Using the Skin Data Utility function in 3dsMax

[Hannibal Smith]

Title: Using the Skin Data Utility function in 3dsMax
Posted by: Hannibal Smith
Modding area: Modelling Units
Required programs: 3dsMax, Vercingetorix's cas import/export script
Summary: This guide will introduce a function of 3dsMax which will help when weighting models. Although this tutorial has demonstrates a very simple procedure, I believe that this utility will be even more useful for more experienced modellers due to the fact that they will be making models with larger vertices counts.


Introduction

Although I now sort of know my way around 3dsMax I have no history of using the program before I started modding RTW. As such I'm still learning some of the functions and tricks this program has to offer. This is something I learned only yesterday and thought I'd post a tutorial.

When making a new model you will often merge together pieces from different sources, when doing this you unfortunately also lose the vertex weight data associated with the skin modifier. The Skin Utility function of 3dsMax can help retain the vertex weight data so you won't have to re-weight each vertex.


Preparation Work

For the purposes of this tutorial I will be showing you how to take the head from a roman hastati and merge it to the body of a barabrian infantry model.

Firstly open your base model (in this case the barbarian) using VG's script. Now select the model itself in this case it's called body_400. In the upper right hand corner of the screen look for a hammer icon, then press the more... button. This will bring up a menu, from this select skin utilities.

Spoiler Alert, click show to read: 

A menu will appear on the right select "extract skin data to mesh"

Spoiler Alert, click show to read: 

You will now have a copy of your model which has baked into it all of the weight data from the model. This will be called SkinData_Body_400.

Now go ahead and select the model body_400 and remove the skin modifier. Then using the element option in the modifier menu select and delete the head. Using the same procedure delete the head from the SkinData_Body_400 mesh. Save this file for later.

Spoiler Alert, click show to read: 

Open your hastati cas and repeat the procedure above expect this time delete everything but the head, on both the model and the SkinData mesh. Again save this as a max file.

Spoiler Alert, click show to read: 

Merging objects together.

Open your original max file the one with the headless body. Select File --->Merge. Select the max file which contains the hastati head and then make sure that you select the SkinData mesh as well as the head model to merge.

Spoiler Alert, click show to read: 

In this case the name of the hastati mesh and the barbarian are the same so go select autorename on both the merged objects.

Ok now you should have 4 meshes, 2 model meshes and 2 SkinData meshes. So far other than the skindata its just a normal merge. So we want to now attach the head of the hastati to the barbarians body. At this stage I recommend that you hide the SkinData meshes just to make life easier. Select the barb mesh and in the modifiers menu select attach the click of the head.

Spoiler Alert, click show to read: 

Ensure that the vertices of the head match up with the vertices of the neck. Using the snap to vertices button in the top menu is useful when doing this.

Once this is done add a skin modifier to the mesh. Add all the bones from the skeleton.

Spoiler Alert, click show to read: 

At this point now we would normally be starting the process of weighting the model, but this time we done have to.

Hide the model mesh, and unhide the 2 SkinData meshes. In the same way that you attached the 2 model meshes together attach the SkinData head to the body.

At this point it important to mention that what ever you do the model mesh you must also do to the SkinData mesh so if you have moved some verts from the head to match up with the body this must be replicated on the SkinData mesh.

Ok now unhide all you should have a model mesh and a SkinData Mesh select both meshes.

Go back into the Skin Utility menu, in the same way you did at the start. This time however click "Import skin data from mesh" the following menu will appear.

Spoiler Alert, click show to read: 

In this case we just select "match by name" and then Ok. All of the weight data has been transferred to the model mesh. At this point I would go into the weight table and just check that the data has been transferred.

Then the model should be ready to go.

Spoiler Alert, click show to read: 

Although this tutorial has demonstrated a very simple procedure, I believe that this utility will be even more useful for more experienced modellers due to the fact that they will be making models with larger vertices counts. I'm in the process of making a body model with a large number of vertices, and found it easier to separate the model up into component parts like arms, legs, torso and head and weight them separately. This utility allowed me to re-attach all of the pieces together and still retain the skin data.

