Object Properties
Projection
In this menu the perspective of the camera can be changed. For a normal camera perspective, select Perspective. The perspectives Fisheye, Spherical, Cylindrical and Stereo Spherical simulate very wide-angle lenses or even perspectives that cannot be captured with real cameras. These perspectives can be useful for creating panoramic renderings or VR environments, for example. Here you can find more information about these perspectives:
Fisheye
Fisheye lenses can capture ultra-wide-angle images that are circularly distorted. In some cases, the distortion can be aesthetically desirable.
The left side shows an example scene with a camera surrounded by spherical objects. Rendering this scene with a fisheye camera and a viewing angle of 180° produces the result shown on the right.
This angle defines the area to be captured in front of the camera. For example, an angle of 180° results in the entire area that lies in front of the camera (along the positive Z axis of the camera) being seen in the rendering. This can also lead to empty areas being visible in the corners of the rendering. In these cases, you can use the Scale values to zoom into the rendering.
These values can be used to scale the rendering along the width and heights to create a zoom effect. For Scale values greater than 1, the rendering zooms along the corresponding direction, which means that areas lying at the edge are no longer visible in the rendering.
Spherical
A spherical camera can capture a 360-degree panorama. The produced images are called 'latitude-longitude' images (often abbreviated as 'latlong') and can be used as environment maps or as a dome light texture.
The spherical camera has no options of its own. The main camera's FOV is ignored but its aspect ratio is used to allow for fine-tuning the effect, if necessary. A spherical camera always captures an image with 360 degrees of horizontal FOV and 180 degrees of vertical FOV. For this reason, it is recommended that the rendered image size has a 2:1 aspect ratio. The recommended camera aspect ratio is 1.0. To demonstrate the effect of the spherical camera, we'll use the following reference scene. The camera is pointing towards the green sphere. The red sphere is 90 degrees to the left of the camera and the blue sphere is 90 degrees to the right. The black sphere is exactly behind the camera.
Example rendering of a Spherical Camera using the same setup as schown in the Fisheye camera example above.
Cylindrical
The Cylindrical camera is similar to the Spherical camera except it can capture a user-defined horizontal and vertical FOV range. When using a Cylindrical camera, the main camera's FOV is ignored but its aspect ratio can be used to fine-tune the effect.
The Cylindrical camera has its own horizontal and vertical FOV settings (Angle of View for X and Angle of View Y). Furthermore, it can optionally use an orthographic projection for the vertical axis. In that case, the vertical angle is replaced by an orthographic Height. The function of this orthographic Height is the same as with a regular orthographic camera.
To demonstrate the effect of the cylindrical camera, we'll use the same reference scene, as presented above for the Fisheye camera. The camera is pointing towards the green sphere. The red sphere is 90 degrees to the left of the camera and the blue sphere is 90 degrees to the right. The black sphere is exactly behind the camera.
The left side shows an example scene with a camera surrounded by spherical objects. Rendering this scene with a Cylindrical camera and an Angle of View X of 180° produces the result shown on the right.
This activates an orthographic perspective for the representation of the perpendicular direction. This eliminates the Angle of View Y parameter and replaces it with an absolute Height value.
This is used to specify the camera's opening angle in the X and Y directions. When using the Orthographic option, the Angle of View Y value is omitted and replaced by an absolute Height value.
If Orthographic is active, the vertical aperture angle of the camera is indirectly defined by this length specification.
The Stereo Spherical camera is primarily useful for Virtual Reality (VR) applications. It can render stereoscopic panoramas in various different modes.
The Mode setting determines the image layout:
- means that the Left and Right eyes are going to be placed horizontally next to each other.
- means the images will be placed on top of each other (Left on top, Right below).
- only renders the view of the left eye.
- only renders the view of the right eye.
By default, the stereo spherical 'eyes' look straight ahead. By activating this option, the Focus Distance setting from the Optical tab allows the eyes to slightly rotate and focus at a particular distance from the camera's position.
This value determines the distance between the left and right eye. The Separation value is in scene units so it depends on your scene's representation of a unit (meters, centimeters, inches, etc). A typical distance between the eyes of a mature human would be about 6.5 cm (about 2.56 inches)
This sets the Angle of View for the horizontal and vertical directions. To receive an undistored rendering, the aspect ratios should also be adjusted alongside the Angle of View values. For example, if we used a 180 degree horizontal and vertical FOV (i.e. the "front hemisphere"), the aspect ratios should be 2:1 for the Side by Side Mode, 1:2 for the Top Bottom Mode and and 1:1 for the Modes Left and Right.
Standard Perspectives
The following perspectives, such as Right, Front or Top represent the standard viewing directions and perspectives of the 3D viewports
When switching to Orthographic perspective, the camera uses a parallel perspective, comparable to the standard viewport viewing directions. The difference is that the camera can still be freely placed and rotated in space.
The Isometric perspectiven is offering a fixed camera perspective and results in equally foreshortened axis directions with an angle of 120 degree between any pair of axes.
Finally the Dimetric perspective also offers a fixed viewing direction, but the camera can still be moved. Parallel edges remain visually parallel and the lengths along the X and Y directions remain proportional. Only the distances along the Z axis appear shortened.
