Front Projection

Front Projection

The concept of Front projection is very simple and quite similar to a chroma-key effect. However, instead of applying an image where a color screen is, it replaces the selected surface(s) with a selected image.

In most cases, the image you select for a Front Projection Map is the same image you use for the Background Image on Layout’s Compositing Tab of the Effects Panel (Windows > Compositing Options).

Scale, Position, and so on, are not relevant with Front projection. It is always the size (and frame/pixel aspect) it would be if loaded as a Background Image. As such, changing the Resolution or Pixel Aspect Ratio on the Camera Properties Panel will also affect the Front projection.Front projection is used primarily for comp (compositing) work where you combine LightWave objects with a live-action background image or sequence. A common example occurs when you want a LightWave object to cast a shadow (believably) onto the image or behind a portion of the background image.

The image used in the surface and the background will pin-register the surface to the background, letting you go in front or behind. Your object then appears to interact with the environment. You can cast shadows or cause reflections from a regular 3D object onto the surface that is front projection mapped.

Front-Projection mapped Ground surface catches the character’s shadow.

The ground object is just a flat box with Front Projection Image Mapping that uses the same image as the background. Its job is merely to catch the object’s shadow.

Another example is to use an image of trees as your background image and fly a UFO between them so the UFO appears to go in front of some trees and behind others. All you need to do is model some rough shapes that match the trees you wish to fly behind (they could even be flat planes).

Another good example for Front projection is to create a flat plane and align it to an image of an ocean or a lake. Front projecting the water surface onto it lets you place an object beneath the water and push it through the surface. Submarines and sea creatures will appear to break the surface this way.

The hardest part of Front projection is aligning the objects, matching lighting, and getting the right camera angle. Using Background Image as the Camera View Background on Layout’s Display Options Tab of the Preferences Panel (Edit > Display Options) will allow you to do all that. You also must search for the right balance of Luminosity and Diffuse for the Front projection surface so that the object’s true shape is not revealed by shading.

Fixed Projection

Front projection surfaces will always look the same no matter where you move the object or which way you rotate it. The image does not normally stick to the surface. However, if you activate the Fixed Projection option (previously Sticky Projection), it fixes (i.e., locks) the projection from the camera’s perspective at the specified Time.

The default unit of measure for Time depends on the Frame Slider Label setting on the General Options Tab of the Preferences Panel in Layout or the Time Format setting on the Display Options Panel, Units Tab in Modeler. You may specify the unit of measure by appending f for frames or s for seconds to the entered number (e.g., 22f for frame 22, 31s for 31 seconds). You may also enter SMPTE time code, like 00:00:01:16 for one second, frame 16. The entry is converted to the default unit of measure.

Use Fixed Projection to create parallax with two-dimensional images by using a technique called Camera Mapping. (Use the Reference Camera setting to select the camera, if you have multiple cameras in your scene.)

Essentially, you set the frame where the texture will be pin-registered to the background (like normal Front Projection Mapping). On all other frames, the texture is stretched to compensate for more or less of the texture being visible, which is caused by factors like the camera being moved.For example, in a picture of some buildings, you could place the LightWave camera in the same place as the original camera in relation to some simple 3D buildings; then, you could project the picture onto the buildings and lock it at frame 0. You’ll need a doctored background image/object - with Fixed projection - to reveal what’s behind the buildings. If you move the camera forward, it will appear to fly into or around the buildings.