Lo-Res to Hi-Res

Animation Swaps

by Adam Sale

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Objective: To efficiently animate a low resolution character, and then transfer all of the animation data to a more complex enveloped and weighted character before the final render takes place.

Synopsis: By using two different characters, whose bones are of the exact same configuration, with the same names, we will be able to animate the bone hierarchy of the first low resolution character, save its animation file, and then associate that same animation file to the second high resolution character. ________________________________________________________________________

Preparing your scene

This tutorial assumes that you have already built a complete character that has been properly enveloped and weighted to a skeleton. If not, see the Character Rig tutorial for more information. When you have completed your character, create a database called HI_RES and save your character to that database

 

The second step is to create the low-resolution version of your character. I find that the simplest way to do this is to get primitive objects that approximate the size of each major piece of your character and parent them directly to the bones. With a leg for example, two cylinders do a nice job of approximating the thigh and shin portion. When you have constructed and parented the low-resolution portions of your character, delete the Hi resolution pieces of geometry that you have just replaced. In the example scene shown here, notice how I go from working with a Forty Thousand Polygon character to a Three Thousand Polygon character. Aside from lowering Polygon counts, which allows Softimage to process your animation requests faster, my low-resolution character has no envelope that Softimage has to update after each frame. It all boils down to efficiency. I hate waiting for a scene to update, and this way, I never have to.

In order for you to be able to swap animation files between two characters, Softimage requires that both 'actors' skeletons have the exact same skeleton structure. By this, I mean that both skeletons must have the same number of bones; as well the bones must share the same names between skeletons. For example, if we are dealing with the leg bones of two characters, both bones must be named by the same convention. If they have different names; or even one letter or number is different between the two, the animation swap will not work between those particular elements. This same principle applies to your characters rig if you are using one. See the character rig tutorial for information on how to build an efficient rig.

The prefix of each object does not need to share the same name between the two characters, nor do you need to enter a name in the prefix line at all. I usually use the prefix to describe the type of action that my low-res actor is performing.. I.e. a walk, a jump, or run. This allows me to look into my ANIMATION folder and easily select which animation file I need to apply to a character in a given circumstance. It is the prefix at the top of your character's hierarchy that shows up in your ANIMATION folder as the animation files name. This way, you can create an entire library of actions for a character, and call them up at any given time.

Open your schematic window, and activate MOTION mode from the viewports mode menu. Find the top node of your characters hierarchy. You will notice that there is a yellow line coming off that top node with the word ANIM located somewhere along that line. At the end of this line is a 4 sided rhombus. This rhombus is your characters animation file. The file contains information regarding every animated piece of your character. As a rule, it is always connected to the top of your hierarchy. In our example, using the low-res and hi-res twiggy character, this top node contains animation Info regarding Twiggy's bone rotations, Null Constraint animation from his arms and legs, as well as up vector animation that controls the resolution planes of his arms and legs. The important thing to note is that this top node named PUPPET is the parent of the Twiggy character as well the parent of his Rig.

Select the top node of your character as a Branch or Tree in single mode. Make sure you are in the MOTION module and click on Save à Selected Elements à Animation. A pop up menu will appear asking you which Softimage Database you wish to save the animation to. Select your appropriate database through the DBList and when you are satisfied click on SAVE. The animation file will store itself in that particular database's ANIMATION subfolder.

You can now delete your Low-resolution character from the scene you have been working in. Again, as a word of caution, whenever you delete something, save your scene. Now, call up your Hi resolution character from its database by using the Get> Scene command. Your character will load up into the scene that you have been animating your low-resolution character in. Of course the Hi-res character will have no animation on it. In order to apply the animation file you have just saved, select your hi-res characters top node as a branch or tree in single mode.

Still in the Motion Module click on Get >from Library > Animation. Navigate your way to the database in which you saved your low-res characters Animation File. Highlight it and click on LOAD. Another menu will pop up asking you to enter an insertion offset. All this means is; at what frame do you wish the animation to begin. You can specify whatever frame you like, although if you are animating your low-res character to interact with a scene at a particular time, you will use the start frame of that original character.

Click on OK. Softimage will do the rest for you. If you look on your mouse line, it will tell you how many animation elements were matched up to your hi-res scene. As well, if you go into your schematic and activate MOTION mode, you will see that Softimage has taken the animation Rhombus from the low-res character you have been working on, and applied it to the Hi-res character. Now, you can render out your final version of your perfected scene.

Low Res Hi Res animation swapping was written by Adam Sale. Adam is a Technical Director and co-founder of Joncrow Entertainment. He can be reached at adamsale@home.com.