Space Invaders 'reflector' cabinet question.

[jukingeo]

Hello,

I am looking to build a custom 'bartop' Space Invaders cabinet.  It will run off of a computer board and Mame, but the one thing that is nagging at me is how to duplicate the 'mirror' set up that was used in both the original Space Invaders 'reflector' Midway cabinet and also Space Invaders Deluxe.

I have worked on 'reflected' cabinets before where the monitor was located in the lower part of the cabinet and the video was reversed.   Then in the upper part of the cabinet there was a mirror that reflected everything back to the player.  While I understand this concept fully, this really ISN'T the same as Space Invaders.   Space Invaders allows you to see THROUGH the 'mirror' at a 'backdrop'.   This makes the Invaders to have that 'hovering' ghost look.  THAT is the effect I would like to duplicate.

Unlike other mirrored cabinets, I am thinking that perhaps Space Invaders doesn't use a mirror at all, but a very reflective piece of glass.  This would allow a good reflection as well as being able to see through it.  If that is the case then the effect would be based on the popular "Pepper's Ghost" effect.  So let me know if I am on the right track here.

Now, another thing that comes to mind is the backdrop itself.  I am guessing that this is lit up somehow.  So I would need info on that as well.

I am posting here in the restoration thread because I am sure that there are several of you that perhaps restored a Space Invaders cabinet and I am wondering if you could share some pictures with me as to how this effect was done in the Space Invaders cabinet.  Pictures are worth 1000 words, so that is probably the best way to learn how this is done.

Overall the plan is to duplicate the top portion of a Midway Space Invaders cabinet, but on a smaller scale so I can place it on a table, shelf or counter.  I was going to use a 15" flat screen monitor and orient it the same way as it was in the original SI cabinet.

Any tips and pointers would be appreciated.

Thank You,

Geo

[SirPeale]

It's called a "two-way mirror"

[Kevin Mullins]

Also called a "half silvered" mirror.
Ask a glass shop about it .......

[jukingeo]

It's called a "two-way mirror"

Also called a "half silvered" mirror.
Ask a glass shop about it .......

Ok, but how is it oriented in the cabinet?  Silvered side to the front or back?   How is the backdrop set up?

I have not seen the inside of a Space Invaders cabinet so I don't know how it is set up, in fact it has been a while since I even PLAYED the game in an original Midway cabinet.  This is the reason WHY I posted in the restoration section (yes, there is method to my madness), because I am sure those that have restored a Space Invaders cabinet could provide those pictures.   So I didn't exactly appreciate finding that my post was moved here instead, since it is probably a person that restored an SI that could help me the most.

[Kevin Mullins]

Well, if it's like an Asteroids Deluxe the "mirrored" side would face you. (really hard to tell the mirrored side, but there is a difference)
And ad far as "how"...... we'll have to visualize here.

Draw a square.
Now draw a diagonal line through it from top right to bottom left.
Artwork would be on the left side facing the right.
Monitor would be on the bottom facing up towards the mirrored side of the glass.

What the exact angle is, I'm not sure. But that's the concept anyways.

[jukingeo]

Well, if it's like an Asteroids Deluxe the "mirrored" side would face you. (really hard to tell the mirrored side, but there is a difference)

Ahhh, Asteroids Deluxe....yes, that would be another one that would work the same way.

And ad far as "how"...... we'll have to visualize here.
Draw a square.
Now draw a diagonal line through it from top right to bottom left.
Artwork would be on the left side facing the right.
Monitor would be on the bottom facing up towards the mirrored side of the glass.

What the exact angle is, I'm not sure. But that's the concept anyways.

Yeah, I had an idea of the concept myself because I have worked on mirrored cabinets before, such as Pac-Man.  But those cabinets were a full mirror.   The element I am missing is how the backdrop is laid out and the EXACT measurements for the angles.   Like I said in my OP it would have been great to see pictures of the interior of Space Invaders so I could see for myself, that is why I originally put this post in the restoration section because that is the kind of person that could help me best.  BUT, one of the moderators decided to move my post here.  Naturally I am not too happy about that.

But to anyone that is reading this it does appear that Asteroids Deluxe also has the same kind of mirrored set up, so if you have an Asteroids Deluxe that you can take pictures of to help me out, that will do fine.

Now that I recall, I believe Space Invaders Deluxe also had the mirror / back drop of it's original cousin.

Thanx,

Geo

[cosam]

Like I said in my OP it would have been great to see pictures of the interior of Space Invaders so I could see for myself...

If you have the patience (this is one long page with lots of photos) have a look here for the deluxe version.

[jukingeo]

If you have the patience (this is one long page with lots of photos) have a look here for the deluxe version.

Hello Cosam,

Thanx a bunch for the link to the pictures.  However, after looking at them, I now have more questions than answers. For starters, do you still have the machine?

