Volume HUD in Bonus Tools

[FalconCrest]

Looking for someone who is familiar with the polygon area and poly volume HUD from the Bonus Tools, I don't understand how what they are calculating with regards to the mesh, I know that sounds somewhat vague, maybe someone can shed more light on it, then my question will or can become clearer ? 🙂

[pshwayka]

The other cool thing about that tool is you can click on those values and edit them on the fly...and if you click on the curvy arrows, you can rotate the object by entering values.

[FalconCrest]

When I do the multiplication on, in this case, not a cube, the math doesn't add up remotely to what the volume HUD is displaying ? 😞

[pshwayka]

I was going to ease you into that next topic.  

Keep in mind that things like spheres have a different volume calculation...and for objects that don't have straight edges, I'm sure the math gets pretty complicated.

[FalconCrest]

I redid the calculation turns out things are more or less correct for Volume Surface ^ 3 in the Bonus Tools, the calcuations gave me for example, 20.xxx for an object while the bonus tools will drop the zero and fire the results 2.xxx instead. 🙂

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@pshwayka wrote:

I was going to ease you into that next topic.  

Keep in mind that things like spheres have a different volume calculation...and for objects that don't have straight edges, I'm sure the math gets pretty complicated.

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The volume HUD gives good results for non-straight edge objects as in my example I mention previously, try it yourself 🙂

I have a question, suppose your mesh, including all the objects that belong to the mesh are smaller then their physical size, for example, you modeled a latern, after modeling you realized the volume of the mesh, including all the objects that are part of the mesh are too small, the total size of the latern is 8cm (height) x 4cm (depth) x 9cm (width) you need to set the physical size of the mesh to 7" (height), 5.76" (depth) x 6.2" (width) is it possible to do this in one pass, rather then manually scaling each part of the object of the mesh to size hoping everything scales physically correct ? If you get the physical scale of the latern correct, all the object pieces of the latern will more or less scale, adjust to physical size ?

[pshwayka]

Actually, I had already tried the volume tool on a sphere...so I knew it worked. 

For your scaling, you could probably select all the objects in your mesh, group then, center the pivot on the group, and then scale. You would probably want to create a temporary object that is the height that you want the lantern to be (for reference) since entering the height in the scaling numbers for the group would not necessarily correspond to the lantern height.  (hopefully that makes sense...)

[FalconCrest]

Hrm, If you had the volume^3 for the physical lantern and could translate this to the grouped mesh you could get near, if not perfect scale equivalency ?

[pshwayka]

Actually, that would be a great way to do it.  In the example you provided above, consider that 7" = 17.78 cm.  If you divide 17.78/4cm, you will get the scaling factor that you need to enter into the xyz scale fields for the group (4.445)

Try it!

[FalconCrest]

Don't you mean 17.78/8cm as the mesh is 8cm in height as per my example 🙂 ? That is 2.225cm considering the unit of measurements is CM ?

[pshwayka]

D'oh!  Good catch.  

There were too many dimensions in your post, and I got dizzy...

[FalconCrest]

🙂 No problem.

If the lantern is 8cm in height in Maya, and I divide the height of the physical lantern which is 17.78cm by 8cm that equals 2.2225cm that doesn't sound right, that is a smaller number to enter in for Y in Maya then the original height is of the object in Maya which is 8cm ?

[pshwayka]

Remember...you're not entering actual dimensions.  You are entering scaling amounts.  For example, If I create a cube that is 3x3x3 and then enter 2,2,2 in the xyz scale fields, I will end up with a cube that is twice as big as the original...or 6x6x6.

[FalconCrest]

Maya is multiplying the scaling ?

As you said, if you enter in 2,2,2 for a cube that is 3x3x3cm you'll end up with a cube twice as big or 6x6x6 that sounds as if Maya is multiplying the scaling ?

[pshwayka]

Exactly. 

[FalconCrest]

Is there not an equation whereas you can enter in exact values, in which Maya won't multiple ?

For example; if a cube that is 3x3x3 cm and because Maya multiplies the values which turns out to be 6x6x6cm. In my lantern example; 17.78/8cm equals 2.2225cm multiple due to Maya scaling which turns out to be 4.45cm the math is not correct, the lantern is too small in Maya.

[pshwayka]

If your lantern is currently 8cm tall, and you enter 2.2225 into the scale values for x,y, and z...the lantern will scale proportionately, and end up with a height of 17.78cm, or 7" in height.

[FalconCrest]

2.2225 * 3 equals 6.6675 (or less if multiplied by 2) ?

I wouldn't enter in the height into the width (X) for the lantern 🙂

[pshwayka]

You shouldn't be entering anything into the height or width. You are supposed to be entering a scale. And why are you multiplying by 3?

[FalconCrest]

I did say multiple by 3 or 2 !
I know you don't enter anything into height or width, you have to enter in 2.2225 into x,y,z which as you said gives you 17.78cm, how is this calculated by scale ?

[pshwayka]

You said you have a lantern that is 8cm tall...and you want it to be 7" tall, which is equal to 17.78cm.  8cm * 2.2225 = 17.78cm.

Since you don't want your lantern out of proportion after you scale it, you need to enter the same scale factor into the x,y, and z scale fields.

Note:  You should freeze the transormations on your lantern before scaling it, so that you start off with scale factors of 1x1x1.

[FalconCrest]

By entering 17.78cm into x,y,z scale, you sure that will equal the lantern to be the following physical dimensions of; 7" (height), 5.76" (depth) x 6.2" (width) ?