Attached Link: Collada - the parent site

Ok, the standard *.obj file format does not carry information about skeletons (bones), nor skinning information (weights on the vertices of the mesh that tell the mesh how much to respond to changes in the bones positions). So, if you export a rigged model into the *.obj format, this information is stripped away and lost.

However, Jeff, the *.obj format does carry information about scale, it carries information about the central axis for the entire model, and it regards "Y" as "up." It does not carry information about the locations of pivot points other than the central model axis. If you have pivot points on sub-components, such as doors, these will be stripped away upon export to *.obj.

So, if you are making your models quite large, you probably should reduce their scale just prior to export, to be safe. In most applications that someone would import an *.obj model, it is far easier to locate and re-scale a model that appears too small in that application, than it is to locate and re-scale a model that is way too large for the viewport of that application. If you did not center your model and force the model axis to be at "0", "0", "0", and the model is too large, it will be almost impossible for the user to locate and re-scale your model to fit well within their application.

Collada has several versions, and before using it, you should inform yourself about the basic content of the format. For this purpose, you should go to the website I listed above. This web site describes the information carried in the general version, provides links to downloads for some of the specialized importer/exporters, such as for MAX, and provides testing tools so that you can "see" how well your model might appear once translated into Collada format.

Please note that many applications, such as Daz Studio, MAX, Poser, Sketchup and so forth have implemented their own versions of a Collada exporter within their application. These custom-built exporters may or may not have all the features of the primary Collada export/import program, or they may have implemented an older version of Collada that lacks all the features of the current version.

Collada carries all the information common to the *.obj and *.3ds formats (scale, axis location, color), but it does not assume that "Y" is always up (Thank God!), most versions carry information about groups, about the pivot points of sub-components, it carries skeleton and skinning information, some IK information and some information about animation.

If you have software programs that always maintain the current versions of Collada in their updates, you can have everything translated well, including the most complex animations. However, almost all the major 3d programs neglect Collada in their updates, and it is rare to find a complete translation of all the information Collada makes possible. It is rare to find anything other than the Autodesk products that always allow full translation of IK systems. And then there are kinks associated with particular products. Vue, for example, easily allows importation of simple animation of a model (movement of the whole model) information that came via any Collada exporter, but only the MAX Collada Exporter seems to send more complex information (a walking cycle, for example) into Vue. If I wish to rig a dolphin in Maya and animate it in a swimming motion, for example, I actually have to transfer that dolphin mesh to MAX, rig it all over again, animate it there and then use the special MAX Collada Exporter to get that swim cycle into Vue successfully. Rather more work than it is worth!

So, good practice is to use the Collada testing tools to look at your Collada exports, and then you'll just have to experiment to learn the specific limits on Collada imports into programs like Vue.

As to your concern, Jeff, for getting visible seams on meshes under scale changes, that should not be a problem in either the *.obj or *.dae file formats. The only circumstance I think that where it would be a problem is if your texture file is too small for your model (or model component) to begin with, or if you have quite visible seams to begin with. (It is not going to have anything to do with the import or export function.)  You can determine if you have visible seams or too-small texture files by scaling up your model and taking a look at it in close-up view, of course.