Cameras
From ShadeCamp
The user interface for the virtual camera in Shade allows it to simulate a real-world camera. Taking photographs in the real world uses a truck running on the ground or on rails, or a tripod fixed to a crane to which a camera is attached by means of a pan head. The camera can be moved vertically and horizontally, and can be inclined or elevated using the handle on the pan head. Perspective compensations and inclination of the focal plane can be realized with a view camera. Using a zoom lens enables you to change perspective easily. Most of these can be simulated with the camera interface in Shade. This chapter explains the principles of an actual camera -- that is, the relationship between the lens and the film. For details on the features of the Camera window, refer to the chapter entitled “Camera Window” in the “Shade Reference.” For the basic operation of cameras, refer to the section “Using the Camera” in Chapter 1 of this User Guide.
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Dollying the Camera
You can simulate the movement of a camera truck or crane running on rails using the Motion window. You can display either a path along which the Eye point moves or a path along which the Target point moves.
Camera objects
Just like objects, you can create, display, and edit multiple cameras in the Figure window, but you cannot render them. When referring to the object characteristics of a camera, we call it a “Camera object.”
Eye point, Target point, and Focal length
The Eye point is the location of the camera or observer within the 3D workspace. The Target point determines the direction the camera faces, and both of these points are always in the Perspective view and the center of the Image window. Comparing this to a physical lens system, the Eye point is equivalent to the rear principal point (second principal point). Focal lengths cannot be confirmed intuitively, but can be understood from the size of the image on the surface of the film—that is, by the Perspective view. Shade enables you to set the focus-related settings using the focus button, focus slider, and focus text box in the lower portion of the Camera window.
Using the Camera
The image viewed in the perspective window directly affects the rendered image. To modify the scene shown in the perspective view, the Camera window is used. You can use the camera in Shade in real time, as if you were looking through the viewfinder of a camera. In this chapter we will use a sample Shade scene to better visualize the changes to the camera settings. Open “UG_11_Table.shd” from the Documentation - Sample tab in ShadeExplorer before continuing.
Displaying the Camera Window
1. Choose View > Camera to display the Camera window.
The basic method for using the Camera window is to select one of the right-side radio buttons (Eye, Target, Eye & Target, and Zoom), and then drag the mouse pointer within the joystick box to control the view.
The perspective view is mainly determined by the settings for the Eye Point (camera position), Target Point (the position on which the camera focuses), and the zoom value. The two points, eye and target, determine which direction the camera faces.
Rotating the Camera
Rotating the camera moves the Eye point, effectively changing the direction, or angle, at which the camera is facing.
1. To check the positions of the Eye and Target Points, click the Zoom Out button in the Toolbox to zoom out the three views.
2. Click the Eye radio button in the Camera window and press point A.
While you hold down the mouse button, you can see the line connecting the Eye Point and Target Point (this line is sometimes called the sight line) in the Figure window, and a camera cube (X axis, Z axis, and horizontal line) displayed within the perspective view. The camera cube is displayed only when the Cube checkbox is selected.
3. Drag the mouse from point A to the right.
According to the direction and distance you drag, the Eye Point rotates counterclockwise around the Target Point. Refer to the sight line and the camera cube to move the Eye Point. When you release the mouse button, a new position is set for the Eye Point. If you drag the mouse to the left, the Eye Point rotates clockwise around the Target Point. As long as you drag the mouse from position A and keep the button pressed, the Eye Point changes continuously. If you release the button, you must move the mouse pointer back to position A before dragging again. If the Eye Point has not moved enough after one operation, release the mouse button and start dragging again from position A.
4. The Eye Point can be moved vertically, horizontally, and diagonally. Check the motion of the Eye Point by dragging the mouse in several directions within the virtual joystick. You can also change the view without using the joystick.
5. Drag the mouse pointer in the perspective view while holding down Space.
With the Eye radio button selected, if you drag the mouse pointer in the perspective view while pressing the space key, you can change the eye position in the same way as you did using the joystick. Dragging the hand pointer in the perspective view is affected by the radio button selected in the Camera window.
