Shadow Generator in Green Screen Wizard


GreenScreenWizard offers three shadow generators.

  • The Wall Shadow Generator
  • The Floor Shadow Generator
  • The Wall and Floor Shadow Generator


  • To activate any of the generators, simply decide on the type of generator you would like and click on the appropriate button at the bottom of the screen.

    The Wall Shadow Generator

    The wall shadowed generator gives, as the name implies, the ability to produce shadows on a wall. The wall shadow generator is the simplest to use and understand. It simply takes the green screen image and wherever there is something solid it creates a black spot projected onto the wall. You can move and scale the shadow using the top three controls shown.



    You also have control as to how blurry and how dark the shadow will be.
    Here's the shadow with blur increased:



    Here's the shadow with more transparency:



    If your shadow has unwanted spots or if the hair or dark areas are not showing up you may need to adjust the restore black slider. This slider, like the slider in the combined page, will determine which blacks are solid and which blacks are transparent. To remove the shadow simply uncheck the "Add Shadow" checkbox or hit the "Clear" button.

    The Floor Shadow Generator

    The floor shadow generator is designed to place shadows on the ground or floor. It is more complicated because people who are standing on the ground want the shadow to start where their feet touch the ground. Because GreenScreenWizard does not know where the person is standing you, the user, must tell it.

    Notice in this image, Carolyn seems to be floating above her shadow. That is because the skew base, represented by the red line is not aligned with her feet. We use the skew base slider to align the red line with her feet, causing the shadow to be properly aligned.



    Here is the image with the skew base in its proper position. Notice how the shadow is now properly positioned now with her feet.



    You can remove the red line by clicking "Clear Guides" or by unchecking the "Show Baseline" checkbox.



    Once you have the base defined, you can skew the shadow to the left or the right using the skew slider.



    You can also scale the shadow using the scale slider.



    A problem arises if the feet in the photo are not parallel to the base of the photo.
    Consider this image:



    As you can see we cannot move the baseline so that both feet have the shadow at the right level. We can solve this problem in one of two ways. We could move the feet off the screen as shown here. In this case we have moved the shadow base below the bottom of screen.



    A more complicated way to solve the problem is to use the base angle. You adjust the skew base in the base angle until both feet are touched by line. For bizarre mathematical reasons which I won't get into you need to manually move the shadow into the proper position using the right-and-left and up-and-down controls.



    As with the wall shadow generator, you can use the shadow transparency and shadow border controls. In addition to those feature, you may also want to use the show virtual room function to make a more constant background for shadow adjustment.

    The Wall and Floor Shadow Generator

    The shadow generator that creates an image on the floor and the wall is the most complicated. It will attempt to do a skewed image on the ground until it hits the edge of the wall and then it will create a shadow on the wall for the remainder of the image. To create this effect we need to give the shadow generator two pieces of information. Like the floor shadow we need to define the skew base to tell the shadow generator where the shadow should start. In addition we need to define a virtual room to tell the shadow generator where the floor ends the wall starts. This is probably best shown by example.

    Let's start with this image. As you can see there is some floor and some wall, in this case curtains.



    Clicking the wall and floor button will cause the following image will appear.



    The red line is the skew base that needs to be lowered to below her feet. The light gray area shown is the wall of the virtual room. The dark gray area is the floor. We can adjust this dividing line with the virtual room left edge and the virtual room right edge sliders. In this case we need to lower the virtual room slightly tilted to match the curtains.

    After we adjust the virtual room to match the line of the curtains we can adjust the scale and the skew in the skew base to give us a realistic shadow.



    We then click the "Clear Guides" button to remove the virtual room and if present, the skew baseline.



    Closing the dialog will cause the Wizard to compute the final output as shown here.



    The shadow generator only works on things that are visible on the screen. It also assumes a flat background, one that does not have any holes like a window.

    If used properly the shadow generator can add realism to your green screen photography.