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Poser F.A.Q (Updated: 2018 Dec 12 9:55 am)


 Subject: Question about displacement

smalll opened this issue on Jan 05, 2009 · 52 posts

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  smalll    ( ) ( posted at 7:21PM Mon, 05 January 2009 

Hi.
I need your help.
I'm studying poser now.
And I applied displacement map in material room.
But, there is no effect.
Could you tell me what proublem is it?
Model is Prop > primitives > HiRes ball
Texture is New Node > 3D Textures > spots
Please
help me.

 

(I used poser pro)


  FrankT    ( ) ( posted at 7:28PM Mon, 05 January 2009  · @3362413

have you turned on "use displacement" in the render settings ?

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  smalll    ( ) ( posted at 7:35PM Mon, 05 January 2009  · @3362420

No.
I'll see now.
I'm sorry about my foolish.
Thanks to FrankT.
You give me great help.
 


  Miss Nancy    ( ) ( posted at 9:26PM Mon, 05 January 2009  · @3362468

하나를 사용해야합니다, 회색, 검정과 변위에 대한 백인.
레드 화이트와 같은 변위 값을 갖습니다.



  smalll    ( ) ( posted at 9:36PM Mon, 05 January 2009  · @3362471

Thanks to Miss Nancy.
You are so kind.
Fantastic! Amazing!
Thanks!


  hborre    ( ) ( posted at 10:38PM Mon, 05 January 2009  · @3362485

Also check your Display Units under General Preferences.  If your scale is set to meters, the displacement will become very exaggerated and distorted.


  smalll    ( ) ( posted at 2:08AM Tue, 06 January 2009  · @3362526

Thanks to hborre.
 I thank you from the bottom of my heart.


  IsaoShi    ( ) ( posted at 6:36AM Tue, 06 January 2009 · edited on 6:40AM Tue, 06 January 2009 · @3362596

Hi smalll...

Where there is black in a displacement map, it gives zero displacement, and white gives maximum displacement, as determined by the value on the Poser Surface node. (I think I have this the right way round - someone please correct me if I am wrong).

Displacement uses a single (greyscale) value, so your bright red (RGB value 127,0,0) would give one-third of your maximum displacement.

So if you use red as the base colour for the Spots node you are applying one-third of your  maximum displacement value over those parts of the surface, and maximum displacement where the white is.

You might get some weird effects from this, so it's probably better to start with black as the base colour, and white to give the required displacement.

Izi

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)

  Gareee    ( ) ( posted at 8:14AM Tue, 06 January 2009  · @3362645

Actaully, middle gray is the base non displaced color. Black (or darker) displaces inward, and white displaces outward.

Way too many people take way too many things way too seriously.

  IsaoShi    ( ) ( posted at 8:51AM Tue, 06 January 2009  · @3362662

Oh.. thanks for the correction Gareee. I was wondering about negative displacement as I typed. I should have wondered a bit further.

In that case, by my calculation smalll's full red in her displacement map would give an inward displacement of one-third of the maximum.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)

  bagginsbill    ( ) ( posted at 4:11PM Tue, 06 January 2009 · edited on 4:12PM Tue, 06 January 2009 · @3362917

Quote - Actaully, middle gray is the base non displaced color. Black (or darker) displaces inward, and white displaces outward.

NOOOOOOO!

That is other programs. In Poser, black = 0. To produce no displacement, you send a ZERO to the displacment channel.

I have written about this many times. I wrote an extensive thread with many pictures - don't know where that is now.

Red 255 would produce 1/3 displacement. Red 127 would produce 1/6 displacement.

To produce negative displacement, you must send a negative number. THESE ARE NOT COLORS PEOPLE. They are numbers. It just so happens you can "see" numbers between 0 and 1 as gray scale, but you limit your thinking (in fact you muddle your thinking) by insisting that the data is a gray scale image. It is not an image. It is a two-dimensional array of numbers.


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  IsaoShi    ( ) ( posted at 4:22PM Tue, 06 January 2009  · @3362923

Completely unmuddled now... thanks bb.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)

  bagginsbill    ( ) ( posted at 4:25PM Tue, 06 January 2009 · edited on 4:27PM Tue, 06 January 2009 · @3362925

Attached Link: Masking into the Dissplacement Node?

Found the thread - follow the link

If you want Poser to behave like other programs, where gray (.5) is neutral, black (0) is inward (negative displacement), and white (1) is outward (postiive displacement), you must subtract .5 from the data.


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  Gareee    ( ) ( posted at 4:27PM Tue, 06 January 2009 · edited on 4:35PM Tue, 06 January 2009 · @3362926


I was referring to how it looks to the eye.

Here's my warcow displacement map, for example.

And yeah I did use the math node as well. since you have to get the displacement map out of a program like zbrush or mudbox, we have to get things like that to work in poser itself. I can't imagine trying to say, paint a displacement maps for a figure in a 2d program.

Way too many people take way too many things way too seriously.

  bagginsbill    ( ) ( posted at 5:15PM Tue, 06 January 2009  · @3362947


Quote - I was referring to how it looks to the eye.

: GRIN :

Click for full size.

If your "field", i.e. the majority of your displacement map, is white, than anything less than white, including "neutral gray" looks like a negative displacement.

I would accept the notion that you think of black as an indentation, when used against a non-black field. But it is very confusing to people if you tell them that gray causes no displacement. It is really important that people understand this. It is why you get bloat on a figure when you plug a gray-neutral displacement map into a Poser figure. It's fine to say you intend the black area to be a negative displacement, or and indentation of the field, but to actually say that black is or causes a negative displacement is incorrect, and many Poser users get very confused by the strange behavior they end up with.