6. Click the << button under the joystick of the Camera window to return to the original perspective view.
Clicking the << button allows you to restore the sight line to the previous state. The >> button moves the sight line forward to the next state.
Camera Pan and Tilt
You can pan and tilt the camera by moving the Target point.
1. Click the Target radio button on, place the mouse pointer at position A, then drag it to the place you want to see.
The Target Point moves around the Eye Point according to the direction and distance you drag. When moving the Target Point, the Eye Point does not move, and the Target Point moves such that the length of the sight line is fixed.
2. Click the << button in the Camera window and restore the original settings for the view.
Another method of moving the Target point, regardless of the current Camera mode, is to click and drag in the Perspective view while holding Space + Ctrl (Win) or Space + }{ (Mac).
Camera Crane and Dolly Movement
The movement of a crane or dolly can be simulated in Shade to move the camera vertically or laterally while keeping the relative distance between the subject (the Target point) and the camera (the Eye point) equal. What this means in Shade is that the Eye and Target points will move together in sync.
1. Click the Eye & Target radio button on, place the mouse pointer at position A, then drag it downward.
The Eye Point and the Target Point move downward in parallel according to the direction and distance you drag. Since the camera moves downward, the wireframe shape shown in the perspective view appears to move upward. If you drag the cursor upward, the Eye Point and the Target Point move upward in parallel.
2. Click the << button in the Camera window to restore the previous settings for the view. Another method of moving the Eye and Target points together in sync is to hold Ctrl (Win) or control (Mac) while moving the mouse wheel in the Perspective view.
Dollying the Camera In and Out
Decreasing or increasing the distance between the Eye and Target points makes the subject appear to get closer or farther away, simulating the effect of dollying the camera towards or away from the subject.
1. Click the Zoom radio button on, place the mouse pointer at position A, then drag it up and down.
The Eye Point moves closer to the target according to the distance you drag up, and the shape shown in the perspective view becomes larger. If you drag the cursor downward, the Eye Point moves farther from the Target Point, and the shape shown in the perspective view becomes smaller. In this case, only the Eye Point changes, while the Target Point remains fixed.
Changing the distance between the Eye and Target Points Note: With the Zoom radio button selected, if you press the Ctrl key (Win) / option key (Mac) and simultaneously drag the mouse up or down within the joystick, the Eye Point remains fixed and the Target Point is moved along the sight line connecting the eye and target. The apparent view in the perspective window does not change.
Dollying the camera towards or away from the subject can also be done at any time regardless of the current Camera mode, simply by moving the mouse wheel in the Perspective view.
Zooming the Camera
In addition to moving the camera closer or farther away from the subject, the camera’s focal length can be changed to zoom in or zoom out. 1. Select the Zoom radio button to switch to Zoom camera mode. Click at position A, then drag to the right and left.
The Focal Length
The focal length is changed according to the direction and distance you drag, and the focal length value (9- 720mm) shown in the Camera window is updated as well. The Eye Point and the Target Point do not move. Moving the virtual joystick to the right narrows the angle of view (creating a telephoto effect). Moving the virtual joystick to the left widens the angle of view (creating a wide angle effect).
Zooming the camera lens can also be done regardless of the current Camera mode, by moving the mouse wheel in the Perspective view while holding Shift.
Camera Shortcuts
Many camera operations can be done in Shade by using mouse shortcuts in the Perspective view. Memorizing these shortcuts may make it easier to view your scene from many angles quickly, without needing to switch to the Camera window to use the virtual joystick each time. Each of these shortcut operations is done in the Perspective view of the Figure window.
Pointing the Camera at Objects or the 3D Cursor
To quickly center the current camera on the 3D cursor or the currently-selected object(s) in the scene, use the Set & Link buttons in the Camera window.
Click the Cursor button to the right of Eye to set the Eye point to the current position of the 3D cursor. Click the Cursor button next to Target to set the Target to the 3D cursor. Click the respective Object button to set the Eye point or Target point to the center of the currently selected object. Click the respective Link button move the Eye or Target point to the center of the currently selected object and to link the camera to that point. If you then move the linked object, the camera Eye or Target point will move with it.
