Wednesday, September 30, 2009

2.5 Camera Controls

The purpose of this video is to demonstrate the camera controls in Blender 2.5. The controls are similar to Blender 2.4x. 2.5, at least my pre-alpha release as of mid-September, adds some interesting controls, notably the Panorama lens, simulating a 360 degree fisheye lens. You could follow along with a 2.4x Blender version, although you would need to either create your own version of Quad View or just follow me with your own 3D view.

The camera settings are grouped in the Object Data icon for the camera object. In 2.4x, highlight the camera (right click), and press F9 for the Edit buttons. Since the controls are very similar, if you know your way around the Blender 2.4x camera, you should be able to become comfortable with Blender 2.5's camera very quickly. I don't think you can buy a camera with all of Blender's features. You can get some interesting effects by adjusting its controls, which might be easier than moving the camera.

We'll start with the 2.5 default scene, and highlight the camera. This demo works best in the new Quad View. From the View Menu, select Toggle Quad View to see the scene from Top, Front, Right, and Camera views simultaneously.

Look at the Camera View, in the upper right corner of the 3D viewport. The camera is in Perspective mode and the cube is in the center. Press F12 to render.

The camera controls are located in the Object Data area of the Properties Window (formerly known as the Buttons Window). By default, Blender renders the camera in perspective view, where parallel lines meet at a vanishing point. The lens angle defaults to 35 millimeters, a standard camera lens. Increasing the angle causes the camera to zoom into the cube. Decreasing the angle causes the camera to zoom out. You can choose degrees instead of millimeters, if you wish. Here's the scene rendered from a 100 degree camera lens.

Press the Orthographic button. The camera now is in Orthographic view, where parallel lines do not meet. Below the Perspective / Orthographic buttons is the Orthographic Scale area, set to 7.314. If you lower the scale setting, it's as if the camera zooms into the cube. If you raise the scale setting, it's as if the camera zooms out and the cube is farther away from the camera. This is a way of changing the camera's view without actually moving the camera.

Check the Panorama check box and press F12 to render. The result is a cube as if it was shot with a 360 degree panoramic fisheye type lens.

Turn off the Panorama check box and switch back to Perspective view.

Go to the Display area and check the Limits button. Limits gives each view a line showing how far, in blender units, the camera sees. You can control what the camera sees by changing the Clipping Start and Clipping End parameters. Clipping Start, defaulting to .1, is the number of blender units where the camera starts to see. Clippiing End, defaulting to 100, is the number of blender units up to where the camera sees. Change Clipping End to 5 and press F12 to render. The cube does not render because the camera's view is clipped before it sees the cube. You can see that the camera's clipping end is before it sees the cube. Increase Clipping End until the camera can see part of the cube, at 10 blender units or so. Then press F12 to render. Incidentally, the camera view shows how much, if any, of the cube, will render. Now the a part of the cube is rendered. Press Z to go to wireframe mode, so we can see the inside of the cube. Increase the camera's Clipping End to 11 and press F12 to render. We see even more of the cube. Finally, with clipping end at 12, the camera can see the entire cube.

The Passepartout checkbox, which is on by default, is a visual way of showing what part of the scene the camera sees. In 2.4x, Passsepartout is off by default. Uncheck the Passepartout checkbox. The entire camera area is shaded uniformly, so you would not know what the camera see unless you render the scene.

Check the Passpepartout check box. The alpha slider underneath Passepartout controls the transparency (alpha of 0, means fully transparent, alpha of 1 means fully opaque) of the passepartout area - how much of the scene under it is shown.

Check the Title Safe button, which is off in 2.5 but on in 2.4x. Title Safe is a dashed line which shows the limits of the area that would display on certain television screens. Don't worry about it unless you are planning to distribute your video to television. Even here, Title Safe only applies to certain types of televisions. Uncheck the Title Safe button to show what will render. Move the cube to the upper left corner of the Passepartout area and press F12 to render. The cube actually renders in that area.

Highlight the camera and go back to the camera controls settings.

The Shift X and Shift Y settings allow you to adjust the camera viewing area without moving the camera, similar to you adjusting a real camera.

Check the Name button. This shows the camera name - Camera - in the 3D viewport.

Size is size of the icon, defaulting to .5 blender units used for the camera icon. It has no effect on the rendering. You may want a bigger or smaller camera icon in your scene. Note the filled in triangle at the top of the camera. The fact that the triangle is filled in means that this camera is the active camera, the one that will be used when the scene is rendered.

Although you can have as many cameras as you like, only one active camera is allowed in Blender. To illustrate, select the camera and press Shift-D to duplicate. Then move the new camera to another part of the scene. The new camera has a hollow triangle instead of a filled in triangle, which means that it is not the active camera. In Blender 2.4x, you could make the new camera the active camera by pressing Control-Alt-Num0. My pre-alpha version of Blender does not have this functionality yet. You need at least one camera to render a scene. In Blender 2.4x you would get the "Error-No Camera" message if you did not have a camera and pressed F12. In Blender 2.5, no error message is produced, but you don't get a render either.

The Mist check box shows the mist area for the camera, if Mist is on. To illustrate, I'll move the cube back towards the center of the scene. Then, we go to the World buttons, turn on the Mist check box there to enable mist. Set the start of the effect at 1 and the end at 11. Press F12 to render. Part of the cube is shown, the other part is shrouded in mist.

Depth of field can be set for an object, or in blender units. It determines where the focus of the camera is. Depth of Field can be set in blender units, or you can specify an object on which the camera will focus. We'll set Depth of Field to the Cube object. DOF won't affect the render unless we use nodes, with the Defocus Filter or a blurring type of filter. We'll save that discussion for another time.

That's it. The Blender 2.5 camera can produce interesting effects to make your scenes more realistic.