Thanks for the help, it is very much appreciated!
I will move on too as this is offtopic now, strictly speaking.
Now i got a got lead and will eventually figure it out. 

really cool project! photogrammetry with q3map2 and darkplaces is something I've wanted to experiment with for a while now.

quick question, why are you lightmapping this model? It's so dense why not just vertex light it? your results will be very good and cause fewer headaches.

you *can* lightmap something like this, but it can be a pain, as you've found. this will get worse in an actual scene with more complex lighting (like bounce).

don't underestimate the power of vertex lighting ;)

a test: https://imgur.com/a/e2lIirT 

@kp, from the other thread, apparently the lightmapping is forced on anything that exceeds 1024 verts. That is, as long as "-meta" switch is on, which is the recommendation everywhere I looked.

1024 per surface would be alright actually, but contrary to that post, in practice bsp seemed to split the model into max 128 vert chunks here (while in the source default maxLMSurfaceVerts is 64?)

@wakey, if you do end up using vertex lighting, you might want to at least subdivide the top of the foundation a bit, so the lighting isn't stretched. 

vertex lighting after all.
Very beautiful screenshots @killpixel!
How did you get to be just vertexlit?
Leaving out -meta alltogether?

In general i would have no problem with leaving the -meta stage out, if i understood what the drawbacks of that actualy might be.

My guess is that -meta in reality might only be relevant for true idtech3 games, as those have a actual problem with surfaces exceeding 1024 verts, most notably Q3A itself.

With darkplaces on the contrary -meta seems to mess things up, not only for the models, but i also noticed some brushsurfaces not beeing properly lit by rt-lights when using -meta.

@chedap: thanks for the tipp, will do that. 

the test I posted is using -meta. from the wiki (which is probably pretty outdated):

At one time, there was a clear definition as to what, exactly, the -meta switch did. Now, it has become the "magic" switch that is required for most of Q3Map2's advanced features. Always -meta, and always -v.

I was under the impression it grouped neighboring triangles into larger lightmap islands because that worked better for things like phong shaded terrain.

Anyway, I forced vertex lighting on the model with a simple q3 shader script:

models/dev/maria
{
surfaceparm nolightmap
{
map models/dev/maria.tga
rgbGen vertex
}
}

surfaceparm nolightmap prevents lightmap generation, and rgbGen vertex tells the texture to grab the vertex data for shading.

I recommend learning more about q3 shaders. they're quite powerful, even with DP's limited implementation.

chedap is right, you should add some loops to the foundation and base if you're going the vertex lit route.

also, I'd avoid clipmodel (spawnflag 2) for a model this detailed - use a clip brush instead. 

could have thought of surfaceparm nolightmap<q/> myself, as i am familiar with q3 shaders ^^'
Anyhow, the model now looks as intented:
https://imgur.com/a/8Co4bUs

Thank you a lot, killpixel & chedap!

In return i could answer any questions regarding photogrammetry, if there are any. 

good luck with the project, looking forward to seeing more of it 

who made this https://www.youtube.com/watch?v=SPWhp3KDxqM
shambler model. Is that Chillo's ??
the hands look diff. I just wanna give credit to my video. 

HD Shambler 

https://www.youtube.com/watch?v=qi7iLEolsn8