doing ones homework before spending the big euros (bucks) to create that once in a life time immersive experience.

As for a solution to your problem, I have no idea !!!!

Gary

[Maurice]

O'h Maurice, my heart goes out to you !!!!

Gary

I know...my heart bleeds for me too 

Maurice

[Vectro]

isn't this just normal edge blending problem where two video projector images are on top of each other? Nthusim don't support edge blending.

[Kennair]

If I understand correctly this looks like projector overlap at least in between the screens, not sure about the surrounding light however.  We use Sol7 which has edge blending so the increased light intensity at the overlaps can be tweaked out.

Ken.

[Maurice]

isn't this just normal edge blending problem where two video projector images are on top of each other? Nthusim don't support edge blending.

I don't think this has anything to do with edge blending but more to do with the fact that a projected blank image is not really black but has some residual light. I guess the projectors are not able to totally blank a projected image. It is possible that edge blending might mitigate the problem and maybe Nat will chime on this since he is using Sol7 instead of Nthusim (assuming Nat had the same problem with Nthusim of course).

Here are a few shots that show the problem better.

Maurice

[ivar hestnes]

The white stripe you can fix with edge-blending. Where the projectors overlap each others, the light intensity is doubled compared to the "darker" area of your visual. The "ovals" you cant do anything with, except for masking your projector lens. The warping software does only warp the image sent from the computer to the projector, so the projector still has a lightbulb that will try its best to light up your room.

[Vectro]

Referring to the pictures this is normal overlapping of 2 video projector images. Like Ivar said, once there are 2 projector images on top of each other it makes the picture 50% more lighter in this area. SOL7 does have solution for this, called edge blending. You can reduse the lightning of a certain areas in the video projector seams and this way you can get rid of these overlapping light areas.

Check out this link of our early testings and you can see this same effect:
http://www.lentosimulaattori.1g.fi/kuvat/Visual+system+testing/016.JPG

same thing here:
http://www.lentosimulaattori.1g.fi/kuvat/Visual%20system%20testing/018.JPG

We solved this problem by placing the video projector pictures the way that there are no overlapped areas at all. The perfect solution would use edge blending but at least we don't have overlapping areas anymore.

Unfortunately in Nthusim there is no edge blending available and when I asked this from their support they are not planning to bring it in the future versions either.

One solution is 'hardware' edge blending plates that you can set in front of the video projectors. It will make the picture dimmer from these overlapping areas.
Here is a picture:

[Maurice]

The white stripe you can fix with edge-blending. Where the projectors overlap each others, the light intensity is doubled compared to the "darker" area of your visual. The "ovals" you cant do anything with, except for masking your projector lens. The warping software does only warp the image sent from the computer to the projector, so the projector still has a lightbulb that will try its best to light up your room.

Ahh!!! So this is normal then. I would not have thought that edge blending could get rid of the white stripe and would only work with the actual real projected image and not the fake background light which creates the stripe. But I will take your word for it and start the process of convincing my wife the stripe is unacceptable  . That should be a real challenge   

Thanks,

Maurice

[Maurice]

One solution is 'hardware' edge blending plates that you set in front of the video projectors. It will make the picture dimmer from these overlapping areas.
Here is a picture:

Does this actually work? And if it really does, which projector(s) should these plates be added to and where do you get them (homemade?)?

Maurice

[Vectro]

Unfortunately I don't have more info concerning these plates. This just came up in a Finnish builder forum where we have been discussing about this same issue before.

If I have understand correctly as the blend plate is a saw shaped it lets 50% of the image goes through and blogs another 50%.
This way it would be logical to set one edge plate to each projector and place them so together they create one concrete picture.

Maybe something like this:

[Maurice]

Referring to the pictures this is normal overlapping of 2 video projector images. Like Ivar said, once there are 2 projector images on top of each other it makes the picture 50% more lighter in this area.

I understand what you & Ivar are saying but the actual projected images from the projectors are not overlapping at all in my case. If I just use the projector's alignment grids, the grids are not overlapping at all, so this is what is puzzling me. It is only with a blank image that the projection area seems to get bigger, thus the overlap from the blanked projection bulbs.

Maurice

[Vectro]

If you look closely this professional simulator visual from Frasca, you can see that this is exactly how they have solved the problem by masking overlapping areas with blend/mask plates in front of the projectors:
http://www.cwu.edu/~aviation/images/Baron.JPG

[Maurice]

If you look closely this professional simulator visual from Frasca, you can see that this is exactly how they have solved the problem by masking overlapping areas with blend/mask plates in front of the projectors:
http://www.cwu.edu/~aviation/images/Baron.JPG

Hmm! Very interesting indeed.

Thanks,

Maurice

[Vectro]

BTW, are you using any kind of warping correction program, like Nthusim. Without any correction our view looked like this:
http://www.lentosimulaattori.1g.fi/kuvat/Visual%20system%20testing/012.JPG
(very similar to your drawing, with even those round curves on top of the each projector).

Once the same view is runned via Nthusim correction, you can see the difference:
http://www.lentosimulaattori.1g.fi/kuvat/Visual+system+testing/016.JPG

[ivar hestnes]

Referring to the pictures this is normal overlapping of 2 video projector images. Like Ivar said, once there are 2 projector images on top of each other it makes the picture 50% more lighter in this area.

