Projectors

January 09, 2012


Projectors setup


Optoma GT720 is a nice short throw projector 3D-capable at 1280x720 3D at 120 Hz.

It is cheap enough (I bought them for $670 CDN each) therefore there is no lense shift and zoom.
In general I found it not the best choice for the sim projection, especially in a small room, because of the short throw = 0.72 is not small enough for projector placement convenience.

It turned out that no matter what screen radius you choose, all three projectors need to be placed in the same spot very close to the center point.




 Projectors with throw rate ~0.5 can be placed more apart and closer to the screen and do not interfere with each other position that much.

Placing projectors beside each other results in some image distortion on the far left and right sides, where the distance from the lens to the screen is smaller.

I expected that from the preliminary screen calculations and that is the main reason of my flexible screen design where I can adjust the shape of the screen.

The throw angle of GT720 projector is 69°, so theoretically it can cover ~ 210° of screen. However, with image overlapping needed for edge blending it reduces to ~ 180°. Looks like, short (~0.5) throw projectors have the advantage here too.

Beside the projectorcentral.com Projector Calculator
http://www.projectorcentral.com/Optoma-GameTime_GT720-projection-calculator-pro.htm







I also use these two convenient sites for the screen parameters calculation.
http://www.cleavebooks.co.uk/scol/calsect.htm







and http://www.visualtrig.com/



To overcome the absence of the projector zoom I developed the moving base platform with the rails for each projector. Initially they looked like this:










The rails are made from the standard folding closet door rails that can be purchased from any hardware store for about $5.




The base is made of the standard particle board piece, plus I added pieces from plastic kitchen cut board to achieve 22 mm height exactly fitting the door rail. The door rail fixed to the main base board with aluminum angle profile.





The projector mounts I’ve bought allow for a low projector placement. The included extension piece has the standard 1/1/2 thread and can be replaced with a threaded steel nipple of desired length from the plumbers section of any hardware store.





So, to overcome the image distortion problems I placed central projector lower and two side ones above it as close to center as mounts allow.










Along with changing the screen shape that gives me roughly equal distance from lenses to the screen. The slight shape distortion can be compensated by image warping software. And if there is still a little bit of distortions they are at the far ends of the screen, at the peripheral of the view.

My ceiling is only 235 cm height and that presents extra problem since the increased height of the projectors “2-storey” placement may interfere with the top of the 737 shell which is 183 cm,( according to FDS data) and should stand on ~ 8 inch simulator base. Can’t say for sure right now, but it looks they may overlap by a few centimeters – may be I will have to move the shell a bit back from the screen. If you have the ceiling height over 8 ft, that should not be a problem.

*******


January 24, 2012


After getting my failed projector back from warranty service it was time to do the final projectors adjustments and initial test for image warping/soft blending.  Warping/blending operations will be repeated when the projectors are placed on the ceiling, after they are fine tuned and tightened up.

The screen shape adjustments that I did to decrease the distortions at the ends of the screen succeeded completely. There is no image distortion on the left and just slight one on the right.







The relative projectors arrangements are also finalized. Here is a picture with the dimensions and angles.
Physical projector positioning on the base depends on projector size and mounts adjustment range.














As you can see, side projectors’ mounts moved to the corner as far as possible and the center projector mount is practically in the middle.

It is very difficult to design the projector arrangement just “theoretically”ahead of the test and before the actual mounts are installed. This should be done by trial and error. You might find the perfect position is not available because one projector leg hits the side or top of another projector. In case of GT720 you cannot just unscrew the projector legs and take them out. Pity, it could have saved me ~ 1cm of height.

 So, my projector rails were not screwed completely in until the last moment. If the projector positioning is tight (and it will be, especially for smaller rooms), you should also take into consideration the input/power cables placement – they may interfere with each other, or prevent the projector moving in rails:




***********


Image warping

January 26, 2012

For image warping and soft blending I use ImmersiveDisplay Lite 2 ( started with version 1.9). This program is amazing for what it does.

As you know already I have Optoma GT720 projectors and Matrox TH2Go Digital Edition. The projector native resolution is  1280 x 800, according to the specs.






I noticed that the projector without the signal has bigger lighted area, compared to its 1280 x 800 picture size. Interestingly enough, the TH2GO Display Properties suggest resolution of 1280 x1024 as default for it.