Would it be possible to to take 'layered' pictures?  In other words, remove the front bezel to show the mirror, then remove the mirror to show the positioning of the backdrop?   How does the bluish half-round piece go?  In your pictures it looks like it is very well towards the back of the cabinet.  But what I was curious about is if it is in front of, or behind the black light.   Stuff like that has me a bit confused.

Finally, the angles of the monitor v.s. the glass do look weird, but yet are similar to other angled mirror cabinets I have seen.

Supposedly the mirror/monitor are not on even angles.  The monitor actually faces the rear of the cabinet more than straight up.   That is understandable as you don't want the player to see any of the monitor on the bottom there.   Thus now to maintain the proper reflection angle, I would assume that the mirror is sitting at a 45 degree angle to the monitor tube.

Next is the issue of the silvered side of the two way mirror.  Does the silvered side face the front of the cabinet (I am assuming so), or the rear.

Stuff like that,

Thanx for the info,

Geo

[cosam]

Thanx a bunch for the link to the pictures.  However, after looking at them, I now have more questions than answers. For starters, do you still have the machine?

Sorry, it's not my cab, just something I came across on the web. Maybe you can find some contact details on the site somewhere.

Finally, the angles of the monitor v.s. the glass do look weird, but yet are similar to other angled mirror cabinets I have seen.

Supposedly the mirror/monitor are not on even angles.  The monitor actually faces the rear of the cabinet more than straight up.   That is understandable as you don't want the player to see any of the monitor on the bottom there.   Thus now to maintain the proper reflection angle, I would assume that the mirror is sitting at a 45 degree angle to the monitor tube.

I don't think there's any reason it'd have to be 45 degrees. All you need to do is make sure the monitor is reflected somewhere in the field of view of the player. If I were building it, I'd either make a mock-up and experiment, or make the end product adjustable (at least the angle of the mirror, if not the monitor too).

Next is the issue of the silvered side of the two way mirror.  Does the silvered side face the front of the cabinet (I am assuming so), or the rear.

I'm no expert on the subject, but I'd have thought the silvered side would be away from the viewer, just as it is on a regular mirror. It wouldn't exactly be rocket surgery to try both ways and see which looks best ;-)

[Silas (son of Silas)]

Like I said in my OP it would have been great to see pictures of the interior of Space Invaders so I could see for myself...

If you have the patience (this is one long page with lots of photos) have a look here for the deluxe version.

Thanks for that link cosam, that site has some really interesting resto pics.

[jukingeo]

Sorry, it's not my cab, just something I came across on the web. Maybe you can find some contact details on the site somewhere. 

Oh, that's OK.  The pictures were actually more helpful when I got to look at them a 2nd time.   I almost spend 45 mins studying the pictures last night and about 90% of my questions have been answered.

I don't think there's any reason it'd have to be 45 degrees. All you need to do is make sure the monitor is reflected somewhere in the field of view of the player. If I were building it, I'd either make a mock-up and experiment, or make the end product adjustable (at least the angle of the mirror, if not the monitor too).

Yes, it does matter that the angle of the mirror to the monitor is 45 degrees otherwise the image would be distorted.  A 45 degree angle would preserve the reflected distances.   Looking at a picture of the inside of one of the side panels does show this as I can clearly see where the mirror and monitor mounts are.   Thus in short, I am seeing a cross section of the mountings.  That is a HUGE help.    Now, it does look like it is still a weird angle, but even though the monitor to mirror is critical that it is 45 degrees, what isn't critical is how the mirror is angled to player.  So more then likely, Midway figured out what the optimal angle was to aim the video to the player and then just maintained the 45 degree lower angle to the monitor.  In addition this would pitch the bottom corner of the monitor down, so it is less likely to be seen by the player (it is put out of the player's field of vision).   So my gathering that as long as the monitor to mirror angle is in the SAME PLANE at 45 degrees, you could rotate that plane in any direction that is desired.   So right there that did answer one big question.

It does also mean that I probably have to make the cabinet slightly larger than originally calculated to compensate for the rear downward angle of the monitor.

I'm no expert on the subject, but I'd have thought the silvered side would be away from the viewer, just as it is on a regular mirror. It wouldn't exactly be rocket surgery to try both ways and see which looks best ;-)

That is what I initially thought as well, but lately I am beginning to think otherwise.   I have a one way mirror at work...the boss' window actually.  I was playing around with it.   If both rooms are lit on each side of the mirror, I cannot look into my boss' office, but he can look out into the main room.   Likewise if I shut the lights off in his office.   BUT I made a strange discovery that if I shut off the lights in the main room and leave the lights on in my boss' office, YOU CAN see in from the otherwise reflected side.  It does look like you are looking through a tinted window, but you CAN see in.

As it stands, the backdrop in Space Invaders IS lit from a light.  So that would mean the other side of the mirror must be as dark as possible.   Have you ever wondered why Space Invaders has that HUGE bezel, but a small window to look in?  Well, the bezel is preventing as much outside light from entering the cabinet as possible.

