How to light indoors so that no shadows can be seen on the white background behind the characters?

Find a white wall, white cotton cloth or photographic cloth, and brighten the whole background with strong lights to make it overexposed. First of all, we must determine whether the light source is outdoor natural light or indoor artificial light, as well as the direction, color temperature and intensity of the light, so that our illusionist can better cooperate with the photographer to arrange the characters in the light area as much as possible. Generally speaking, the outdoor light is strong. It is one of the most common lighting methods for documentary lighting to make use of these powerful natural light and the artificial light brought by ourselves. "Mix and match" is reflected in the difference between cold light and warm light on the screen. Generally, there are fewer people who shoot documentaries, and they rarely bring too many lighting equipment when they go out to shoot. Moreover, there are many low-color lamps with 3200K red heads in China. At this time, it is essential to prepare enough blue paper. Its purpose is to raise the color temperature from 3200K to 5600 K. Only in this way can we ensure the consistency of color temperature and the accuracy of shooting people's colors. In the process of shooting people, hit people in the face with a 3200K low color temperature lamp? The color temperature of the background is still outdoor light. At that time, the facial light of the character may be normal, but the background light is blue. The biggest possibility is that the lighting equipment of the film crew is too small to balance the color temperature of the background, so it is ok to give the characters a face light. But it's not advisable to run out like this, which is very dangerous, because we can't see the real color change. If the ambient light overwhelms the artificial light, the human face may appear blue, because the ambient light will definitely interfere with the facial light of the person and produce mixed light. Mixed light means that the color is uncertain and the natural person's skin color is inaccurate. If the color temperature of 3200K is determined according to the human face, the light with the color temperature of 5600K coming from the outdoor will cause all objects in the background to appear blue, including some parts of the characters. This blue color is flat on the screen, red or not, green or not, yellow or not.