Here are the projected pictures of unwarped image. I specifically increased gamma/brightness here to show the areas that fall on the black frame around the screen.









Also want to note for the people who never did the warping before, that typical sample warping  pictures on actual software sites or in manuals may be confusing misleading.
What shown there as a sample of warped image is not what you see on your projection screen and not what you work with. Here is the picture form Immersive Display site:



The picture they show is the image after warping - how it looks on the FLAT screen, not on curved screen. You almost never see that image unless you move the warped picture on your flat auxiliary monitor, (if you have one). I guess they put these pictures up just because it’s easier to do a screenshot from the PC, then bring the camera and make the actual picture from real projection screen. Sure it’s obvious to the developers, because they know what they are talking about, but may be confusing for the first-time users.

To have the auxiliary monitor in addition to projectors is a really good idea. Since the initially projected image is warped “the wrong way”, it is really difficult to operate with Windows menu bar, since it typically falls onto screen support structure outside the actual screen where it’s hard to see. I have the Windows taskbar moved to the flat monitor and docked there.

So, when you have the projected image like this:




you need to fit that crooked image into your curved screen. You may lose resolution pixels in vertical direction as a result, since both lower and upper image borders are curved, one more than another. Note also, that the pictures I show were done in “projectors on the floor” position.

Obviously, with the projectors on the ceiling the curves of the projected image will be upside down – greater curve on bottom of the image and smaller curve on top.  There will be still highlighted areas above/under your screen even after warping – which might not be too bad on the black material. For this light bleeding issue there is a special “Mask” feature in the Immersive Display program that will apply another user-created image, masking those areas so the light just does not go there from the projector.

Before “Mask” feature the only other option was to build a physical mask around the projector lens to block the unwanted light areas.

Here are my current settings for the display properties and Matrox GXM software.









Note “Swap Displays” button in the above picture. Do not try to use it. It is evil.   After cycling through it, the Matrox output completely ignored my left projector. While the Windows Desktop was still working, the Immersive Display warping program was starting display from central projector, no matter what settings were. I had to completely reinstall Matrox GXM software to put things back to normal. So if you want to swap projector inputs – just reattach the input cables appropriately.

When starting your warping - do not use the mouse to move the adjustment points. At least until you get the hang on it.  It is far more precise and convenient to move adjustment points with arrow keys. Left-Right-Up-Down arrows move from point to point, Ctrl+Left, Ctrl+Right, Ctrl+Up, Ctrl+Down - move the points it the desired direction. For the initial warping you only need to adjust points vertically, and using the mouse you can easily mess the horizontal point position without you noticing it.

Here are the pictures illustrating the warping. I used 6 x 6 points grid. Note that Immersive Display dialog box is not warped along with the actual picture, so you may move it to the screen position where it’s easier to read.

Left screen adjusted, working on central:





Left and central screens adjusted:



All screens adjusted:




I found the most convenient to adjust on the default image with text lines. Then I checked on all other images:











All process including projector images positioning/sizing/alignment, then warping and some edge blending took me about 3 hours. The projection now covers the whole screen with 700 cm arc, which considering the current projectors position, gives 200 degrees field of view. Image overlapping for the edge blending is only 5%. I know it is recommended up to 20% overlapping, but I just do not want to sacrifice that much of the screen estate. Will see.

I also quickly tried the soft edge blending.

–here is the picture without blending:



- and here with some blending applied:





What you adjust for blending is -  Overlap % in the first box. When you change this value you will see the overlapping part moving and you must make sure the image in that area matches.

The second box  - Fade %  adjusts the gradient on the blending area. This requires more tests with both daylight and night pictures in FSX. The trouble is that what might blend perfectly in daylight picture may have highlighted areas around in the night picture. I just did it for All colors – however you may adjust color values separately.

For one blending area you adjust it from both sides, for example Right side on the left projector and Left side on the central projector.

You will also need to additionally adjust the alignment points vertically near the blending area.











Correct blending sure will take more time than warping – you cannot rely only on how it looks in Immersive Display only.

This was just a quick test; the blending will be finalized after moving the projectors to the ceiling.

*******

May 30, 2012

Moving the projectors up on the ceiling.

Moving the projectors to the ceiling requires more than one person – not enough hands. J
The projector base is 60 x 117 cm. I could be made smaller after the projectors placement adjustments, however I needed to hang it on more than one ceiling joist which are ~ 16 inches apart. Mounted projectors weight per asssembly: 4.6, 4.6, 4.2 kg, projector base (with rails) weight - 9.2 kg.

