Special effects, or so-called VFX

For many years, special effects, or so-called VFX (visual effects), have been used in cinema films and TV series, as well as in television commercials. This is a rather complex term, describing a number of different techniques designed to add to a camera-recorded image, elements that do not exist in reality, or would be difficult to show in the traditional way. These can include fictional creatures, such as dragons or dinosaurs, which were “last seen” some 65 million years ago. Sometimes elements are added to the recorded image that would be costly to realize “live.” Many such objects are first generated in a computer and then combined with the image captured with the camera. What the computer generates is called CGI, or Computer Generated Image.

The key step in combining the CGI image with the camera image is camera solving, also referred to in simpler terms as tracing. Solving loosely translated means “working out” the camera image.

Tracking itself involves tracing image elements in 2D space. This allows you to track the movement of the camera and add relatively simple elements to the image. An example of this is a shot from the film No Second Chances, in which the caption has a ship in the background was replaced in the shot. In this case, it was enough to trace the camera movement and then “hook up” the masking element and the target caption.

Camera solving, unlike tracing, recreates the entire 3D space captured by the camera, so that the CGI elements fit into the recorded image and appear to be “blended” into the frame. In simpler terms, the idea is to give the viewer the impression that what the computer generated was really in the scene they are watching on the TV. Here we have full information about objects in space, in all 3 dimensions, so that the person responsible for 3D graphics is able to easily match CGI elements to the footage.

An excellent example here is a shot from the film Good Greed, where we see the Szczecin Solidarity Square from a bird’s eye view. The premise was that a demonstration of a large group of people was to take place in the square. The film’s script called for about 4,000 people in the square. Organizing such a crowd would be an extremely difficult task to realize in real conditions. Hiring extras, props, medical security, closing the square for the duration of filming shots, involving the police… in short, a logistical nightmare and huge costs. Therefore, the filmmakers decided to shoot an empty square and add the crowd in post-production.

To do this, it was necessary, as a first step, to solvate the shot from a drone, in order to recreate the 3D space. Solidarity Square has a rather unusual shape, as it is not flat. Its periphery rises above ground zero to a height of at least 3 meters, as there is a museum under the square. If the camera solving was done incorrectly, the people added in post-production could be “underground” in the footage, which would look unnatural and unprofessional.

empty square

After determining the 3D space points and camera movement from the drone, we recreated the entire area and inserted the generated crowd of people.

crowd

Then it was time for image post-production, i.e. coloring, adding camera flash, police lights, reflections in the asphalt, etc. Below you can see the final result of our work:

Tracking and camera solving are a very important part of composing a video image with 2D and 3D elements. This is actually a whole separate profession, which requires a good understanding of the 3D environment but also a lot of knowledge and experience in the subject of photography and optics. Incompetently executed tracking can give a completely opposite effect to the intended one, spoiling even the most beautiful shot and 3D graphics.