Referencing is a major part of a studio pipeline. Knowing how it works and ways to make it work better are essential to a professional workflow.
10
Referencing
UP UNTIL THIS POINT, WE'VE BEEN USING scene files that have all of the rigs imported into the shot. The reason we've done that is to make sure that you are focusing solely on the cheat at hand, and not trying to overcome any technical hurdles unrelated to the chapter.
Now, we're going to dive right into referencing, and hopefully we'll be able to use referenced scene files from now on without leaving any readers behind. Our referencing cheats will make your animation a lot more efficient (at the very least) and possibly save your entire project. It's time to take advantage of the power of referencing!
Referencing Basics
REFERENCING HAS BEEN A PART OF MAYA for many versions, and even before the system was perfected, artists and technicians realized the value of re-using assets in multiple scenes. The concept is simple: instead of having unique copies of frequently used assets in every single scene, create links instead to the source files. This way, changes to the original file will propagate down to the multiple scene files, and you will save immensely on scene overhead and file size. It is not uncommon for an animation file with dozens of referenced rigs (all between 20–50MB) to still be only 1–2MB or so when finished.
1 Instead of importing characters and sets into a scene, we're going to reference from now on. In an imported scene, the data from all of the imported scenes combines to create a lot of scene overhead. In the referenced scene, the only data that is saved is changes to attributes, like animation curves for instance. The result is a far slimmer scene with less overhead, smaller file size, and the ability to make changes to assets and have those changes propagate into all of your referenced scenes.
2 Open blank_Scene.ma. Go to File > Create Reference 
. In the options box scroll down and make sure Shared Nodes and Display Layers are both checked. Click Reference.
3 Choose ball_Rig.ma in the file dialogue that appears. Maya will load the file as a reference and bring you back to your panel. It looks like it's imported but let's take a closer look. Open the Outliner/Persp panel layout by clicking its icon in the toolbox.
4 See the blue diamond next to the ball_Rig:all group? That means the node is referenced. You can see all of the reference nodes by right clicking in the Outliner and checking the Show Reference Nodes box.
5 Go to File > Reference Editor. This box will give you control over adding, substituting, and removing references from your scene. It is also where you might go to troubleshoot a reference.
blank_Scene.ma
blank_Scene_finish.ma
You can change the namespace in the Reference Editor, which is recommended if your filename is very long – shorten the namespace to something more manageable.
6 Close the Reference Editor, and select the ball rig's ball_Anim control. Set some random keyframes, moving the ball around the scene between frames 1 and 24.
7 Open the Reference Editor. Uncheck the box of the reference node. This unloads the reference, so the ball disappears. The reference is still there, it's just temporarily not in the scene. Check the box again and play back your animation.
8 Notice that the squash and stretch attribute is animated. This animation is in the rig file itself. Up until now, you were unable to make any changes to animation curves on referenced objects. Now you can! In Window > Settings / Preferences > Preferences, under the Animation tab, check “Allow Referenced Animation Curves to be Edited”.
9 blank_Scene.ma has a display layer called env_GEO. Our rig file has the same layer, and so objects in the referenced file are loaded into this layer when you check Display Layers in the reference options. Turn the visibility of this layer on and see.
10 Let's replace this reference with a ball with a different color. Go to File > Reference Editor, select the rig, and click File > Replace Reference. Choose ball_Rig_Yellow.ma. Since the naming and hierarchy is the same, the animation stays intact.
11 In the Reference Editor, click the Duplicate Reference button. This is handy if you want to populate a scene with multiple references of the same file, but as you'll notice, animation isn't copied because it is considered an “edit” done in this scene.
12 Notice how the display layers are still shared even when you duplicate a reference. You want to make sure your reference settings are correct before you duplicate anything. In the Reference Editor, select this new reference and remove it by hitting the Remove Reference button.
Come up with a standardized naming convention for your display layers and you'll find that you can get away with having as few as four or five that will allow you to handle hiding and showing all the objects in your scene!
Offline Edits
THE REFERENCE PIPELINE IS DESIGNED to give artists the ability to manage a massive number of scenes, first and foremost. Most of the functionality built into referencing is geared towards this goal. Even the tool we're going to use now, Export to Offline File, is geared towards being able to make edits to multiple scenes. We're going to cheat by using it as yet another way to export animation.