All Orthographic, Isometric and Dimetric perspectives offer a Zoom value to control the visual size of the objects
Lunghezza Focale (mm)[1.00..10000.00]
In a real camera, the focal length represents the distance between the lens and the sensor. Small focal length values are used for wide-angle shots and present a wider view of the scene, but also distort the image (especially very short focal lengths). Larger focal length values zoom into the given scene accordingly. The greater the value, the less distorted the image will be until the perspective effect is lost completely with extremely large focal length values and the parallel projection effect increases.
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Influence of the focal length on the perspective and the representation of the objects |
The Focal Length is directly linked to the Angle of View in the formula illustrated below and works for the horizontal (X) and vertical (Y) direction. Larger Focal Length values produce a smaller field of view and vice versa.
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The field of view represents the camera's horizontal and vertical angle, respectively, to the scene. The field of view is directly linked to the focal length. The greater the focal length, the smaller the field of view and vice versa. A small field of view represents a camera with a telephoto lens; since only a small portion of the scene to be photographed enters the camera, this portion naturally appears very large on the light-sensitive surface of the camera, resulting in a zoomed-in image. Incidentally, Field of View changes if the proportion between Width and Height are modified in the Render Settings.
Suppose the Redshift camera worked like a traditional, analog film camera, with images being recorded onto photographic film one after the other. Now imagine if additional image information could be recorded by moving this film along the X and Y axis. This is exactly what these parameters do. Redshift takes this one step further in that it does not restrict itself to the size of the filmstrip.
This can be very useful as it lets you move the rendered objects without changing their perspective. Objects that might have been placed too close to the border of the rendered frame can be visually moved more towards the center of the image. Another application is the correction of vertical lines in architectural renderings. In such cases, rotate the camera so that the scene horizon passes exactly through the center of the image (P-rotation = 0°). By using the Shift Y component, you then shift the horizon back to the desired height in the image. The vertical lines are preserved because there is no third vanishing point above or below the horizon.
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On the left side, the camera is tilted slightly upward to mimic the view of a pedestrian. This results in an often undesirable skewing of the vertical lines in architectural renderings. On the right side, the camera has a P-rotation of 0° and uses only the Shift-Y component to move the building down in the image. The vertical lines now remain undistorted. |
The Zoom value can only be defined if a parallel perspective (this includes orthographic views) is used. This setting then defines the scaling of the view. The default value of 1 will always cover an area of 1024 units on the horizontal axis.
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On the left a Zoom of 1 covers a viewing area of 1024 units along the X-axis of the camera. On the right, if you double the Zoom to 2, the horizontal viewing area is halved . |
Sensor
The sensor of a camera is usually a fixed element that evaluates the incident light. In conjunction with the focal length, the size of the sensor determines, among other things, the field of view of the camera.
The aspect ratio of the sensor can be set freely, but does not necessarily affect the aspect ratio of the rendering. This is defined exclusively by the render resolution that you set in the Render Settings.
If you like to reuse different Sensor Size settings, the Preset menu offers commands to add or delete presets for them.
In this menu you can manage various presets for the sensor size. The currently set sensor size can be saved here with an individual name using the Add Preset menu item and thus accessed again at any time. Entries that are no longer required can also be deleted from the list by selecting Delete Preset.
Here you set the size of the sensor in X and Y direction. If you want to keep the existing aspect ratio when resizing, activate the Lock Ratio option.
Both values are not necessarily required. The following Fit menu controls how the Sensor Size is to be evaluated.
If you like to reuse different Size settings, the Preset menu offers commands to add or delete presets for them.
Activate this option if you like to keep the ratio of the sensor size during editing.
Here you select the dimension of the sensor which, in conjunction with the selected render resolution and Focal Length, define the Angle of View (X/Y) on the camera.
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- Horizontal: Only the X-Size of the Sensor Size is used
- Vertical: Only the Y-Size of the Sensor is used
- Overscan-Fit: Always the smaller sensor length compared to the Film Aspect from the Render Settings is evaluated. If a Film Aspect of 4:3 is rendered and the sensor size is 40 * 29 mm, the 29 mm sensor height is used as the basis for calculating the angle of view. If the sensor size is 39 * 30 mm, the width of the sensor would be evaluated instead in this example.
- Square: This mode is using the default 36 mm * 27 mm Sensor Size used in full frame photographic cameras. In case your render resolution is not using a 4:3 aspect ratio, only the x component of the Sensor Size is used for the Angle of View calculation.
Clipping
Use the Near Clip Plane and Far Clip Plane options to specify two distances (Depth values) measured from the camera position. Only geometry between these distances is evaluated for display and rendering.
This setting defines cutting planes that lie perpendicular to the angle of view of the camera. The Near Clip Plane will remove all geometry that is closer to the camera than Depth. The Far Clip Plane will ignore all geometry that is further away from the camera than defined by its Depth value. Note, however, that these objects will remain closed for the renderer with most effects. Shadow casting light sources cannot illuminate the interior of such cut objects. When applying Far Clipping, the Background can be used to avoid rendering objects that lie in cut off regions at the rear of the scene black by default.
Use the Depth values to define the distances from the camera to the given cut plane. In the Display tab of the camera object, you can also find the options for Near Clip Plane and Far Clip Plane, to draw additional frames for these distances in the viewport.
The top row shows the original scene on the left. The image next to it shows the effect of a Near Clip Plane, cutting off the forground part of the landscape object. The image on the top right additionally uses a Far Clip Plane, cutting away all of the walls in the background and the back half of the landscape.