So, I wanted to export a neat MMD PMX 'stage' freebie to OBJ+MTL to use in Poser...
https://www.deviantart.com/shyuugah/art/MMD-Stage-DL-Corridor-887050518

01: Unpack using eg free Bandizip with its local 'code page' set such 'Asian glyphs' do not turn into 'dipthong alphabet soup'.
02: Use free PMX Editor to rename all materials and texture calls to English. eg 材質1 becomes 'Material1', ランプ1 becomes 'light1'...
03: Export to OBJ+MTL. Here, the ~8MB PMX becomes ~22MB. Import to Poser, iterate scale to taste. Here ~2.5%

04: As Poser_11.3 does not reliably auto-extract 'Alpha Channel' from mapped textures, deploy free Irfan View or, for eg DDS, free XN View.
05: Hand-apply those Alpha Channel maps to 'Transparency', 'Emission' maps to Ambience and/or Cycles' 'Emission' node.

Uh, why are my scene's texture maps up-side down ?
Yeah, yeah, PMX is opposite-handed to OBJ, also I may have told the PMX to 'render both sides'...
No problem: Rather than run all the texture files through eg Irfan View, vertically flipping, I'll just tick the 'Mirror_V' box in each 'Color_Texture' node.
Uh ? That should have worked, but did not...
Plan_B: clear that tick-box, set V_Scale from 1.000 to -1.000.
How odd ! That did not work, either...

At that point, I went for a belated snack-meal. Returning, re-fuelled and re-caffeinated, I found that Poser had sorta 'caught up' and flipped the texture.

For the next hour or so, as I changed textures' V_Scale to -1.000, most worked instantly, some took a few seconds, some needed a minute or two...

No obvious pattern / correlation 
Any idea what's going on ? Or how to 'nudge' Poser to refresh ??

This Superfly, progressive, 96 pixel-sample render took ~15 hours on networked 'Box'. Still a tad fuzzy, so I re-ran with 256: Now on 93%...

Just wild speculation as I haven't played with that feature:  some textures take longer to calculate.  If you want to test that hypothesis, see if you can find some correlation with the ones that were nearly instant, the ones that took a few seconds, and the ones that took a minute or two.  Since it's a simple V flip, complexity of the image probably isn't a factor.  Size, OTOH might well be an issue, especially as it probably has to buffer its translation efforts in a duplicated copy.  If size doesn't seem to be an issue, check to see if there are alpha channels in some and not in others.

That's the best I can offer.  Hopefully someone who know what they're talking about will come along and help.

Good call, Thalek.

Though SmithM were somewhat reticent about Poser internals, perhaps Bondware's gurus may be aware of potential processing pinch-point, and if still exists in #12 / #13...

NikKelly posted at 8:37 PM Fri, 12 May 2023 - #4465137

Good call, Thalek.

Though SmithM were somewhat reticent about Poser internals, perhaps Bondware's gurus may be aware of potential processing pinch-point, and if still exists in #12 / #13...

Does that mean it was an image size issue? I hope all is working reasonably well.  If it is an image size issue, I can' imagine how someone would work around that without modifying the image files.

Yeah, not too many companies want to share their internals, except for the ones they deliberately publish for creating plugins and such. Intellectual property aside, it's a little like giving burglars the blueprints to your house, at least in their eyes.

Tried that vertical mirror thing on Sasha-16's default bitmap for the face, its' 4096x4096, it took less than 1 second to flip it vertically using the -1 scale on my aging i7 8700K,.
I've got the feeling that the time needed to invert the bitmap using the scale is only the time to load it: on a 16k HDRi it's immediate as long as the node's preview is off

Note that the MIrror_U and Mirror_Vare used when tiling, as stated in Poser's documentation.
And don't worry: I ignored it till now: it was about time to read the doc because I used to wonder why, too... 

Y-Phil, thank you for that clarification.

Whatever the reason for the 1.000 / -1.000 delay, knowing there may be a delay yet it will 'come good' makes it 'usable'...

NikKelly posted at 7:11 AM Tue, 16 May 2023 - #4465478

Y-Phil, thank you for that clarification.

Whatever the reason for the 1.000 / -1.000 delay, knowing there may be a delay yet it will 'come good' makes it 'usable'...

Cool 

NikKelly posted at 7:11 AM Tue, 16 May 2023 - #4465478

Y-Phil, thank you for that clarification.

Whatever the reason for the 1.000 / -1.000 delay, knowing there may be a delay yet it will 'come good' makes it 'usable'...

Hmmm.  I'm not in front of Poser right now, but if the Mirror U/V is separate from Scale U/V, maybe part of the problem is that Poser is doing a mathematical scaling operation in addition to mirroring it? A mirror operation should be a mathematically simpler operation, simply changing a pixel's coordinates on one axis from one side to the other.    Might be an experiment worth trying.

Also, if it's an issue of refreshing the image, try turning off all of your lights and then reversing the textures.  It shouldn't take Poser long to refresh a completely black image.  Hypothetically.

Thalek posted at 5:23 PM Tue, 16 May 2023 - #4465538

NikKelly posted at 7:11 AM Tue, 16 May 2023 - #4465478

Y-Phil, thank you for that clarification.

Whatever the reason for the 1.000 / -1.000 delay, knowing there may be a delay yet it will 'come good' makes it 'usable'...

Hmmm.  I'm not in front of Poser right now, but if the Mirror U/V is separate from Scale U/V, maybe part of the problem is that Poser is doing a mathematical scaling operation in addition to mirroring it? A mirror operation should be a mathematically simpler operation, simply changing a pixel's coordinates on one axis from one side to the other.    Might be an experiment worth trying.

Also, if it's an issue of refreshing the image, try turning off all of your lights and then reversing the textures.  It shouldn't take Poser long to refresh a completely black image.  Hypothetically.

In fact, at the time of Poser12, I had written a small script to turn off all previews of all material nodes of all objects, just to speed up the material room. A few months later, Poser12 got an update that let the room react faster.

Y-Phil posted at 11:40 AM Wed, 17 May 2023 - #4465593

Thalek posted at 5:23 PM Tue, 16 May 2023 - #4465538

NikKelly posted at 7:11 AM Tue, 16 May 2023 - #4465478

Y-Phil, thank you for that clarification.

Whatever the reason for the 1.000 / -1.000 delay, knowing there may be a delay yet it will 'come good' makes it 'usable'...

Hmmm.  I'm not in front of Poser right now, but if the Mirror U/V is separate from Scale U/V, maybe part of the problem is that Poser is doing a mathematical scaling operation in addition to mirroring it? A mirror operation should be a mathematically simpler operation, simply changing a pixel's coordinates on one axis from one side to the other.    Might be an experiment worth trying.

Also, if it's an issue of refreshing the image, try turning off all of your lights and then reversing the textures.  It shouldn't take Poser long to refresh a completely black image.  Hypothetically.

In fact, at the time of Poser12, I had written a small script to turn off all previews of all material nodes of all objects, just to speed up the material room. A few months later, Poser12 got an update that let the room react faster.

[shaking head]  That appears to be a case of reverse serendipity.

Thalek posted at 8:37 PM Wed, 17 May 2023 - #4465634

In fact, at the time of Poser12, I had written a small script to turn off all previews of all material nodes of all objects, just to speed up the material room. A few months later, Poser12 got an update that let the room react faster.

[shaking head]  That appears to be a case of reverse serendipity.

In fact, I observed that too often Poser was taking its time to refresh each preview, even though if the modification was not interacting with those previews. Some optimizations are really required, even nowadays