Reference edits come in all shapes in sizes, literally. Modifying an object's components, changing a texture's color, scaling the rig, even setting a keyframe is considered an edit. By allowing animators to export reference edits to an offline file, Maya 2013 has actually created a new, robust, and rock solid way to export animation. In fact, this new method is by FAR the most full-featured and fool proof method to export animation in Maya now.
Why? Exporting animation via AnimExport, Copy keys, even the brand new AtomExport only exports channels that have keys on them. Since changing ANYTHING is considered a reference edit, this offline file you export from the Reference Editor contains all attributes that have changed in your scene, even if there are no keyframes on it. I can't tell you how many times I've tried to import animation from an animator's scene only to discover they did not put any keyframes on the master control. I then have to go into the animation file, put a keyframe on all controllers (even unchanging ones) to be fully sure I am importing the entire performance. Not any more. In fact, this offline file will even recreate nodes that are related to the changes to your reference file, meaning constraints, layers, EVERYTHING.
1 Open ref_Offline_start.ma. You will recognize this file, as we just made it! Select the ballAnim control and notice there are no keyframes on the rotation channels. In Rotation X, Y, and Z, put values of 1, 2, and 3, respectively.
2 Now we're going to get fancy. Go to Create > Locator. Hit F2 to get to the Animation menu set. Select locator1, 
select the ballAnim control, and go to Constrain> Orient . Make sure just X is checked, and hit Add. We want to see if exporting the edits includes these new nodes.
3 Let's also add the locator and the ball rig to a new render layer. In the Outliner select locator1 and ball_Rig:all group. In the Layer Editor's Render tab, click the New Layer from Selected button. Name this layer “testLayer”.
4 Now we export the reference edits.. Open the Reference Editor, select the ball rig reference, and go to File > Export to Offline File… . In the export dialogue go to Edit > Reset Settings. Hit Export to Offline File, and name it “ball_anim. editMA”.
ref_Offline_start.ma
ref_Offline_finish.ma
We added a locator that controls a channel in our referenced file using an orient constraint. If the direction was reversed (the referenced file controlling an object in the scene) then exporting the reference edits would NOT include the locator.
5 Remember we're hoping that not only the animation was exported, but the relating nodes like render layers, the locator, and the parent constraint. Create a new scene, and hit 
+
to load a reference. Choose ball_Rig_Yellow.ma.
6 Now select the ball_rig_Yellow reference in the Reference Editor, and go to File > Assign Offline File . Change the setting Apply via from Reference to Import. We don't want to load another reference of the edits themselves, we want the animation and nodes imported into this scene. Hit Assign Offline File and choose ball_anim.editMA.
7 Check it out! First play back the animation and you'll see the animation has transferred. Also notice the locator1 has been brought into the scene as well. Select the ballAnim control. The constraint is in place, and the values of 2 and 3 in Y and Z rotation have come through too, even though there are no keyframes on those channels.
8 Select the render layer testLayer. See how the locator1 and the ball rig are loaded into this render layer? Excellent. Absolutely every single reference edit, modified attribute, animation curve, even render layer has been exported and imported perfectly. This tool may have been intended to propagate changes to many files, but we're going to cheat and use it to copy animation from now on!
This tool is super-powerful at exporting information. Be careful, it exports ALL reference edits. If you mess up a material accidentally, for instance, that edit will be in there too, unless you remove the reference edit using the List Reference Edits menu in the Reference Editor.
Saving Reference Edits
WE'RE IN THE HOME STRETCH of a project, and a change needs to be made to a referenced asset. But maybe the fix needs to be done in an animation scene and not the referenced file itself.
What kind of change would that be? Any problem that only presents itself in an animated scene, like a weighting issue, a rig issue, a material change, etc. It could be quite possible that we'd only see this kind of problem as we animate our character. The normal workflow would be to note the change you want to make, save and close the file, open up the referenced file, try to recreate the problem, make the change, save the file, open up the animation scene, see if the change you made in the referenced file actually solves the problem, and repeat as necessary.
Yikes. Using the Save Reference Edits command we can fix problems much more efficiently.
1 Open edits_Start.ma. The reference file is not found. No big deal. Navigate to the Chapter 10 folder and find Moom.ma. Check both Make path changes permanent and Remember these settings.