The monitor just is projecting a few areas of light on to the mirror, so it isn't enough to drown out the back image. 

Thus my guess is that if the mirror was turned the other way around as I initially thought, the monitor display wouldn't be as clear and moreover a reflection of the light would be casted on the backdrop.   So now I am thinking that the silvered side is facing forward.

Granted, as you put it, that is the rocket science approach and it would be simpler just to try the two way mirror each way.

Now, moving on to the next thing...the backdrop itself.  Again looking carefully at the pictures I can see that there is a florescent light bulb in between the half round moon and the back of the cabinet.   The person restoring the cabinet does show the backdrop, but not how it is mounted in the cabinet.  I am assuming that the backdrop is mounted on the rear door of the cabinet and as such the light illuminates the backdrop.   The half round "moon" must be a translucent material to allow the light to shine through lighting it up while masking the light from the viewer.   If that is the case then ANOTHER question crops up.  What KIND of florescent light is that?  It looks like a standard white bulb...but could it be a blacklight bulb?

Geo

[Kevin Mullins]

Blacklight - probably a blacklight "blue" bulb. (more intense UV, less "bright" than the white bulbs)

You're gonna make me go out and get my spare AD mirror and play with it now. 
My complete AD is buried in storage, so I can't just go look at it.
I'm wanting to say the "mirrored" side is facing the artwork.
You'll know it's backwards because you will get a double image from the monitor, which I would think would be a reflection from the "mirror" and a second reflection from the glass itself. (theoretically speaking of course)

[jukingeo]

Blacklight - probably a blacklight "blue" bulb. (more intense UV, less "bright" than the white bulbs)

You're gonna make me go out and get my spare AD mirror and play with it now. 
My complete AD is buried in storage, so I can't just go look at it.
I'm wanting to say the "mirrored" side is facing the artwork.
You'll know it's backwards because you will get a double image from the monitor, which I would think would be a reflection from the "mirror" and a second reflection from the glass itself. (theoretically speaking of course)

Ahhh yes, I have thought of that too (actually read it somewhere) that you have to use a mirror with the silvered side on the outside or the side where the monitor is to avoid the double image.  So that is another reason I am thinking the reflective side is on the monitor side.  BUT, I could be wrong.

Edit:

Well, as it turns out everything just discussed could be all wrong.   I came across this via an unrelated link on this site:

(Scroll out to 1:52)



Apparently there is such a thing called a HALF-Silvered mirror, in which you can see equally through both sides and it is also very reflective.  So I am beginning to think this is the animal we are looking for.

So Kevin, if you don't mind I would appreciate it VERY much if you get a chance to take a look at that mirror.  More then likely in a well lit room if you can see through both sides...then it is a half-silvered mirror and not a two way.

This is becoming VERY interesting!

2nd Edit:

Even some more interesting reading that supports my room lighting experiment with my boss' mirror:

http://www.howstuffworks.com/question421.htm

Geo

[Bender]

Blacklight - probably a blacklight "blue" bulb. (more intense UV, less "bright" than the white bulbs)

You're gonna make me go out and get my spare AD mirror and play with it now.  
My complete AD is buried in storage, so I can't just go look at it.
I'm wanting to say the "mirrored" side is facing the artwork.
You'll know it's backwards because you will get a double image from the monitor, which I would think would be a reflection from the "mirror" and a second reflection from the glass itself. (theoretically speaking of course)

Ahhh yes, I have thought of that too (actually read it somewhere) that you have to use a mirror with the silvered side on the outside or the side where the monitor is to avoid the double image.  So that is another reason I am thinking the reflective side is on the monitor side.  BUT, I could be wrong.

Geo

I think Kevin mentioned the half-silver in the third post

Yeah, I think that's right your looking through to the artwork, in other words it's not reflected in the mirror at all, so there's no chance of a double image, where the monitor is what is reflected so the silver should be facing it to avoid the double image from the thickness of the glass

[jukingeo]

I think Kevin mentioned the half-silver in the third post

Yeah, you are right...he did.   I guess I didn't pay it any mind because it was a term I was not familiar with.  I am more used to one-way or two-way mirror.   But after seeing the video and that fellow mentioned it too, it did get me thinking that unlike the mirrors used in games like Pac Man and Galaga, which is a true mirror, the mirror used in Space Invaders seems like a very reflective piece of glass and that is exactly what a half silvered mirror is.

Yeah, I think that's right your looking through to the artwork, in other words it's not reflected in the mirror at all, so there's no chance of a double image, where the monitor is what is reflected so the silver should be facing it to avoid the double image from the thickness of the glass

There has been much talk about that in other threads about making sure that if a mirror is broken in a reflection cabinet, that the replacement mirror has the silvering process done on the outside.

Geo