3D in Depth: Cameras | 2 | WebReference

3D in Depth: Cameras | 2

3D in Depth: Cameras

In 3D software a typical sampling of available stock lenses could be 15mm, 20mm, 24mm, 28mm, 35mm, 50mm, 85mm, 135mm, 200mm. All of these preset values are the camera’s focal length in millimeters. Of course, you’re not tied to these presets. You can adjust the Focal Length and Field of View to meet your needs.

Another important setting is the aperture. In a physical camera, this controls the amount of light entering your camera. It’s also used to control the depth of field. In combination with the focus plane, depth of field blurs objects in front of, or behind the camera, using f/stop settings. In 3D, depth of field is an optional effect that you would have to enable, unlike in real life. In 3D, you have precise control over the depth of field, but changing that setting will not directly affect the amount of light in your scene. That is controlled by adjusting light intensities, but that is the subject of another article.

In this image, all the pyramids are in focus, the result of a wide depth of field.

In this second image, the depth of field has been set so that the closest pyramid is in focus, while the ones in the middle and far distance are blurred.

In this image the depth of field has been set so that the pyramid in the middle distance is in focus while the pyramids at the near and far distances are blurred.

3D Camera Types

In 3D applications, you’ll encounter two or three different types of cameras. As an example, in 3D Studio Max, there are two types of cameras, Target and Free. A Target camera views the area around and object. The Target camera is represented by an icon of a camera and the target as in this image. Both can be animated. If you’re not moving the camera on a path, the Target camera is your preferred choice.

With a Free camera, the view is the area where the camera is aimed. In this case, the icon is only of the camera and its Field of View. The Free camera works well when the camera position is animated along a path. An example of usages include: banking or tilting, such as architectural walkthroughs or roller coaster rides. In general, it’s best to use a Free camera when the camera is to move within the scene and to use a target camera when the camera position is fixed.

Zoom, Dolly, Truck, Orbit, Pan

Zooming and Dollying are related, but there is an important difference between the two.

Dollying is where you physically move the camera, but the focal length stays the same.

In contrast, Zooming is where you change the camera’s Field of View.

Truck refers to moving a camera parallel to the image plane. If you’re using a Target camera that would mean moving both the camera and its Target parallel to the Camera view.

Orbit refers to moving the camera around a target.

Panning is where the Target would rotate around the Target Camera. If you’re using a Free camera, you would rotate the camera around its local axes.

Created: June 5, 2003
Revised: January 8, 2004

URL: http://webreference.com/3d/column8