2 Now that Moom is in the scene, we're going to select his controls and make sure the rig is working correctly. Select his right upper arm FK control.
3 Rotate it down against his body.
4 Yikes. He clearly has some weighting issues. Let's work these out and save the edits back into the rig file. Hide the display layer named displayBody and show the layer named skinnedBody. This geometry is the one we'll do the weight painting on.
edits_Start.ma
We normally check weighting in as many poses as possible when skinning. A great way to check if your weights are good is to use a modular rig system and to load animation onto your rig in the rig file itself. This saves being surprised later on.
5 Select the body geometry and in the Animation menu set (F2), go to Skin > Edit Smooth Skin > Paint Skin Weights Tool.
6 In the Tool Settings panel, select the influence named moom:jWristR. You will know it's the right one if the wrist AND the body turn grey to show there is influence on it. Change your paint tool to Scale and the value to 0.
7 Paint the zero weight on the body to remove the wrist's influence. Once all of the influence is removed from the body, select the upper arm control and rotate it around to check and see. If you see body vertices moving, repeat steps 5–7.
8 Turn off the display layer skinnedBody and turn the displayBody back on. Open the Reference Editor. Right click on the Moom reference and choose File > Save Reference Edits. It will inform you that you cannot undo this change. Choose Save.
9 Let's test it! Open up Moom.ma in this chapter's scene folder. Grab his arm control and move it all around – the skin weights are now working correctly!
You have to make sure you are not sharing any layers when you load your references, if you want to be able to save reference edits. A good idea might be to load references without anything shared to begin with, then switch to shared layers when you are sure you are finished making edits.
Giving Feedback
by Kenny Roy
IN THE LAST EDITION OF HOW TO CHEAT IN MAYA there was an interlude about getting feedback. Feedback is an essential part of the animation process. Indeed, we are creating experiences that are not meant to exist in a vacuum, they are meant to be enjoyed by audiences! To summarize the last edition's interlude, feedback is how you know you are improving not only your animation skills but your appeal and storytelling sensibilities.
But getting a feedback is only half the picture. You have to GIVE feedback as well. In short, while very helpful to the animator receiving your comments, giving feedback is actually a VERY self-serving gesture. Let's talk about why.
When you first started in animation, doubtless you were driven by performance and a zest for awesome motion. You quickly found out, however, that the incredible animation you saw in your head was years away from emerging from your fingertips. Animation takes a lot of time and effort to learn. But you persevered! You found resources like this book and you are taking learning animation with Maya very seriously. You get feedback on your work constantly, and always strive to incorporate the best suggestions in a way that will fit nicely into your established workflow.
What's missing?
It has been often said that you only retain 10% of what you hear, 25% of what you see demonstrated, 75% of what you practice, and 90% of what you teach. To put it simply, the best way to really solidify a concept is to teach that concept to someone else. In doing so, you are simplifying the concept in a way that YOU understand. This is different from memorizing a concept explained in SOMEONE ELSE'S way. Rather than just remembering a word-for-word regurgitation of an idea, you internalize the idea for simple explanation to others.
So is giving feedback on other people's animation really the same as teaching? Absolutely. You are first watching the animation to spot anything that doesn't appeal to your ever-improving eye. Once you've picked out a part of the animation that needs improvement, you must dive into the animation “vault” in your head and start retrieving the concepts that will allow you to voice your opinion clearly and thoroughly. Repetition of this process can mean the difference between knowing a concept, and really understanding a concept.
There is YET ANOTHER benefit to giving feedback that occurs after you have done it for a while. I'm often asked by my students for tricks on how to keep a critical eye your own animation. They are right to ask: the ability to be self-critical deep into the progress of a shot can be almost lifesaving in crunch time. Well, besides the normal tricks, like watching your animation in a mirror, playing the animation backwards, taking a break, etc., giving lots of feedback carries a nice side effect. After you've critiqued hundreds and thousands of pieces of animation you can easily switch into “critique mode”–a state of mind where you can actually look at your own animation as if it is someone else's, and as if you are seeing it for the first time. This ability doesn't come until after you've given feedback on at least a thousand shots. While that may seem like a LOT of animation, there's nothing stopping you from getting started today!
So go right now to an online forum and start being selfish: give feedback like there's no tomorrow! Here are some of my favorites if you need suggestions on where to start: