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The most fascinating non-CGI effect from Terminator 2 is a cut scene which can be seen in the director's cut, where they use Linda Hamilton twin sister in a surprising way: to fake a "mirror" scene where Sarah is operating on the Terminator's head.

They are in front of a mirror. They wanted to actually use Arnie in the reflection to show his face; they wanted a dummy for the head closest to the camera, to show the surgery inside the head. So they used a window in the wall instead of a mirror! Linda Hamilton and her twin sister are mimicking each other's movements to make it seem it's a mirror image.

(The other use of Linda's twin sister, the scene where the T-1000 fakes being Sarah, is better known)



I agree this is super neat, but for what it's worth, the "the mirror is actually a hole in the set" technique is kind of a standard go-to in movie making.

I am very enamored with the iconic "impossible mirror" shot in Robert Zemeckis' "Contact" instead, which used subtle CGI to brilliant effect to innovate over the practical bag of tricks. It's my single favorite effects shot in movies: https://youtu.be/avRdYf78kLk (from 1:10 for the impatient)


On the topic, another neat video covering several "impossible mirror" shots in movies (including Contact): https://youtu.be/VASwKZAUVSo


Amazing. I do wonder if I'd actually notice just watching it (haven't seen the film) vs. it being pointed out to me though. I think I miss (just thinking 'nice cinematography', but not realising specifically why) a lot of clever stuff.


For what it's worth, i missed it when watching the movie. It just feels like there's something weird that just happened but you can't quite tell, like a nice and subtle spice in a well made dish.


> I do wonder if I'd actually notice just watching it

Almost certainly not; that's the point.


I don't remember whether I noticed it or not when I saw the movie, but I'd like to believe I would have. It reminds be a bit of the final scene of Hitchcock's "Birds":

https://www.youtube.com/watch?v=ULxw4UDY5g8 (up until 0:35)


1. What reminds you of Birds? I don't see the parallels.

2. The original Birds did not have that music. I cannot believe how classic media remasters completely ruin the tone of the originals. From Star Wars, to Rust in Peace, to Birds now.


The parallel is not obvious because no mirror is involved. It is the fact that camera is moving backwards in front of the actors who approach a closed door. Then Rod Taylor reaches for the handle and opens the door and the outside light shines in.

How come the camera is not in the way at that point? Did it move backwards to the closed door? The answer is quite interesting. Let me know if you'd like me to spoiler it for you.


I remember being surprised by the effect, and totally unsure how they pulled it off. Positioning the camera in exactly the right angle to match what the moving camera was shooting? I can't even picture it. Impressive work!


There is another set of twins used, that is the security guard who gets a full house on the coffee machine. He meets his 'double' that is actually the t-1000, who 'pokes' him through the head. The actor duo are in a few other movies, including Gremlins 2, where they aren't trying to fool the audience, but just are twins.



This is also pretty common in video games where a mirror is just a window into another room with a duplicate player model.


It's what they did with Duke Nukem 3D, I know. But in videogames it's not a practical effect, but "CGI" by definition, so it impresses me way less ;)


That's not entirely accurate. DN3D required a large room behind the mirror (I'm saying this from the perspective of editing levels), but that room was completely invisible and did not have to look like the mirrored room at all. The mirror actually "mirrored" the scene. IIRC, if you disable collisions then you could walk through the mirror into that big room, which looked quite boring.

I always assumed that the "big room" was to avoid the culling algorithms / potentially-visible-set tripping over the mirror.


Seems like there should be a computationally less expensive way to do that.


Screen-space reflections are faster and require no new scene draws, but they won't show you "new angles" on reflected objects and they won't go around corners. Planar reflections require a new scene draw, but that's actually pretty modest: non-planar reflections require six scene-draws for a cubemap or full on raytracing.

In general, lots of things in games require re-rendering the scene multiple times per frame, so game engines are really, really good at this. Shadows, projections, transparency / translucency, motion/depth blur, indirect lighting, deferred lighting, even things like hit testing (though for dependency + latency reasons that's a prime candidate for offloading to the CPU). Anything that requires less visual fidelity will have its performance tuned accordingly: fewer pixels, simpler shaders, lower LOD geometry, lower framerates. Nobody will notice if the fuzzy bounce lights are calculated once every five frames and blended.

Ray tracing is conceptually simpler but (so far) slower at any given level of cleverness -- you'll often hear that it has asymptotic benefits, but those same benefits can be pulled out of rasterizers with effort comparable to what is required to make the raytracing practical.

Here is a writeup of the passes you might expect to see in a modern engine: https://zhangdoa.com/posts/rendering-analysis-cyberpunk-2077

Here's an overview of a modern geometry pipeline: https://www.youtube.com/watch?v=eviSykqSUUw


I don't think you could do a mirror with screen-space reflections.


Sure you can, people do it all the time, but I'll grant you that it kinda sucks (which is how I notice that people do it all the time). There are situations where everything you want to reflect is already on screen and the angular difference between the camera and reflected camera isn't enough to be noticeable. When those conditions are met, SSR is awfully tempting. Water is the usual suspect, but wall-mounted mirrors can work too if the camera will only see it from glancing angles and it's reflecting a wide-open space.

Tradeoffs, tradeoffs, everywhere.


In blender eevee render that's famous for screen-space magic you can get realtime mirrors with "reflection plane" "light probe" by placing it over the surface that's supposed to be a mirror.


Look up “instancing” with regards to geometry on GPUs. The mesh can just be rendered twice with different transforms.

