YogAni - Yoga Animation

1. Introduction

YogAni (Yoga Animation) is a free experimental online service (yogani.tk) intended to establish a collective database of animated yoga exercises (asanas). Unregistered users can display and download yoga animations of other users. As a registered user, you can define the motions of a character during the sequences of an exercise by yourself. An online background rendering machine will then compute and render the single motions of your character frame by frame and assemble them into a downloadable animation.

1.1. A simple example

Assume, you want to animate a bowing motion of the upper part of the body. After you have created your own account (section 2.5) and signed in (section 2.4), press the New exercise button on the YogAni home page (section 2.2). A new empty exercise (named [illustration not visible in this excerpt] New exercise) is created in the list of your exercises.

Press the corresponding Edit button to open the Exercise page (section 2.7). Change the exercise name to something more descriptive like Hello world and press the New se- quence button to create a new empty sequence by the name of [illustration not visible in this excerpt] New sequence.

The corresponding Edit button opens the Sequence page where you change the sequence name to Bow down. Press the New move button to create a new default move ([illustration not visible in this excerpt] Skeleton rotate about the up axis 0).

Pressing the corresponding Edit button takes you to the Move page (section 2.9) where you click Chest in the Bone column, bend in the Motion column, and 30 in the Quantity column, which automatically returns you to the Sequence page. A second New move - Edit combination allows you to additionally bend the abdomen for 45°. The Sequence page should now list both moves:

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Change the Number of frames to 48 frames = 2 sec and press the Render sequence button. Wait patiently on the Render sequence page (section 2.12) until your sequence has been rendered and animated. You are then automatically taken to the Display sequence page where the animation immediately starts (unless you have not installed Adobe Flash Player). The animation should resemble Figure 1.

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Figure 1: A few frames of sequence Bow down

Now you want to add a second sequence to your exercise that rebends the upper part of the body back to the initial position: Click Hello world in the breadcrumb trail^[1] at the top of the page to return to the Exercise page (or click the Done buttons on the Display sequence page and the Sequence page). On the Exercise page you press the New sequence button and Edit the just created [illustration not visible in this excerpt] New sequence. Call the sequence Back up and create two New moves that bend the chest and the abdomen back to 0°. After setting the Number of frames of this sequence to 48 frames = 2 sec you can press the Render sequence button and wait until the animation of the second sequence is displayed.

Use the breadcrumb trail to return to the Exercise page. You should see both sequences checked as Valid:

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Press the Render exercise button. Both sequences are concatenated into the final animation of the exercise.

1.2. Hello better world

You want to elaborate on your simple example a bit. Return to the YogAni home page (remember the breadcrumb trail) and use the homonymous button to Duplicate your Hello world example. Click the Edit button of [illustration not visible in this excerpt] Duplicate of Hello world and rename the exercise to Hello better world.

First, you do not want to view the animation directly from the front but in a more perspective way from right-front. On the Exercise page, insert a New sequence and move it up using its Up button twice until it is the first sequence on the list:

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Edit the new sequence and call it Yaw 30. Set the Number of frames to 0 frames = static and insert a New Move. Edit the new move and make the [illustration not visible in this excerpt] Skeleton rotate about the up axis 30. After you render the sequence, you look at a static image under an azimuth angle of 30° (Figure 2a).

Next, you want to give the character a more relaxed initial position by lowering his arms.^[2] Back on the Exercise page you insert a new sequence and move it up to second position:

Edit it, name it Hands down, set the number of frames to 0, and insert four new moves that bend down left and right collars and shoulders.^[3]

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Rendering the sequence should compare to Figure 2b.

Finally, you want to rotate the feet to make the character “stand on the ground”. Insert a new sequence Feet up on third position:

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Make it static and insert the following moves:

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The rendered sequence is depicted in Figure 2c.

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Figure 2: Construction of the initial condition of exercise Hello better world

Since the first three sequences (Yaw 30, Hands down, and Feet up) are static (0 frames) they define the initial condition of the animation. Unfortunately, you have to render the dynamic sequences Bow down and Back up again, since you have altered their initial conditions. After successful animations of the last two sequences you can render the complete exercise. Figure 3 shows some intermediate frames of the final exercise.