1. Click the Target radio button in the Camera window.
2. In the Figure window, click the center of the vase in two of the three views, while holding down Ctrl (Win) or option (Mac).
Clicking in the two views allows you to set the 3D cursor position at the center of the Vase. Shade remembers the 3D cursor position you clicked last. The 3D cursor follows the movement of the mouse pointer in the Figure window. However, when you move the mouse pointer out of the Figure window, the 3D cursor will jump to the position you last clicked. This position is called the “set position” of the 3D cursor. Clicking in the Figure window while pressing Ctrl (Win) or option (Mac) sets the position of the 3D cursor without changing the current selection.
3. Click the Cursor button located to the right of the Target radio button in the Camera window.
The Target point is set to the position of the 3D cursor, changing the camera to point directly at the vase. You’ll notice the vase is now in the center of the Perspective view. Similarly, if you click the Cursor button next to Eye, the Eye Point moves to the 3D cursor, showing the camera view from the vase. Clicking the Cursor button next to Eye & Target sets the Eye point to the 3D cursor position, but moves both the Eye and Target points together.
4. Select the cushion in the Browser.
5. Click the Object button next to Target. This sets the Target point to the center of the cushion.
6. Select the vase again.
7. Click the Link button next to Target. This links the center of the currently selected object (the vase) to the camera’s Target point.
8. Select Translate from the Move tool in the Toolbox, and click and drag in the Figure window to move the vase. The Perspective view changes to keep the vase centered in view, since the camera is set to always point toward the vase.
9. Now click the Unlink button. The object and the Target point are unlinked, and the button changes back to a Link button.
Creating Camera Objects
Shade has two different types of cameras; the camera we have mentioned so far (called the Meta-camera) and a camera objects. The Meta-camera cannot be manipulated as a object, but you can create a camera object. The camera object can be operated on in the Camera window as well as in the Figure window, where you can modify its position and orientation.
Let’s create a camera object.
1. Choose Camera from the Create tool in the Toolbox.
2. While holding down the Ctrl key (Win) / option key (Mac), click the position shown in the figure below in the Front view.
3. In the Top view, click and drag your mouse from A to B.
A camera object is created.
4. Choose Camera from the Camera pull-down menu at the top of the Camera window.
The view in the Perspective view has changed to that seen from the new camera. The Camera pull-down menu toggles the Perspective view between the Meta-camera and the camera object. The name of the camera object shown in the Browser is displayed in the Camera pull-down menu. You can create multiple camera objects.
This figure is shown with all objects selected, after switching to the camera
5. Choose the Eye radio button and move your mouse freely within the virtual joystick box.
The camera object changes direction, according to the motion of the joystick.
You can also modify the view by changing the position or orientation of the camera object directly.
6. Select the camera shape in the Browser, if it is not selected.
7. Choose Translate from the Move tool in the Toolbox. Click and drag from A to B.
The Move Tool
Use the Move tool to move the camera object. You can see the Perspective view changing as the camera object moves. For most work in Shade you probably don’t need the camera objects to be visible. (You can still view your scene from camera objects that are invisible.) To hide the camera object, turn the Volume and Sight checkboxes off in the Camera window.
By now you probably have a good understanding of how cameras work in Shade and how to pan, dolly, track and zoom the cameras in your scene to achieve your desired perspective. Subsequent chapters will not describe in detail the methods of changing the camera views, but refer back to here if you need to refresh your knowledge of working with cameras in Shade. For more technical information on how cameras and lenses work in Shade, see Appendix 1: Cameras and Lenses in the User Guide. For more details on the Camera window, see the Reference manual.
The view after switching back to the Meta-camera
The Focus Button
Click the Focus button to set the focal distance to where the 3D cursor is located.
From left to right: the focal distance is set to the front, center, and back objects.
Simulating Depth of Field
When Path tracing is selected as the rendering method, the focus slider and text box can be used to simulate the effect of depth of field. Drag the slider or enter an appropriate value (other than 0) in the text box to create depth of field in accordance with the focal distance that was set using the Focus button. The bigger the value, the shallower the depth of field, and the larger the out-of-focus blur.
From left: Focus values of 0, 0.5, and 1. |