After the projector adjustments were done I marked the position of the central projector lens on the floor.
Then I used plumb line to match this position on the ceiling. Also, marked the position of projector base front edge and placed the masking tape on the ceiling along the line.

I used the stud finder to find out the joists positions, and then drilled small holes through the ceiling to pinpoint the joists edges. Next, I chose more or less central hole position  (relative to projector base front edge marked on the ceiling with the masking tape) and placed my rotary laser level under it (it also gives the vertical laser beam). I pointed the laser into the hole and then lifted the projector base and put it to match the front edge line and the central lens mark. While I was holding it, my wife quickly marked the laser dot position with a pencil.

Then I’ve put one 12 x 4 screw through and loosely fixed the base to the ceiling.
Next, I turned the base around the screw so the next hole showed up. Then I repeated the operation with laser pointing the hole and marking its position on the base. After doing so for all holes I drilled through and screwed the whole base in several places to the joists. In general, after you marked two holes along one joist you can just project the joist line and place the additional screws in it. Laser pointing definitely beats the work with a measuring tape for such task...



It took only one evening to put the projector assembly up. Then, of course I had to redo the warping again.
I also tested NTHUSIM trial for the warping, and in terms of picture quality I personally did not find any difference compared to my Immersive Display Lite. The initial warping setup in NTHUSIM looked a little faster, however I found overall possibilities of fine picture adjustments are far better in Immersive Display Lite (in my opinion). Also want to mention that I abandoned the soft edge blending whatsoever and found  the precise windows positioning with no overlapping a better option. Thus I got a wider overall picture that now covers 204 degrees - 3 docked windows of 68 degrees each, which matches the physical projector throw angle.

I also spent about 3 weeks playing around FSX/Nvidia Inspector settings to get the acceptable frame rates. The PC now is overclocked to 4.6 Ghz.

So, now I have ~18 FPS on the runway at ORBX Cairns runway, that I use for the performance tests. But the optimizing looks never finished, I still try new and new settings. I am OK with ~17-18 FPS, but still work trying to get a better picture and reduce blurries and artifacts.

Here is test flight around Cairns.




I also completely blacked out the sim room in order to reduce reflections from the ceiling and walls. I did not intend to use any black paint for that and used cheap black landscape fabric instead.



It may look like I destroyed the whole room, but in reality there are only 7 small holes in the ceiling that hold the projector assembly. There is no more damage to the walls than from hanging a couple of wall photos – that’s it.  The black masking is not attached to the ceiling – one end of its supports is attached to the projector assembly and the other ends just lay on the screen support structure, that in turn just stands on the floor. The whole room black masking can be removed in five minutes without a trace. There are two fans installed on the ceiling that blow away the hot air from the projectors.







May 14, 2013

My testing of 3 windowed views (not 4!) approach


The latest visuals approach I tried was using 3 views instead of 4 that Windowmaker creates. (link to original Windowmaker thread here:


This approach is based on recent thread here:  http://prosim737.com/forum/viewtopic.php?f=41&t=3837

and  here:


Note: Actual discussion thread is here: 
http://www.cockpitbuilders.com/community/index.php?topic=3361.0   There you can download files and  see the screenshots of my FSX settings that I always use for visual tests.


I did not invent this approach, I just hope I could explain it better here than it is in original threads. It took me quite some time until I could get it working right.

So, here is what I did.

I use ProSim Jetstream 737-800 model now.

First, I've set 2D cockpit in FSX configuration.
Next, I did the following changes in Jetstream panel.cfg (\FSX\SimObjects\Airplanes\Jetstream_738\panel\panel.cfg). 
Those are the only enabled lines in panel.cfg now:

/////////////////////////////////////
[Window Titles]
window00=Main Panel

[Window00]
file_1024=Boeing.bmp
size_mm=1024
position=7
visible=1
ident=MAIN_PANEL
//////////////////////////////////


Next, the file boeing.bmp (see link for  attachments below) is placed to \FSX\SimObjects\Airplanes\Jetstream_738\panel folder.  This file is the transparent main panel and the actual trick that allows not to use 4th window.

Below are the following changes to view/camera definitions in default flight .FLT file.
Note, only 3 views are used, not 4.  Zoom value is still same as calculated by Windowmaker spreadsheet. 
Note also, that the proper sound belongs to 
Center view. If you accidentally click on one of side views it will make it active and sound will change.

