History Deletion

# 1 03-04-2014 , 06:49 AM

Registered User
Join Date: Apr 2014

Posts: 2

Good Morning/Afternoon/Evening All,

I've decided to take a plunge into 3D Modeling/Animation(this appears to be a bottomless rabbit hole), and have been working with Maya 2014 for the past few days. One thing I've noticed that keeps popping up in the tutorials that I've been viewing is History Deletion. The tutors in the videos are pretty adamant about doing this at certain points during the modeling process, and I follow along and complete this step but I don't really understand what exactly it's doing.

Does anyone know of a good resource on the interworkings of history and history deletion? The questions I have are as follows:

What is logged in History?
Where can I see this historical information?
What is happening when I delete history?
When I select Edit > Delete by Type > History, is this deleting only a specified deletion or is it deleting ALL history?
How is Maya handling this on the backend?
If I don't delete history, what effect may this have in the future modeling process?

I think my real confusion on all of this, is that while the tutorials that I've watched shows me HOW to do something, it doesn't explain to me as to WHY I should do it and often leaves out the specifics of how the application is handling the commands I'm giving it.

Any help on this would be greatly appreciated.

Last edited by Elynole; 03-04-2014 at 06:51 AM.

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# 2 03-04-2014 , 09:25 AM

Subscriber
Join Date: Jan 2004

Location: Bolton - UK

Posts: 2,457

I dont know fully why but having too much history does causes problems. I think of it as sketch marks on a drawing - it helped you get there but they mess with the final product.

In the past some problems I have hit is 1) slowing down the program as its storing alot of unneeded data. 2) tranlation and rotation errors, due to multiply unneeded inputs 3) grouping and dupulation problems.
Again not sure why these problems come up, just know that keeping clean messes by deleting the history is a very good start to fixing them.

One thing I do know is that delete history only effects the object you have selected. If you look the option to delete all history is the next option down in the menu.

Hope you get your answers.

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# 3 03-04-2014 , 10:44 AM

EduSciVis-er
Join Date: Dec 2005

Location: Toronto

Posts: 3,374

Maya is based on a graph of connected nodes. You can see this most clearly by creating a cube and graphing it in the node editor.you will see a creation node which provides info on how the cube is made which passes that info to the shape node, which is the main node for your Geo. Certain operations like extruding or revolving nurbs will also have their own node, also passing info into the shape node. That is why they are listed under inputs in the channel box.

Now this is good because the flow of info is live and dynamic. For example, you can change the number of cube divisions in the creation node even after your cube is created. Or tweak a curve and the revolved surface will update accordingly. So having that history intact is great for making those afterwards edits.

But, you can see how this slows down calculations because maya has to pipe the info through many nodes after a while just to draw your shape. When you are finished with the input nodes, you can delete history and maya will bake all that info through the input nodes to your shape node / Geo. Now maya has fewer calculations to do and it takes less memory.

I hope that makes some sense. It takes a while to get familiar with how things work, but if you think about it all in terms of connected nodes, you will understand much more.

-stwert

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# 4 03-04-2014 , 11:33 AM

Lifetime Member
Join Date: Apr 2007

Posts: 73

RE: History.

The way it was explained to me. was simply 'Every time your view of your scene/viewport changes in anyway, Maya has to redraw your objects on screen. It does this by taking an (.obj plotted data type mesh) and then applying all the things you've done to it since'

If you have never deleted your history, this means Maya takes a poly cube (lets say) and performs thousands of calculations ( Hundreds of splits and extrudes - Each tweak to your model recorded the translation/rotation of each single vert that changed in any way) And then redraws this final calculated mesh on your screen.

As you tumble even one model, this means redrawing the model many times per second... performing thousands/millions of calculations each time to do so .

Deleting the history stores your models current form as that initial (.obj type mesh data) and it then redraws it from this each time. The more history you have the more your system will 'Chug' - for lack of the correct word...

As Tweety said, I find I will get very odd results when duplicating/ making a sub-d proxy from a model with a chunk of history.... My understanding of history does not explain why it goes wrong.... it should just take longer right? this is why I didn't answer sooner... thought others would have a better answer.

But at its basic level that's why you should.

It doesn't explain why you cant create a poly cube move the top face up a little and THEN change pCube1 inputs divisions. Something so simple shouldn't trip it up if my 'facilitator' knew his stuff?

Learn from others mistakes, it takes too long to make them all yourself.

Last edited by 3dStudent; 03-04-2014 at 11:41 AM.

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# 5 03-04-2014 , 02:01 PM

Registered User
Join Date: Apr 2014

Posts: 2

Thank you all for your answers. I ended up beginning to read Mastering Autodesk Maya 2014 last night, and in it's opening chapter it goes into detail regarding history and the Node Editor, which was the sort of information I was looking for.

I think I'll stick around these forums, as everyone has been most helpful.

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# 6 03-04-2014 , 06:37 PM

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Join Date: Aug 2011

Location: Sliema Malta

Posts: 497

All 3D applications are seen as state machines. They are storing the state in the history and can recall that objects state depending on if you have maintained the history of the object.

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History Deletion

RE: History.

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