With Kdenlive we can simulate the clean cut of a limb, giving the illusion that one of our actors arm has been amputated. By adding the movement of the arm and the fake splashes of blood we can obtain a realistic result.
In a combat scene it is essential to demonstrate the effects of the action on the characters. Of course, maybe it is not necessary to show the details like in a Quentin Tarantino film, but if we are filming a duel with swords it is inevitable that sooner or later someone will see a part of their body amputated. For example, a leg or an arm. The problem is that we can’t really cut our arm off: there is a good chance they wouldn’t agree. However, we can take advantage of digital editing to make parts of the actor’s body disappear and give the illusion that he has been deprived of an arm. Of course, simply hiding the arm would not help much: viewers need to guess what is happening to believe in makeup. We will therefore have to show the moment of the cut. And we can do it by taking advantage of Kdenlive. All we need to shoot are three clips: a first clip containing only the background, or our scene without the actor. A clip is then needed in which the actor pretends the amputation of the arm. For example, he may first keep his arm flexed, so that it is clearly seen that he has an arm still attached to his body. Then she can quickly stretch it out, and suddenly keep her arm fully stretched out as if she had been amputated (for example, screaming in pain might be quite an appropriate action). To make it easier for us, it is better that the actor does not move his arm too much, or we will have to follow his movement during editing. The third clip must always be shot in the same conditions: the camera and the actor in the same positions as the previous clip, with the same lighting, but the actor must keep his arm stretched out in front of a green cloth (or any other color that stands out well from that of the actor’s arm). In fact, we will delete all of this clip except the actor’s arm thanks to the chroma key, an effect that allows us to eliminate the green sheet by selecting its color and therefore remain with the arm “clean” from the background. We will use this last clip to make the actor’s arm superimposed on the image of the actor without an arm (this is produced trivially by superimposing a part of the background clip on the clip in which the actor pretends the amputation, thanks to the Rotoscoping effect ). Taking advantage of the transitions of Kdenlive we will be able to move the arm giving the illusion that it has detached itself from the body and that it falls on the ground or flies out of the frame. One may ask: why do we use the chroma key when it would be enough to take a photo on the arm and delete the background with a photo editing program like GIMP? The fact is that by using a chroma key movie it is possible to move the arm even while it flies away. For example, to give a comic tone to the scene, the actor can be asked to raise his thumb while holding his arm in front of the cloth: in this way, the spectators will have the illusion that after the amputation of the arm, while it is flying in front of the camera, still have the strength to raise your thumb as if to say “all right”. Or, you can also simply pretend some spasm of the arm, giving more realism to the scene. Again to add realism to the scene, we can insert a splash of blood at the moment of cutting. After all, even if we don’t want to fall into the splatter, nobody would believe in an amputation without blood loss. As always, you can see the example video at the following address: https://www.youtube.com/watch?v=rUQ7EWJePBs
Green towels and green coveralls
To selectively disappear some parts of the body, it is possible to obtain a suit of the same color as the cloth used for the chroma key (typically green). The actor can then put on the suit leaving only the areas of the body that must be visible, for example the head and the back, to give the illusion that he is without legs. In a nutshell, if the actor wears socks and trousers of the same color as the chroma key, we can easily make his legs disappear. In the same way, if the actor wears green gloves, his hands can be digitally removed from the scene, as if they had been cut off cleanly.
A web search
We recover photographs of blood splatters to be used for our effect
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We operate the cut
We digitally cut the actor’s arm
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Here comes the blood
To add realism, let’s make a splash of blood and spots appear
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The arm flies out of frame
We use the chroma key to add the arm that detaches from the rest of the body
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