//////////////////////////////////
[Window.1]
Order=2
Active=False
Undocked=False
Maximized=False
ScreenUniCoords=2731, 0, 2731, 6144
UndocCoords=0, 0, 0, 0
CurrentCamera={B1386D92-4782-4682-A137-738E25D1BAB5}

[Camera.1.1]
Guid={B1386D92-4782-4682-A137-738E25D1BAB5}
Zoom=0.447647365534387
Title=Center view
Translation=0, 0, 0
Rotation=0, 0, 0

///
[Window.2]
Order=0
Active=False
Undocked=False
Maximized=False
ScreenUniCoords=1, 0, 2731, 6144
UndocCoords=0, 0, 0, 0
CurrentCamera={B1386D92-4782-4682-A137-738E25D1BAB5}

[Camera.2.1]
Guid={B1386D92-4782-4682-A137-738E25D1BAB5}
Zoom=0.447647365534387
Title=Left view
Translation=0, 0, 0
Rotation=0, -68, 0

///
[Window.3]
Order=1
Active=False
Undocked=False
Maximized=False
ScreenUniCoords=5461, 0, 2731, 6144
UndocCoords=0, 0, 0, 0
CurrentCamera={B1386D92-4782-4682-A137-738E25D1BAB5}

[Camera.3.1]
Guid={B1386D92-4782-4682-A137-738E25D1BAB5}
Zoom=0.447647365534387
Translation=0, 0, 0
Rotation=0, 68, 0

//////////////////////////////////


Compared to 4 views version , that I used before (generated by same Windowmaker spreadsheet).

////////////////////////
[Window.1]
Order=0
Active=True
Undocked=False
Maximized=False
ScreenUniCoords=1, 1, 4, 4
CurrentCamera={C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}

[Camera.1.1]
Guid={C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}
Zoom=255
Translation=0, 0, 0
Rotation=-90, 0, 0

[Window.2]
Order=2
Active=False
Undocked=False
Maximized=False
ScreenUniCoords=1, 0, 2731, 6144
CurrentCamera={C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}

[Camera.2.1]
Guid={C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}
Zoom=0.447647365534387
Translation=0, 0, 0
Rotation=0, -68, 0


[Window.3]
Order=3
Active=False
Undocked=False
Maximized=False
ScreenUniCoords=2731, 0, 2731, 6144
CurrentCamera={C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}

[Camera.3.1]
Guid={C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}
Zoom=0.447647365534387
Translation=0, 0, 0
Rotation=0, 0, 0


[Window.4]
Order=4
Active=False
Undocked=False
Maximized=False
ScreenUniCoords=5461, 0, 2731, 6144
CurrentCamera={C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}


[Camera.4.1]
Guid={C95EAB58-9E4A-4E2A-A34C-D8D9D948F078}
Zoom=0.447647365534387
Translation=0, 0, 0
Rotation=0, 68, 0
//////////////////////////////////



For visual tests I always use ORBX Cairns International airport. It is heavy scenery with mountains (lots of autogen trees) on one side, sea on another side and many buildings below with takeoff in either direction. 

No internal/external FPS limiter is used.
[BUFFERPOOLS]
Poolsize=0


My videocard is GeForce GTX 570. 8 GB RAM and two SSD drives.
Processor I7 2600K Sandy Bridge with hyperthreading off, overclocked to 4.6 GHz

Below are my FSX settings that I always use for visual tests. (see in the linked thread below)

And also here is how the screen looks like (screenshot in windowed mode) when I move center window window off a bit. Instead of maximized full-screen 4-th window below there is just a black area. ((see in the linked thread below)

I also attach my fsx.cfg and default FLT file used in testing for your reference. 

My results of this switch to 3 views are: 

Before: with 4 views version  I had 17-18 FPS on takeoff in Cairns.
Now: with 3 views version  I have 22~24 FPS. on takeoff in Cairns.

After takeoff FPS quickly go over 30.
On landing FPS were often dropping to 13-15 before. Now they might drop in 18-20 range.

So I definitely see the improvement with this 3 views setup. 

Note: Actual discussion thread is here: 
http://www.cockpitbuilders.com/community/index.php?topic=3361.0   There you can download files and  see the screenshots of my FSX settings that I always use for visual tests




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