# Crane Tutorial

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Crane Part 1 | Crane Part 2 | Crane Part 3

Stepping up in difficulty level from the Train section of the tutorial, Rich now begins the process of rigging the Crane. As is his method of working, he begins by organizing the model layers and then planning out the necessary controllers using his Rig Sketch technique. Over the courseof the three parts, Rich creates an interface to easily control the complex motions of the boom arm, the cables and the bucket itself. Once finished it is a work of (rigging) art to behold.

Users can jump ahead to a specific section by using the Chapter selection widget on the right side of the player or by directly clicking any of the Chapter Title links below.

Tab | Time | Chapter | Description
1 | 00:00:14 | Model Prep | Preparing the raw geometry for rigging.
2 | 00:05:54 | Rig Planning | Planning out the rig for the Boom arm.
3 | 00:15:49 | Locators & Setup | Adding the necessary locators to the scene.
4 | 00:38:16 | User Channels | Adding the User Channels and hooking up the modifiers.
5 | 00:59:45 | Scene Prototype | Making the Assembly Group for the cable wheels.
6 | 01:23:07 | Arm Assembly | Connecting the controls to the boom arm locators.
| 01:29:06 | Total Video Time |

Frequently Asked Questions--

Q.) Why didn't he cover breaking apart all the geometry for the Crane like he did for the Train?

> A.) The Tutorials are designed to build on the lesson before it, so that the training can be focused on new concepts and problems to solve. If you REALLY want to see geometry being separated a piece at a time check out the Locomotive section.

Q.) He used the term "Control Structure" what did he mean by that?

> A.) That is just what he is calling the root hierarchy of the rig - Controls, Geometry and Rig. It's just a way to help organize the rig in a useful way. You will want to build your rigs this way to follow along with the Tutorials but feel free to come up with your own organization system for any rigs you do on your own. Just have SOME system to help make your scenes manageable.

Q.) Man he really can't draw curved arrows, dude needs to take a class or something.

> A.) Tell me about it!

Q.) What does he mean by "World Space" movement when he says we can't use the revolve modifier?

> A.) The revolve modifier give you an easy way to make wheel roll properly through a scene. Its rotation is based on the target items "World" position and rotation. This means that even if it has a local value of 0 but its parent moves, it will take the real world amount that it moved and not just its movement relative to its parent. Check out the Modifiers section in the Foundation for more info.

Q.) What?! We have to learn math formulas?!

> A.) Yes, there are times that to be an effective rigger you will need to understand some basic math. It's fine though, we don't get into anything too deep... just finding the circumference of a circle... promise :)

Q.) What does he mean by "Primary" locators?

> A.) There are just the locators that are used to represent the main parts in the model that need to be rigged. It's what we are calling the "Frame" elements that we attach the geometry to.

Q.) He selects something in the 3D view and then can jump right to it in the Item List, how?

> A.) By using the "f" key with your mouse if over the 'Item' List. modo then finds the item you have selected... its really... wait for it... Handy :)

Q.) He hides the geometry with a key command, how can I do that?

> A.) If you hit the "o" key with the mouse over the 3D view you will get display options. In the "Visibility" tab there is an option called "Show Meshes" toggling that on and off will display or hide mesh items. He then went into the History tab in the Command History panel, found the show meshes command, and right clicked on it to assign it to a key. Customizing this is covered in the Preferences Foundation section.

Q.) When he mentions a "Cycle" or "Circle" as being a problem with using modifiers, what does that mean?

> A.) If you have two items and they both depend on each other in some way, lets say Item A needs to get Item B's position before it can set its own. If you try and get Item B to depend on Item A's position modo would complain about there being a "Dependency Loop". How can you get the value of Item A's position if it is connected to Item B's position and in turn, Item A is depending on Item B's position. This is a very clear example, others might be more subtle but still require that you take steps to prevent the "cycle", "circle" or "dependency loop".

Q.) He used the "+" on the left of the Assembly Group to add a new input, can't you just add a user channel directly to the Assembly Group Item?

> A.) No. If you you don't use the UI in the Assembly Group view you can't tag the channel as either an "Input" or "Output". You can add user channels for other purposes but I don't recommend it. modo is a bit twitchy about how it handles these channels with assembly groups so I would just stick to using the "+" buttons for now.

Q.) He's adding in modifiers from within the Assembly Group view, but I'm not seeing them in the Item list anywhere, why?

> A.) When using the "Add Modifier" button in the schematic modifiers will get added under the main scene item, but it won't be attached to any item. All modifiers get added to the scene and the ones you see in the item list are really just pointers to the main listing. To see this click on the little arrow next to the scene name, you will see ALL the modifiers in the scene. You can drag them out of that main listing and parent them under an item if you want. Then when you select it you will see it highlight in both places. For more info check out the Modifiers section in the Foundation.

Q.) He added in channels to "cheat" the values coming out of the Assembly Group, if you get the proper real world values why would you want to adjust them?

> A.) Remember that we are creating elements for 3D animation, not for the real world, so we want to create systems that look good, not that necessarily work right. In a lot of cases what is "accurate" will look wrong because its not what people expect or is not aesthetically pleasing. So in this case having the ability to tweak the output values lets you tune the "Look" of the rig to match the visual goal.

Q.) I tried reordering the output channels in the channel list for the assembly group and now my assembly is not working right, why?

> A.) This is a known bug, internally modo is linking to the channel order NOT the name, so when you reorder them the wrong channels will get connections. Until this is sorted just don't try and reorder either the input and output channels. Sorry about that peeps!

Q.) You would think that after as many hours of recordings that he has done, his jokes would get better, why haven't they?

> A.) Wha?! You don't like his awesome jokes? Tears of infinite sadness QQ ;)

Q.) He just clicked on one of the nodes channel inputs and the connected node appeared, how did he do that?

> A.) If you middle mouse click on a channel input or output that has a connection the connected node will get loaded into the schematic. For more info check out the Schematic section in the Foundation.

Resources--

Links to the modo in-line help system
Docs: Item List (Mesh Layers)
Docs: Cut, Copy and Paste Geometry
Docs: Revolve Modifier
Docs: Assembly Groups
Docs: Locator Display options
Docs: Local Action Center
Docs: User Channels
Docs: Command History Panel
Docs: Measure Distance
Docs: Math Modifiers
Docs: Schematic View

Links to other pages in this training
Training: Pivots and Centers
Training: Modifiers
Training: Assembly Groups
Training: Locator Mesh Display
Training: Align Set Drop Tools
Training: Action Centers
Training: Channels
Training: Modifiers
Training: Assembly and Rig UI
Training: Schematic
Training: Transform Items

File--

Links to the modo scenes used in the video
(click to open in modo)
File: Crane_01_Organize_01.lxo
File: Crane_01_Organize_02.lxo
File: Crane_03_Rig_01.lxo
File: Crane_03_Rig_02.lxo
File: Crane_03_Rig_03.lxo
File: Crane_04_RigPrototype_01.lxo
File: Crane_04_RigPrototype_02.lxo
File: Crane_05_Rig_04.lxo

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