My DIY desktop "holo" projection thread

[Rallywagon]

Good day GTP members!
So, recently I managed to snag a free Espon projector. It's nothing special. Only 720p, but it works as required. I honestly was hard pressed to come up with a solid use for it until I remembered this neat little trick...

This is created by taping 4 triangular pieces of clear plastic together and setting it on top of a video that is displaying 4 different angles of an object. The effect being a "holographic" projected on the plastic piece.
Now, if a phone display can do that, surely a projector can do better! I've got some sheets of plexiglas that I am going to rig together with some 1x1 wood boards and dowels so I can make an adjustable version of the "window" and set about making a bigger version.
I am planning a large gaming desk that I will be building this into. I have some programming skills, and have friends that are really good at it. The idea is going to be displaying health/mana bar type info. Some games in fact have whole lists of streaming data that mods and such can be built around. I am hoping to get stuff like the holographic map in Elite Dangerous to display.
Custom making some of the displays, or playing videos off youtube for ambience is easy enough. I would like to find a way to make it work a little more universally. I am thinking that creating 4, duplicated displays, each turn 90° from the next would do the trick, but I havent found a good way to do that. Microsoft has a program called Displays. But that makes virtual desktops, which isnt what I am looking to do. (Interesting implications for jumping through different workstations though.)
I need to do a bit more digging. I am sure there is probably a setting or something in the geforce software or something that will let me do what I am wanting. Something simple.
Anywho, if any of you have an idea, please share. For the duplicated display or maybe a use case. I'll keep updating this as I move along in my endeavour.

 

[sesselpupser]

If I've understood this correctly, you want to build a desk with a projector oriented vertically inside it and an inverted pyramid (edit: actually a frustrum) of polycarbonate or acrylic for it to project onto, it'll be projecting the same image four times but each instance is rotated 90 degrees in relation to the one next to it, and you think this will be easy?

I'm an AV engineer in a museum, I get asked to design some weird stuff, most recently I've been asked about a rear projection table that can do an image of about 1x1.5m at 700mm high, possibly with legroom for wheelchair users. Even if your projector can focus closely enough, the throw ratio gives you a suitable image size at the distance you're talking about, isn't so bright even at the lowest setting that it just lights up the entire room or dazzles you when you look at the image and doesn't produce an uncomfortable amount of heat when confined under your desk, the things you'd have to do to make the image look right when projected onto a surface like that even for just one image is probably outside of your projector's capabilities (even installation-spec Panasonics have a limit of about 40 degrees of vertical keystone correction), doing it to four images from a single source would have to be done in software.

Then there's the projector's resolution, it's 720p, you want four images but it's not as simple as dividing 720p by four either because the image correction you need to apply would mean you have to reduce that to a square, then split the square into four, then project a 16:9 image in that subdivision which will give you an effective resolution somewhere between 'bugger all' and 'not enough'.

I may have misunderstood. Can you provide a drawing and the model number of your projector?

Edit: Having thought about it some more, you could write a Processing sketch (or similar) that visualises data pulled from games in pre-formatted shapes so they project correctly, actually doing that is beyond me but you could easily create test patterns to at least get the polycarb/acrylic frustrum aligned properly then work on the rest in your own time.

I think you'll still struggle to align the projector correctly though as they're typically designed so that when placed flat on a desk or inverted on the ceiling, the horizontal edge of the projected image nearest to the lens (i.e. bottom, if on a desk) is in line with the lens, or even higher (lower if inverted). This means the centre of your frustrum won't be aligned with the lens, so the side furthest from the lens will be in shadow.

 

[kikie]

Is this what you mean?

 

[Rallywagon]

Yes, except with a projector instead of a tablet so I can build it on a larger scale

 

[Rallywagon]

Sorry about missing all of this. For some reason they didnt hit my notifications.

If I've understood this correctly, you want to build a desk with a projector oriented vertically inside it and an inverted pyramid (edit: actually a frustrum) of polycarbonate or acrylic for it to project onto, it'll be projecting the same image four times but each instance is rotated 90 degrees in relation to the one next to it, and you think this will be easy?

I'm an AV engineer in a museum, I get asked to design some weird stuff, most recently I've been asked about a rear projection table that can do an image of about 1x1.5m at 700mm high, possibly with legroom for wheelchair users. Even if your projector can focus closely enough, the throw ratio gives you a suitable image size at the distance you're talking about, isn't so bright even at the lowest setting that it just lights up the entire room or dazzles you when you look at the image and doesn't produce an uncomfortable amount of heat when confined under your desk, the things you'd have to do to make the image look right when projected onto a surface like that even for just one image is probably outside of your projector's capabilities (even installation-spec Panasonics have a limit of about 40 degrees of vertical keystone correction), doing it to four images from a single source would have to be done in software.

Then there's the projector's resolution, it's 720p, you want four images but it's not as simple as dividing 720p by four either because the image correction you need to apply would mean you have to reduce that to a square, then split the square into four, then project a 16:9 image in that subdivision which will give you an effective resolution somewhere between 'bugger all' and 'not enough'.

I may have misunderstood. Can you provide a drawing and the model number of your projector?

Edit: Having thought about it some more, you could write a Processing sketch (or similar) that visualises data pulled from games in pre-formatted shapes so they project correctly, actually doing that is beyond me but you could easily create test patterns to at least get the polycarb/acrylic frustrum aligned properly then work on the rest in your own time.

I think you'll still struggle to align the projector correctly though as they're typically designed so that when placed flat on a desk or inverted on the ceiling, the horizontal edge of the projected image nearest to the lens (i.e. bottom, if on a desk) is in line with the lens, or even higher (lower if inverted). This means the centre of your frustrum won't be aligned with the lens, so the side furthest from the lens will be in shadow.

I have been mulling it over some. I'll like mock up a prototype over xmas break when I have ample free time. Right now I have the projector (I'll get the model when I get home) the wood, the plexiglas and the will. I am thinking of going two sides instead of 4. The idea is to have it visible from the desk, so I think I'll only need the front and back panels to achieve the desired effect.
I plan on using the videos on youtube for the phone display version for testing and such, then if it goes well i'll start working with a friend on the software side.

 

[Rallywagon]

Ok, so, I did some playing around with it today. It definitely isnt going to work as well as I would have liked. The light from the projector tends to just shine through the glass rather than reflect off it. What I did instead was shine it up onto a piece paper which has the added benefit of inverting the projection so it reflects in the appropriate direction.
I also cut it down to just one piece of plexiglas. Over all it worked out so so. Built to a desk I think it would end up working alright, but at the end of the day, using a monitor would probably be easier and better.
Here is the imagine when reflected straight onto the plexiglas

This is it when shining onto paper.

This is the whole of the experiment currently.


The projector is under the table. As you can see the table needs to be about 6 inches taller te get good focus.
I am going to play with this some more and also grab my spare monitor and give that a go as well.
All told, the monitor will probably be the way I go, mostly because of the heat and space requirements. I can get a nice clean image without the need of a medium to project onto and through.
But, that does present another interesting idea. I have a moto z play smart phone that my wife broke the screen on and a projector for it. That does project well close. I am going to build a custom PC "case" out of the table above. Might be pretty cool to cast a rear projection onto one of the faces or even the top.
Anyway, I am going to keep on chooching along on this. Maybe have a better resolved prototype to share.

Update:
Ok, so I dug up my old monitor and gave that a try. The result was as expected. It worked out much easier, but I need to play with the image orientation more.
Next step is to fashion up something a little more permanent on one of the sides of my desk. I'll make it so I can swap out the monitor and the projector to give both a solid go. I'll look at something higher quality and thinner to replace the plexiglas. Probably hinge it as well so it can be laid flat when it's not needed.
Anyway, here are some pictures of some ideas as well as a video of the monitor in action.

 

[Rallywagon]

So, I made a more usable mock up to play with. And to be honest, its position and over all effect has made me begin to question its uses. In most cases, a simple monitor is more practical, easier, and provides a better image.
However, I am a fan of novelty. That being the case, I thought on it a while and have come up with a couple of "practical" uses, which I am thinking to use.
So, my first issue is how far outside of my field of view I have the display. I run a triple monitor set up, so the display has to be that far out, which is not convenient for any sort of gaming utility. In fact, I've only been using it currently to display certain Wallpaper Engine backgrounds that look good displayed as such. So, I decided to look more vertically and place it above my main monitor. Might be a novel way to display time clocks and other race stats as well.
The "verticle" theme holds for the second idea as well. That being figuring out a way to throw the display onto the desk, under the keyboard area. I can see that being a neat way to display certain bits of information or complement RGB keyboards and effects. Wallpaper Engine has a few neat bits for this. I havent taken the time to make a wallpaper using it yet, but I am sure there are some gems that can be made up using it as well.
Here is the current mock up. That's right, liberal amounts of hot shmoo and plastic knives!


Anyway, I'll be developing the ideas more. I may have something done later this week for an update.

 

[Rallywagon]

Welp, I didnt wait that long even. Slapped together some cardboard and hot glue and here we are.




Honestly, none of these really do it justice. My earlier doubts have been lifted with the new position. Now I just need to figure out how to "mirror" the image. And make a better frame with better glass.