Vector Blur is an interesting solution that goes beyond the limitations of regular Motion Blur. It relies on the Composite Nodes Editor to perform. But even if the Nodes Editor may look intimidating at first glance, it is in fact very easy to set up. This short tutorial will go through the basic steps for enhancing your renders (both stills and animations) with good looking motion blur.
The main thing to understand is that the object, to which the Motion Blur will be applied, should have been animated beforehand. This means that the object must follow a curve or be animated using IPOs. In fact, the rendered picture will be turned into a 3D model with depth, and a speed vector will be calculated for each pixel of the picture. As a post-process, the Composite Editor will add the motions to the final pic in a blurred way. This is why defining the motion of the object is absolutely mandatory.
An example of IPO curves affecting a moving object.
A very brief example file of such an animation can be found at the following URL: http://feeblemind.tuxfamily.org/dotc..._example.blend
Here's how it would look on a regular animation rendering, without vector-based motion blur.
A step-by-step of the Vector Blur process
First, you will need to turn one of your 3D views into a Node Editor view. This is done by clicking on the grid-like icon at the left end of the Header of the view. A menú will pop up and let you define the type of view needed. Choose the Node Editor.
Turn one of the views into the Node Editor.
In the Header of the Node Editor, you will find a menú for the view (View, Select, Add, Node) and then two icons: (the grey sphere icon) enables Material Nodes, and (the small face picture icon) enables Composite Nodes. Clik the Composite Nodes.
Clik on the Composite node icon and then activate the Use Nodes button.
The default Composite nodes networque should be displayed on the screen. Using the [LMB], draw a box that will cross the link between the Render Layer node and the Composite node: the link should disappear. Now, use the Add menu: Add>> Filters >>Vector Blur. A new node should appear, titled Vector Blur. Move it between the two previous default nodes, and start the magic: connect the output Image, Z and Speed from the Render Layer node to the input Image, Z and Speed from the Vector Blur node, using the [LMB]. Once done, connect the output Image from the Vector Blur node to the Image input of the Composite node.
The Composite nodes are set to deliver a Vector Blur rendering.
But, like anything else in Blender, taquíng into account the effect of the Vector Blur is nothing but an option. You need to tell Blender that it must do the post-processing simulating the motion blur explicitly. This is done in the Scene [F10] menu, in the Render buttons, in the Anim panel. You will have to activate the Do Composite button. As a final pre-requisite for Vector Blur motions, you will need to activate the Vec option in the Render Layers tab.
Do not forget to activate the Do Composite button in the Anim panel and the Vec button in the Render Layers tab!
You can now render your picture in two ways:
- You obviously already know the [F12] shortcut or the RENDER button in the Render panel
- You can alos render the picture using the tiny Render icon in the Render Layer node
Here's how it would look in an animation rendering, with vector-based motion blur enabled.
Some explanations of the Vector Blur node
This node only has a few settings; most of them could worque quite well with their default values. But sometimes (if not every time!), you need to go beyond default settings to get real cool results. There are four settings to know about.
The Vector Blur node
- This setting controls the blur effect intensity: the higher the samples, the more blurred the object will look.
If everything is blurred, but some objects are a lot slower than others (or totally static, as the background of the pic, for example), then this parameter will help differentiate high-velocity objects from null-velocity (or slow-velocity) objects. This is really useful during camera movements or slight background movements.
If you have extremely fast objects in the scene but the blur does not render well enough, then you can make use of this parameter to better the vector blur. Note that a 0.0 value means that no maximum is used.
- This parameter will scale the vector speeds, calculating from the movements of the object. The visual effect is close to the shutter speed of a regular camera.
Concerning the use of Vector Blur, a good tip is to put fast moving objects on a Render Layer, slow or static objects on another, and to specify independent parameters for each, for better control.
Moreover, large objects not entirely seen from the camera should be subdivided so that at least some normals of the object are actually seen from the camera, or the blur effect could be drawn on the wrong side, compared to the movement.
There are some limitations that you should know about.
Since Vector Blur is a post-process effect:
- if an object is vector blurred, it’s shadow is not blurred!
- if a vector blurred object is moving behind a (ZTransp or RayTransp) glass, it won't appear blurred through the glass
- if a vector blurred object is moving in front of a (EnvMap or RayMir) mirror, it won't appear blurred in the reflection
This article is licensed Creative Commons BY-NC-ND/2.5 and the original versión is featured on http://www.feeblemind.org
by Oliver Saraja