Hi. Everyone.
I have a question.
I need your help.
What is next?
I know the other option.
But I don't know - "Include existing groups in polygon groups"
Please teach me.

It will depend on what you are going to do with the OBJ after you have exported it.

Thank you Philc.
I respect you.
You are a great poser.
To exchange few words with you is in itself a privilege for me.

I want to know what can I do next option
"Include existing groups in polygon groups"
What is it?
Can you help me?

they don't actually explain that radio-button dialog in the manual AFAIK.
but if you add groups in group editor, that might be a good button to check,
in order to preserve associated material zones.

Thank you Miss Nancy.

I tested with aiko 3.
See below image.

First(Left) image is applied only first option - Include body part names in polygon groups.
And Second(Right) image is applied only third(fourth) option - Include existing groups in polygon groups.

But I don't know what is different.
Can you tell me a little more?

see att. img. - does obj export hierarchy have neck checkbox?

Yes.
You are right.
You are very kind to me.

But, I think it is not important.
What imortant thing to me is what is "Include existing groups in polygon groups"
Can you help me about that subject?

As Miss Nancy says, if you have not added any groups using the grouping tool then it will not make any difference when exporting a figure. I only use that option when exporting a prop and I wish the grouping to be retained.

Thank you!

I see now!

I offer you my heartfelt thanks for your favor!

Technically the function of "Include existing groups in polygon groups" is to include any pre-existing group names in the obj file you are exporting. If you do not use this option every group in the saved obj file would be unnamed effectively making it all one group. This is often a bad thing. So unless you have a specific reason not to, always use the "Include existing groups in polygon groups" option.

If you look at an obj file in a text editor, each group is preceded by the letter g followed by the name of the group (if any). Under the 'g' line you will usually find a 'usemtl' line which defines the start of a material zone. More info on the obj format at this URL: http://www.royriggs.com/obj.html

In a figure (cr2) each each group is usually assigned to a separate body part. Each body part has a joint and various joint parameters (collectively these are know as a "bone"), this is what allows the figure to be articulated. So groups are virtually essential to an articulated figure. As materials can be easily assigned to a group, groups also make it easier to assign different materials to different parts of an obj file, irrespective of whether that obj is used in a figure or a prop.

When I export an object I usually place a tick (U.S.=check) in the "Include existing groups..." and "As Morph Target..." boxes, and leave the other boxes blank. If you use the "As Morph Target..." option when exporting, it will ignore any translations rotations or scaling that have been applied to the figure (or prop), and in this respect it will be like you cloned the object directly from the figure's base obj file, except that this option will still preserve the effects of any morphs or magnets that have been applied. Whether or not you use the "As Morph Target..." option, will depend on what you are trying to do. In the accompanying graphic the  head exported with  "As Morph Target..." has loaded centrally and without any rotations, even though the figure it was exported from (on the left) was translated and had rotations applied.

I have never found a use for the "Include body part names..." or "Include figure names..." options. I feel they only add unnecessary complications and are best left blank. I'm not sure exactly what the "Weld body part seams" option does, but in a figure the welding happens in the cr2, so it is unnecessary, and probably undesirable to use this option when the exported obj is for use in a figure.

Quote - I have never found a use for the "Include body part names..." or "Include figure names..." options.

These are useful if you're exporting multiple figures to another application to avoid cross figure groups getting formed on import.