I collect fun models from a variety of sources. Some are 'Poser-friendly' formats, some must be variously ported, wrangled, re-textured...

I'm used to 'rigged' FBX figures etc giving me a world of woes. Though there are honourable exceptions, FBX may import as 'many' sub-rigs, often intractable. They may 'explode'. They may even be 'invisible', have a shadow but no 'body'. 

I never expected to meet 'invisible' OBJs. Hey, they're a 'classic' format: What could possibly go wrong ??

I'd pulled in a very nice DA freebie, a port from decades-old PSP game.

https://www.deviantart.com/quake332/art/The-Lord-of-the-Rings-Tactics-Weathertop-906486860

Quake332 had used Ninjaripper to convert 'Weathertop' scene to OBJ+MTL, latter correctly calling PNG textures. I could see I'd have to extract several transparency masks from their alpha channels. Not a problem. Free Irfan View is your friend....

($$) 3DOC correctly loaded and previewed mesh and textures, though could not grok the alpha channels. I could see where such were pasted onto 'flats'. Classic PropViewer32 correctly loaded and previewed mesh, un-textured, but with transparency masked by those alpha channels. So far, so good.

I imported model to my PoserPro_11.3 at 'ground zero', 100% original scale. Couldn't find it. Scaled all the way up to 100k%, down to 0.001%. Still couldn't find it.

Deleted, re-imported at 'ground zero', 100% figure scale. Couldn't find it.

After scratching my head, I tried to open model in Windows' Paint 3D. Bloop !! "Something went wrong."

Windoes' 3D Viewer was okay, as were Noesis and Open3D Viewer...

Curious, I opened the OBJ in 'WordPad'. It was an unusual format, ~300 mini-OBJs concatenated. I've seen such in free RE 'Recreated' scene mega-ports by DE's prolific Richard Mandel, but his work...

So, I opened the model in ($$) 3DOC, re-saved it.

Now, it imported correctly to Poser, either as %original, or %figure.

Downside was all those mini-OBJs each had their own material call. Although 'Diffuse' loaded, Poser did not recognise the Alpha channel. Fortunately, there were only a dozen or two skeletal trees, scrubby bushes and such, and it was easy to hand-apply their transparency maps. Thankfully, most were near start of material list, as Poser's UI does not work well beyond ~40. I nailed the last few by clicking their flagrant 'flats' in Material Room preview.

Along the way, I saw how to paste transparency calls into MTL. For each alpha mapped texture call, eg

map_Kd 000002248A4649B8.png

I used Notepad to add...

d 0

map_d 000002248A4649B8Alpha.jpg

Please may we have much longer fields for 'image source' entry ??

A couple of days later, I had exactly the same 'No-See-Um' issues with another nice model, a Quake332 'Ninjaripper' port of dark, brooding forest...

https://www.deviantart.com/quake332/art/Corpse-Party-Blood-Drive-Forest-904875803

Same solutions, albeit for only ~65 material calls, and looks good...

- -

I've no idea why Poser and Paint 3D 'fell over', as my initial suspicion that those ~315 sub-objects were to blame was falsified by the forest's ~65...

I looked up the weathertop .obj and indeed it has a weird setup.

If you think the sheer number of objects is the issue, best try to extract one in a file editor and see if it loads. 

Facets are defined in 4 domains instead of the usual 3. The 4th domain 'vc' I could not find a description of. Not sure if this is standard.  Some interpreters may simply ignore this extra information but others may get confused.

Well spotted !!

'vc' is not even a 'deprecated' thing, it is simply not mentioned or documented by 'Alias/Wavefront' info, the deposited 'Library of Congress' format or anywhere else...

It should not be there !!

I can't find any obvious way to contact NinjaRipper's author, so I'll contact its user.