That said, it often makes sense to drop some of the decorative flourishes used on the primary instance of the model due to distance, or use a different level of detail. There’s really no great way to get around needing to tell the GPU to render the triangles twice (short of rendering the view to an intermediate buffer and using that, which is still twice…)


La Haine also contains a fairly nice use of the "mirror set extension" trick: https://www.youtube.com/watch?v=okQJPUTQMqA


Interesting! In this case, was it used to avoid showing the camera?


Surely it's intended as a more deliberate (not technical) device - seeing his 'reflection' we're seeing him as he sees himself, his self-image. (I haven't seen the film though.)


Oh, I understand the cinematic effect, what I'm asking is why they used a trick instead of an actual mirror. I suppose because the actual mirror would have shown the camera behind, right?


Even for a momentary shot of a doorknob in ‘The Matrix’, the camera had to be hidden—in the jacket: https://collider.com/wp-content/uploads/2019/05/matrix-doork...


Very cool! I didn't know that. It's amazing all the kinds of shots that are done in movies that one would assume are trivial to accomplish, but that actually require tricks.


You are correct!

Without using this technique you'd have the camera in shot.


I don't think it would work with an actual mirror - either Cassel will block the mirror or the camera will block Cassel.


Somewhat on topic, the impossible flying camera in Soy Cuba: https://www.youtube.com/watch?v=rjuLkJ4m-mc


Cool! I didn't know it was more widespread. I suppose the innovation here is that the actress and her double are twin sisters.


They used that a whole bunch for the mirror scenes in Quantum Leap where Sam would look in the mirror and see himself as whoever he leaped into and there was someone else in the scene. That series was a boon for actors who had identical twins.

The other identical twin thing I remember was an episode of Buffy the Vampire Slayer where Xander was split into two, one of him all his strengths and the other all his weaknesses. Nicholas Brendon's twin brother was used in the scenes where there were two Xanders in one shot.


> (from 1:10 for the impatient)

To the impatient: The meaning of this shot depends on the first 1:09 minutes.


Amen! I remember frame-advancing the LaserDisc over and over to study how they resolved the shot at the end.


Huh? Do you have a reference for that?

This is what I remember from T2 director's cut: https://www.youtube.com/watch?v=yiBHj8Xs4sg (at 0:21).

When I saw the theatrical cut it always confused me how John could tell who was the T1000. And it also annoyed me that Arnie shot the frozen T1000, seemingly only speeding up his thawing.

In the director's cut you see that T1000 is actually damaged, but not damaged like a non-liquid robot would be. It's not losing mobility (control) of an arm, but instead losing control of its morphing functions.

It's complete genius that was (almost[1]) entirely cut from the theatrical cut. It's ridiculous that the edit it out.

[1] There's exactly one "flicker" of T1000 metalliness in the theatrical cut. A small remnant of a genius idea.


> Huh? Do you have a reference for that?

I can't find the "making of" video where they tell how they did this, but here is the cut scene: https://youtu.be/tZNE637BeEI

In scenes where you see Arnie's face in the mirror at the same time as his head being operated on, it's not a mirror, and one of the two Sarah's is not Linda Hamilton (whoever's face is shown less clearly).

Edit: lots of hits on Google saying this is how they did it, but I cannot find a single authoritative reference, like a making of video or someone involved in the production saying so.


Ok, I was being an idiot. I was thinking of the other Hamilton-twin scene.

Got it, yeah that was a good use of her.


Oh i remember as a kid it made sense, they didn't have that kind of relationship. Since his mom was a badass always fighting type, she didn't care about herself she just wanted John to live, but here she was calling him like "John, help me". While the real mom was just "Get out of the way" no BS type. And yeah like the other poster said, if it was T-1000 he wouldn't say get out of the way.


I couldn't agree more about the cutting out of the T1000's erroenous morphing. It adds what, a second and a half to the film? I can't imagine why they felt the need.

I also really like the scene where John tries to teach him to smile, but at least there they have the excuse that it's a minute or two in length.

Certain other scenes, like Kyle's visit and the extra nuclear nightmare scene, I think the movie is better without.


The one cut scene I admit without hesitation ruins the movie (and so they were right to cut it in the theatrical version) is the happy ending where Skynet is defeated.

The actor playing John Connor looks ridiculous. Linda Hamilton in aged makeup looks silly. The whole scene looks corny.

And it defeats the "no future" vibe that worked so well in the first Terminator movie.

"There's a storm coming."


I just figured that T1000 would never say “get out of the way!” instead of just shooting him.


I was too young to see T2 at the cinema and never got the big deal about T2 until I saw the theatrical cut uninterrupted in one sitting. The pacing is incredible, there literally isn’t a wasted minute. It must have been agonizing to cut and rearrange otherwise great material.


"Oh boy!"

The same technique of using an extended set to fake a mirror was frequently used on Quantum Leap.



Airplane! might be the greatest movie of all time. It's funny, but it is also suspenseful, has great acting, and is full of serious subtlety and commentary. Even with the humor removed it is a terrific film.


It was at least the third or fourth watching when I noticed that one. One of the densest movies I've ever encountered.


This is explained in one of the DVD extras on my copy of Terminator 2. I don't remeber if it's in the director's commentary of the movie or one of the extra videos and I don't have time to look it up. But it's definitely there.


From T3 (I believe this was a cut scene too) but really enjoyed the backstory for the T800 chassis and voice https://youtu.be/kayFrIR-Qfw


Ah... the brilliance of the old days.


Why not just use a half silvered mirror, that way you don't need the twin


If you could see the reflection of Linda Hamilton in the mirror, wouldn't you also see the reflection of the Terminator dummy?




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