Rather than 'fly' Poser lights into an enclosed scene, I try to illuminate set by dialling any scene 'luminaires' to 'super-ambient'.

This is okay when the model part is split so the filament / bulb / source is allocated its own group, so its own texture. But what to do when entire luminaire --the bulb / tube, holder, shade, ferrule, cable & pattress-- forms one group, shares one texture map ?

Is there any way to 'mask' that shared texture map so that only eg the bulb region responds to 'super-ambient' setting ??

Alternative would need the model re-grouping so mesh for eg bulb may be allocated its own material, and that dialled to 'super-ambient'.

Not much of a problem when the set is low-poly but, if set's OBJ is 10~~20 MB with 60++ textures, becomes harder...

You can use a mask. Create a black and white image for the mask where the black is "off" or not illuminating and the white is the bright part. plug that into your ambient or emitter value, (where you tell poser how bight you want it)

Ah, like a transparency map ?? { Facepalm... } Thank you, I'll try that this afternoon after clinic for my 2nd 'Covid' vax.

Thank you. I made copies of the two room-lights' texture maps, flood-filled the un-lit parts with black in free Irfan View, used them as 'ambient' maps. Not obvious in 'preview', needed several partial test-renders, then lonnnng render to do justice, but seems to work. Currently running two recipe variants: 34 pix_sample Superfly Progressive on PC, 64 pix_sample Superfly Progressive on network render 'Box'. As latter system renders rather faster than former beyond its GPU cards' now-modest capacity, they'll arrive together and i'll post both for comparison...

Ooh !! I've just spotted a desk-lamp, no, two !! Are there more ? I wonder if I can recruit them...

Okay, Box did something weird and started over. Here's the 'local' 34 pix_sample render...

And the 64 pixel_sample render via Box...

FWIW, I found set had seven (7) desk-lights. Let's see what they can do....

Forgot to mention this is Richard Mandel's free SCG post of https://www.sharecg.com/v/97841/view/5/3D-Model/RE2-Source-ROOM20B-1F-East-Office

~8 MB OBJ imported at ~33% of original size. Note I had to edit OBJ in Wordpad as it sought MTL deep, deep within RM's folder tree, confusing Poser...

I masked and dialled the desk lights, also found the inner-office glazing material and dialled that to ~95% transparency. Turned camera to show 'reverse angle', adjusted 'hither' to hide the wall and its heaped boxes. Sent 96 pixel-sample Superfly render to Box. ~75 mins later, I got...

if you want a boost from emitted materials in superfly, without super cranking the ambient value, the ambient boost shader in Superfly material sampler by seachnasaigh located here in freestuff works really great. Of course you'd still need your masking.

Thank you.

Again, thank you, bwldrd, for the advice. Applied to another Richard Mandel freebie: https://www.sharecg.com/v/97857/view/5/3D-Model/RE2-Source-ROOM20E-1F-Interrogation-Rooms

As-is, the strip and pendant lights dialled to super-ambient made their fittings, cables etc glow anomalously, too. I used their textures as templates for the ambient maps. Attached, so you can see what I did. A few test-renders with Superfly showed I'd need a lot of pixel-samples for a good piccy. I set 256, queued job to my network-render 'Box'. That ran ~1900 to ~0300, probably my longest since an 'overnight' P4. But, IMHO, worth it...

Just to clarify masking:

Lights: set luminaire's lit part(s) to white in Ambience mask, rest is black.

Glass, eg in door: set glazing to black in Transparency mask, rest is white.

Yes, I had an attack of the El_Stupido Face-Palms...