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Figure 3: A few frames of exercise Hello better world

You might want to merge the three initial sequences into one sequence by two single merge operations on the Exercise page:

1. Press the Merge button in the Yaw 30 sequence. The current sequence (Yaw 30) and the next sequence (Hands down) are merged to a sequence called [illustration not visible in this excerpt] Merge of Yaw 30 and Hands down.
2. Press the Merge button in the new first sequence. The first and the second sequence are merged to a combined sequence, consequently called [illustration not visible in this excerpt] Merge of [illustration not visible in this excerpt] Merge of Yaw 30 and Hands down and Feet up.
3. Edit and rename this new initial sequence to Yaw 30, Hands down, Feet up.
4. Render the sequence and the exercise.

1.3. General hints

- Immediately rename new exercises and sequences.
- Rendering is very slow. Only render if necessary.
- Always render a sequence with 0 frames = static until you are completely sat isfied with the final position.
- Delete “test” exercises.
- Use the free DAZ Studio^[1] and the Export script (Appendix B.2) to prepare complex exercises.

2. Manual

2.1. Block diagram

Figure 4 displays the hierarchical YogAni block diagram.

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Figure 4: YogAni block diagram

The YogAni database holds an unlimited number of users. Each user can create an unlimited number of exercises. Exercises consist of ordered sequences, which contain one or more moves. A move is defined by the bone that is moved, the motion name and the quantity of the motion.

2.2. YogAni home

The YogAni home page (yogani.tk) is shown in Figure 5.

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Figure 5: YogAni home page

Its main content is a list of all valid (rendered) exercises of all users with the opportunities to Display (section 2.13) certain exercises or to Export (section 2.10) them in different formats; even if you are not signed in. You can search for exercises (or users) by typing a substring into the the search field and pressing the Search button. Additionally, you can sort the exercises by their name or by their owner.

A clickable breadcrumb trail at the top of every YogAni page helps you keep track of your current location and allows you to quickly navigate to higher site levels. In the top right corner you find the Sign in button for the creation of a new account (section 2.5) and the sign in of a registered user (section 2.4). A Documentation link at the bottom of every page points you to the document you are reading right now. The Contact link offers you additional information about the program and its author (section 2.3).

Figure 6 shows the home page after a successful sign in.

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Figure 6: YogAni home page (signed in)

The Sign in button has changed to a Sign out button and you can now Edit, Dupli- cate, and Delete your own exercises. The Edit button takes you to the Exercise page (section 2.7) of that exercise. The Duplicate button of an exercise (e. g. called An existing exercise) duplicates it (including all sequences and parameters) into a new exercise by the name of [illustration not visible in this excerpt] Duplicate of An existing exercise. Since the name of the doublet starts with a non-ASCII character ([illustration not visible in this excerpt]) chances are high that it will head the alphabetically sorted list.

Beware if you press the Delete button of an exercise, it is deleted immediately and irretrievably!

A checked Valid checkbox indicates that an exercise has already been rendered. Only your valid/rendered exercises are visible to other users. If you try to display an unrendered sequence a warning is issued (Figure 7).^[4]

The New exercise button inserts a new empty exercise named [illustration not visible in this excerpt] New exercise at the top of the list. You can import XML transfer files (section 2.11) by pressing the Import exercise button.

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Figure 7: Warning (display)

Sign out

If you check the All users box and try to edit or delete exercises of other users you receive the warning displayed in Figure 8.

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Figure 8: Warning (edit or delete)

2.3. Contact

The Contact page nomen est omen presents different ways to contact the author of the program and tries to clarify that YogAni is an ever developing noncommercial research project without any obligations (Figure 9).

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Figure 9: Contact page

2.4. Sign in

The Sign in page (Figure 10) allows a registered user to sign in for the manipulation of his own exercises.

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Figure 10: Sign in page

Additionally, the page offers a Create new account button leading to the homonymous page (section 2.5). If you enter a valid user name but a wrong password, a Reset password button is displayed (section 2.6).

2.5. Create new account

You can register as a new user on the Create new account page (Figure 11).

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^[1] With the breadcrumb trail you can easily navigate back to higher site levels. If you are lost, clicking YogAni in the breadcrumb trail will always return you to the home page.

^[2] DAZ Studio like many other 3D animation programs defines the initial (zero angles) character position having raised arms, slightly bended elbows and knees, and relaxed hands and feet.

^[3] Note, that left and right down motions have different signs. This is due to the opposite orientations of the local coordinate systems of the left and right bones. You will be irritated by and annoyed with that at first; but you will get used to it .

^[4] Unfortunately, there is no easy way to disable single link buttons in a gridview control in Visual Studio. Therefore, it is not (easily) possible to disable the Display link buttons of unrendered sequences.