I understand what you & Ivar are saying but the actual projected images from the projectors are not overlapping at all in my case. If I just use the projector's alignment grids, the grids are not overlapping at all, so this is what is puzzling me. It is only with a blank image that the projection area seems to get bigger, thus the overlap from the blanked projection bulbs.

Maurice

Is your resolution set to the projectors native? And your projector menu also have a setting for 16:19, 16:9, 4:3 and Auto I guess. This must be done correctly on both projectors and desktop/resolution, or you risk to get a compressed image, while the lightbulb still force the light through its native resolution.

Hard to explain...

[XOrionFE]

I have the same issue Maurice and I know to solve it I need to get my projectors aligned better to really minimize any overlap and then use masking like this but frankly I hardly notice because I am too busy inside the cockpit trying to setup approach and such :-)

Scott

[Maurice]

Referring to the pictures this is normal overlapping of 2 video projector images. Like Ivar said, once there are 2 projector images on top of each other it makes the picture 50% more lighter in this area.

Is your resolution set to the projectors native? And your projector menu also have a setting for 16:19, 16:9, 4:3 and Auto I guess. This must be done correctly on both projectors and desktop/resolution, or you risk to get a compressed image, while the lightbulb still force the light through its native resolution.

Hard to explain...

I'm pretty close to 100% sure my settings are correct but I'll 'triple' check anyway  . The picture below shows that the projector's grids are not overlapping in any way.

Maurice

[Maurice]

I have the same issue Maurice and I know to solve it I need to get my projectors aligned better to really minimize any overlap and then use masking like this but frankly I hardly notice because I am too busy inside the cockpit trying to setup approach and such :-)

Scott

I know exactly what you mean. I'm waisting a lot of time on this nonsense while the rest of my sim is sitting unfinished. As I said earlier, total madness this hobby 

Maurice

[Maurice]

BTW, are you using any kind of warping correction program, like Nthusim.

Oh yes. See the other pictures I posted here:
http://www.cockpitbuilders.com/community/index.php?topic=1385.msg10570;topicseen#new

[fdspcos]

If I may..
When you use any "keystoning" the first thing you will notice is that the image you want to see is adjusted to align correctly. There is "leftover" light from the projector. This is what you are seeing Maurice.
In the Pro Setups we did when I was in the Aerospace job years ago, you had to use "Blocking Plates" like Vectro mentions above. this is a critical component and always visible in the big setups. This is part of the process.
When you Keystone, you are not blocking the original outout of light.. simply adjusting how the image will be seen. you have to get rid of that extra "blank" light.
good call from Vector on that.
PC

[XOrionFE]

Ah, interesting Peter,

That is why it is important to remove any keystone correction....
I always wondered why that was such a big deal and now I know.    When I started my projector build I was told to avoid keystoning at all costs (probably by Ivar).   I didnt know why but of course complied with the suggestion and made sure I had zero keystoning and now it makes perfect sense why that was important.   I dont have the same level of effect as  Maurice as mine has about a one inch white stripe top to bottom because of the fact that I purposely overlapped mine this way to avoid having a blank split between sections.  I dont have a wider overlap at the bottom like Maurice because I dont have any keystone.

Makes perfect sense and thank you for the enlightenment.

Scott

[Vectro]

Yes,
I also agree that it is important to overlap the pictures a bit. This way you don't have any 'empty' space. You can easily overlap so little that it is
hardly visible. For us there is even a windshield with some scratches etc. so you can hardly see the limits.

[Maurice]

If I may..
When you use any "keystoning" the first thing you will notice is that the image you want to see is adjusted to align correctly. There is "leftover" light from the projector. This is what you are seeing Maurice.
In the Pro Setups we did when I was in the Aerospace job years ago, you had to use "Blocking Plates" like Vectro mentions above. this is a critical component and always visible in the big setups. This is part of the process.
When you Keystone, you are not blocking the original outout of light.. simply adjusting how the image will be seen. you have to get rid of that extra "blank" light.
good call from Vector on that.
PC

Well, I spent a bit of time testing and indeed, you have hit the nail right on the head. The one thing that happens when you get rid of the keystoning though is that you cannot butt the edges of the image along the entire height of the image. So you end up with gaps that Nthusim cannot fill. BUT, it you physically move/rotate the projectors so that the vertical edges are aligned, you can then use Nthusim and straighten everything out.

This also explains why I never noticed that at the beginning. I had not done any keystoning correction at first and I never noticed the light band. But after I 'refined' the alignment & use keystoning correction, this problem showed up but I thought that it was always there and that I hadn't played close attention because I was so excited about seeing a full 210 degree view.

So, I got rid of that light strip after all without edge blending (my wife will be very relieved  .

A BIG, BIG thank you Peter for your help. I should have known you would have some answers or suggestions 

Maurice

[ETomlin]

My 2cent worth- there is a close friend/peer that had also told me about using a limiting device on the projector (refering to them as "barn doors") after seeing this employed at Bell for a helicopter sim that they had and it, as Peter Cos mentioned, works very well.