I'm by no means proficient with this utility yet, but as I had never heard of it until yesterday I assume that may other will be in the same position, I recommend that you give it a try.

[hæressiarch]

great tip my friend thank you so much for making moders life easier +REP! you deserve at least dozen of them

[Salvor Hardin]

For unexperienced modellers like me, this tutorial is going to be extremely useful. Thanks a lot!

[Hannibal Smith]

I think that as you become more experienced, the more useful this method will become. It will allow me to weight the model just once, I cant tell you how many times I have weighted the model I'm currently working on. Each time I change any detail like moving a vert I had to reweight everything. Now if I change the arms I just have to re-weight the arms and update the SkinData model, and if the change is only slight I dont need to change the SkinData model at all. I think it could be really useful

[Boom S]

HS, I need a bit of help, I need to edit some vertices on an unit (I need to change the proportions of the unit, so it's not a small change). that I can manage quite easily but the skin weight thing is driving me nuts.

could you guide me a little ? what do I do after copying the skin data ? I don't think the changes in my case are small enough that I won't need to re-weight and this is beyond me at the moment !

[Hannibal Smith]

What exactly are the changes you need to make? can you post a picture.

Once you have exported the skin data it will make a mesh called skindata_modelname. When you import back the information transferred is from space orientation rather than say vertex number. So if you can make the same changes to the skindata mesh, there is no reason why you cant import the data back without having to totally re weight everything. Remember it doesnt need to be exactly the same just close.

To be honest I never intended this tutorial to replace learning how to use the skin modifier, just to make it easier.

[Boom S]

it's not that I'm averse to learning how to use the skin modifier, I'm not asking for detailed help either.
if you can tell me how to re-weight after editing even one vertex I'll manage the rest.

just the simple steps, not detailed explanations, I'll ask for clarifications if I need them. from Satanus' tut it seemed to me that these are the steps
(this is on an existing model)
1. select body_400, >> edit poly >> move vertices as you need to
2. add bone
3. weight vertices

It is 2 and 3 where I'm getting confused. if I'm moving vertices in the head only do I need to add all the bones ? also, no vertex seems to be highlighted when I click the vertex option as Haile Satanus' tut says it should(I selected all the bones except the bone_abs and the 3 bone_cloaks).

[Hannibal Smith]

if you can tell me how to re-weight after editing even one vertex I'll manage the rest.

The point is that inorder to move that one vertex you must first collapse the skin modifier that is already on the mesh. So you will need to re-weight each vertices, the leg, arms and torso even if you just change the position of one vertex in the head.

Your work flow will be

1 select body_400 --> collapse skin modifier --> move vertices
2 Add skin modifier and add all bones.
3 Weight each vertices.

The point of my tutorial was to show how to avoid re-weighting everything so just to run with your example if it was just one vertex in the head that had to move then you could still import the skindata from the original model, it would still be close enough.

However you have already stated

(I need to change the proportions of the unit, so it's not a small change).

I was asking for details to see if the changes are small enough to use the skindata method or if you'll have to re-weight each vertex, which in fairness is not what my tutorial is about.

[Boom S]

as a matter of fact I have to do two projects, one with major changes another with minor. I mentioned the major one since that was keeping me busy at the time. therefore your tutorial is useful for me !

well, I made an attempt,
>imported CAS file
>copied weight data into skin-body400
> deleted skin of body400
> minor adjustments to a few vertices in body400
> similar adjustments to skinbody400
> added bones to body400
> transferred weight data to body400 (how does one check if the weight data was actually transferred?)
> deleted skinbody400
> exported as CAS
> cleared everything and imported as CAS but there's an error message and the half the file's missing

[Hannibal Smith]

to check that the data has transferred you must select the skin modifier and then on the right hand side of the screen you'll see a button called "weight table" this will show a list of all the numbered vertices just check that each vertex is assigned to just one bone ie has a 1 in just one box and the rest are 0's.

[CPT Worsham]

This will be called SkinData_Body_400.

When I select "extract skin data to mesh" I don't see where the name of the body changes to SkinData_Body_400. Am I supposed to write that name in myself? I'm using 3ds Max 2010 by the way.

Also, how do I remove the skin modifier? And yes I am a complete noob.