Animation and rig tool

[SPJ]

I'm not sure about those tools, so I can't answer that question. You can access all the help from this link:

https://knowledge.autodesk.com/search-r ... ation.html

Also, you can download the help files and install them on your machine to keep forever. Be sure to point Softimage towards the install location of the help files in the preferences.

Weight Maps help is here:

http://docs.autodesk.com/SI/2015/ENU/#! ... ty3507.htm

[opoppopopp]

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A magic happened one minute after I made the post. I turned the "Normalise" button off and the eraser works correctly now.
I feel like I have to ask about all of these buttons here since the official help is been removed from web.

1.What does the "Normalise" button do?
2. What is the differance between Abc and Add tool?
3. Why the add tool buttons are duplicated in the menu?

All your question is explained in the document.

You SHOULD turn normalize ON
- Let's say ONE of your point's is fully enveloped to ONE bone.
- At this time, you can't just erase its weight to this bone, because if so, this certain points will not have 100 weights across bones(the color will be BLACK)
- Just Smooth it a little bit, and then you can erase it weight.(as you already experienced, see below for why)

Generally XSI will make sure(which also user normally want) each of your point's weight is added up to 100, across all the bones it is enveloped to.
When you ERASE, let's say 10% the effect of deformer A, "normalize" will automatic rise other deformers's weights to this very point, so that its weights will still add up to 100%.

ABS and ADD is "absolute" and "added", they are useful when you brush opacity is not 100%.