Natron

Natron is a node-based compositor.

To use Natron at its fullest potential, you should have OpenColorIO and OpenCV (both available from http://slackbuilds.org installed. These are not strictly necessary, so if you just looking at Natron, it will still launch, but for actual work you probably want these technologies installed and active.

To a budding or working comp artist, even Natron's install will be familiar. Download Natron and run the executable. It runs an install “wizard” prompting you for an install location and offering an automatic download of various optional components.

The install can happen in two different ways:

• Run the installer as a normal user and install to a location in your home directory (for instance, ~/bin/natron)
• Run the installer from a terminal using the kdesu command and install to a systemwide location, (such as /opt)

Compositing is both a science and an art, but the user mechanics of Natron don't take long to pick up. There are not many tutorials online on the subject, but there are plenty of online tutorials on similar products, and the information and demo assets are surprisingly compatible.

The term “composite” literally means “something made up of disparate parts”. In the context of visual effects, this refers to anything from overlaying text on top of video to taking a 3d-modeled troll and placing it next to a campfire that was shot in the real world. Both tasks require at least taking two separate images, dropping garbage that is not needed in a frame, combining the two images, and integrating them.

To begin with, practise making download the Slackermedia logo from the front page of http://slackermedia.info and save it to your hard drive in a sensible location. The full path to the image is http://slackermedia.info/images/bigskull.png

$ wget http://slackermedia.info/images/bigskull.png

Launch Natron from the K Menu or from a terminal.

The Natron workspace.

• The top left of the Natron window is a viewer.
• The bottom left is the Node Graph (called a “script panel” by most compers).
• The right half of the Natron window is the Properties panel.

In the Project Settings panel in the Properties area, set the colorspace if that is important to you (for this demo, it is not). Set the Frame Range from its current default value of 1 - 1 to 1 - 24. Set the Frame Rate to 12 or so (only because this is a demo and full specs are not required).

To import a movie or image sequence or, in this case, a single image, into Natron, right-click any where in the Node Graph area and select Image → Read, or just press the r key on your keyboard whilst your mouse cursor is with the bounds of the Node Graph.

Once the image is in your workspace, it may not show up in the viewer (depending on how you imported it) because it is not connected to the viewer. Click on the arrow head on the bottom edge of the Read image node and drag your mouse cursor over to the Viewer1 node. After you release the mouse button, an arrow appears between the nodes, and the image appears in your viewer window.

Natron sets your viewer size to the size of the first image you import. In the Project Settings panel in the Properties area, set the Output Format to a reasonable demo frame size. Since this is just a demo, a small frame size might be better, so set it to PAL unless you want to stress-test your computer to see what it can handle.

In Natron, nearly everything is a node. If you are experienced with GIMP or Synfig, then whatever your impulse might be to do in either of those applications can be translated to finding a node in Natron to do the same job. It's not always a direct translation, but it's a good place to start.

With the Slackermedia logo in your workspace, add some text:

• Right-click in the Node Graph window.
• Select Draw → TuttleText.
• In the Text field of the Tuttle Text properties panel, type a string. Set the font size and font to something you can easily see.
• Set Colour to white and Background Colour to black.

If you connect the TuttleText node to the Viewer1 node, the text takes over the viewer and it's all you see. You lose the logo, even though both are being fed to the viewer.

That's where the compositing comes in; to see two layers together, you must composite them together:

Right-click in the Node Graph window. Select Merge → Merge. Connect the image node to the A input of the merge node. Connect the text node to the B input of the merge node. Connect the merge node to the viewer.

If the viewer does not update properly, turn on Turbo Mode by clicking the rightmost button in the Timeline strip between the viewer window and Node Graph. This requires more RAM but if you have it, use it. If all else fails, disconnect the viewer and then re-connect it (more commonly known as “unplug it, and plug it back in again”).

Turn turbo mode for faster viewer updates.

The two images are now composited together. The default merge is an over composite. There are several different types of compositing, and sometimes they go by slightly different names in different programmes, but the principles are always the same.

Change the merge composite type in the Merge1 properties panel.

Natron would be an over-complex version of GIMP were it not for the fact that it composites pictures that move. Since most of the pictures in Natron will be moving, it's not unusual for the elements you are using to composite them together to have to move.

Currently, the Slackermedia logo and the text in the demo composite are static. Anything that has a keyframe button next to it can be animated, and there are several additional nodes that add more animate-able properties to your assets.

To animate something in Natron, use keyframes. The keyframe buttons are located in the Property Panels.]:

• Make sure the playhead is at frame 1 by using the play controls along the timeline.
• In the TuttleText property panel, click the keyframe button and select Set Key (All Dimensions. This creates a new keyframe; in the timeline, the playhead turns blue.
• Move the project playhead to frame 16 (or some frame later in time), and click the keyframe button again to set a new keyframe.
• You have two keyframes, but no motion between the two points in time. The easiest way to tween in Natron is the Curve Editor window, which is a tab behind the Node Graph window. If there is no Curve Editor tab, click the Layout button to the left of the Node Graph tab and select Curve editor here.
• Switch to the Curve Editor window and locate the lines that represent the X and Y positions. As in Blender, use the mouse wheel (or the scroll function1 on your touchpad) to zoom in and out. Middle-mouse click to move around in the Curve Editor.
• Grab onto the keyframe markers in the Curve Editor to change the values of the TuttleText node in whatever way you want your animation to occur. For instance, try moving the text from right to left.

The curve editor makes keyframing easy and familiar to any Blender user.

When you're finished your animation, send the playhead back to the start and press play.