You have two eyes so that you can sense 'depth' when you look around you. Each eye sees a slightly different image and your brain can analyze the differences to estimate how far away things are. With a 3D program like Blender we can produce pairs of images to give your eyes the same impression of depth when your eyes sees the pair of images, but what is the best way to ensure that each eye sees the correct image? Several solutions are possible and are explained on a page that you can access via THIS LINK. One solution, the theme of this page, is to create a combined image called an anaglyph in which one of the original images is present only in red and the other is present only in cyan (blue and green). If the viewer wears special glasses with a red filter over the left eye and a cyan filter over the right eye then the left eye will see only the red image and the right eye will see only the cyan image. So don't bother reading any more of this page unless you can obtain the necessary pair of (very cheap) glasses, like this (from Amazon, Ebay etc):
A nice addon is available for free download which, once installed in Blender, makes it rather easy to generate your own anaglyph images. Here is an example of an anaglyph made with the addon (yes, it's time to put your red-cyan glasses on):
This below is the same image without the 3D effect:
This is the 3D viewport view which shows the three planes. Note that the three monkey heads are almost completely between the near and far planes.
The three planes do not show up in the final rendered view (F12) but they are visible in the 'live-rendered' view:
Here is the procedure for installing and activating the addon (this is not necessary at school for it has already been done)
- Download the addon from www.noeol.de/s3d/
- Start Blender or reload the default file it to ensure that you have the default setup for we will be modifying the default file to ensure that the addon remains installed
- Do open File>User Preferences>Addons>Install Addon. Install the addon and activate it.
- Do File>Save Default file
Here is the procedure for using the addon that have installed as above
- Select the camera
- Set the properties window to display the 'Object Data' context
- In the 'stereoscopic camera' section, turn on Auto set of Near and Far plane and click the Set Stereo camera button.
- Move your objects around and/or adjust the Zero Parallax value until all the objects that will appear in the render are between the two outer planes (Near and Far) which define the limits of comfortable viewing. Note that objects on the middle plane (the zero parallax plane) will appear to be on the screen (neither in front of it nor behind it) in the final image. If the near and middle planes are in the way you can hide them by selecting them and pressing the H key. To unhide press Alt+H. Note that you can move objects now but not after the next step (not without making your life difficult, at least). Note that the three planes are there just to help you place things - they will not appear in the final render. This is because of settings in the Outliner panel, in the 'camera' section.
- When you are sure you do not need to change anything any more, Press the button 'Create L and R scenes'. This does just what it says- it creates two new scenes. In one of these scenes the left camera is active and in the other the right camera is active. These scenes are used in the final compositing process.
- Switch the 3D viewport into a Node Editor window
- Switch to Compositing Nodes and activate Use Nodes
- Delete the two existing nodes
- Open the properties panel (N) and the stereoscopic presets
- Choose the red-cyan anaglyph preset
- Click Add Nodes. Try to understand how the nodes work. One branch takes the image from the left camera and filters out the blue and green components, allowing only red to pass through. The other branch takes the image from the right camera and filters out the red component, allowing only blue and green to pass through (the combination of green and blue makes cyan).
- Turn the Node Editor back to the 3D viewport
- Press F12 and wait...
Lastly, note that anaglyphs can be used to made 3D movies, not just still images. See the excellent 10 minute anaglyph movie 'Pangea, the never-ending world' on YouTube, for example.