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  bagginsbill    ( ) ( posted at 5:17PM Tue, 06 January 2009  · @3362950

Quote - we have to get things like that to work in poser itself

If you plug that straight into your figure, you will get bloat. If you intended the gray field to be neutral, and you did not subtract .5 from that, you messed up.


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  bagginsbill    ( ) ( posted at 5:25PM Tue, 06 January 2009  · @3362953


Oooh - it's even worse with your warcow displacement map.

Your neutral field value is RGB 149. Which means even subtracting .5 doesn't work with that map. For that one, you must subtract 149/255.

Here is your warcow map applied to M4's torso. Notice how all of the torso, even the "neutral" parts are displaced and separated from the rest of the figure.


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  bagginsbill    ( ) ( posted at 5:26PM Tue, 06 January 2009  · @3362955


This time, I subtracted 149/255 from your map value, because the neutral field on YOUR map is neither black nor mid-gray, but RGB 149, 149, 149.

Now the shoulder area is un-displaced like it's supposed to be with that map.


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  bopperthijs    ( ) ( posted at 6:01PM Tue, 06 January 2009 · edited on 6:01PM Tue, 06 January 2009 · @3362979

@ Baggingsbill,

Do you know if poser accept 16bit greyscale  files, like tiff-files or does it convert back to 8bit bitmaps?

I've tried it to make a smoother displacement because when you use a big displacementscale you actually see steps, but as a matter of fact I didn't see much difference.

Thanks,

Bopper.

-How can you improve things when you don't make mistakes?


  smalll    ( ) ( posted at 7:01PM Tue, 06 January 2009  · @3363006

I can never thank you enough.
I have no words to express my gratitude.
I can´t find the words to thank you.
It's amazing!


  Gareee    ( ) ( posted at 7:17PM Tue, 06 January 2009  · @3363015

That wasn't the exact map, BB.. I scaled it down, sharpened it, and kicked up the contrast on it to make it a bit more visible what was going on, but with a smaller image size.. ;)

But year, peopel do need to know not only how poser handles it, but also how to use exported displacement maps from zbrush, Mudbox, hexagon, or  anything else that exports displacement maps.

I don't actually think anyone has compared them, or included how they need to be used in thier various aspects anywhere though.

Way too many people take way too many things way too seriously.

  bagginsbill    ( ) ( posted at 9:29PM Tue, 06 January 2009  · @3363088

Quote - Do you know if poser accept 16bit greyscale  files, like tiff-files or does it convert back to 8bit bitmaps?

 
Yes Poser 7 does support 16-bit precision TIFF files for displacement. The original Poser 7 had a bug in it where it misbehaved by always reading a 1 value in the blue channel of the TIFF, but I reported that bug and they fixed it.

There was quite a long thread about that here, where I gave a way to ignore the bad data from the blue channel. We don't need to worry about that any more, but the thread is still interesting to read.

It's here at runtimedna

http://www.runtimedna.com/mod/forum/messages.php?ShowMessage=386252


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  bagginsbill    ( ) ( posted at 9:39PM Tue, 06 January 2009  · @3363092

LOL I totally forget who I talk to and about what. Gareee, in that thread I linked to about the blue-channel bug and displacement, you were talking about warcow bloat!

The last shader you posted there had the bloat because you used the Comp node to extract only one channel, but you didn't also subtract .5 there.


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  giorgio_2004    ( ) ( posted at 5:25AM Wed, 07 January 2009  · @3363227

@bagginsbill:

Now I have finally understood how displacement works. Thank you very much!

But what about Bump channel? Does it work like displacement or in the "traditional" way, that is, 50% gray means "no change" while white/black are positive/negative elevations?

Giorgio

giorgio_2004 here, ksabers on XBox Live, PSN  and everywhere else.


  Gareee    ( ) ( posted at 8:26AM Wed, 07 January 2009  · @3363274

Yeah BB.. I figured you'd recall that sooner or later.. LOL!

It'd be nice if doisplacement paint programs like zbrush just had some default settings you could choose for output maps, like poser, vue, lightwave, ect, to put out the best displacement map for how the target application actually wants it.

It's just hell to learn for a beginner, or even someone expereinced just looking into it.

Way too many people take way too many things way too seriously.

  smalll    ( ) ( posted at 8:51AM Wed, 07 January 2009  · @3363280

Thank you all of you!
It was great help to me.
You are so kind!


  bagginsbill    ( ) ( posted at 9:03AM Wed, 07 January 2009  · @3363284

Quote - But what about Bump channel? Does it work like displacement or in the "traditional" way, that is, 50% gray means "no change" while white/black are positive/negative elevations?

Great question. Bump works the same way, which means that everybody for all of Poser history has been using bump maps incorrectly. However, almost nobody believes me. Mostly this is because the nature of bump mapping often does not reveal a problem. The surface doesn't actually move, so you don't see the "bloat".

But, if you have two surfaces opposed to each other very close together, the virtual bloat becomes evident. Bump mapping does not actually move the surface, but it does calculate things as if it did move it, then retains the changes in surface normal. As a result, if you have two surfaces very close together and facing each other, if you bump them past each other, you will get virtual crossover, and the render will have an artifact.

Most bump maps have sufficient dynamic range (difference between highest and lowest points) that people are able to use a very small bump value as a multiplier. So the overall field value, which is usually .5, does not appear to cause a bloat artifact.

However, if you have a very low dynamic range bump map, i.e. one that is almost entirely mid gray, then you will need to crank up the bump value. This means, for example, that if you have the bump value at .5 inch, and your field is .5, then you are performing an overall virtual displacement of .25 inch.

I will now demonstrate this problem to you, using the lo-res textures that come with M4.


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  bagginsbill    ( ) ( posted at 9:06AM Wed, 07 January 2009  · @3363285


Here is a very simple shader for M4, using the color map, but not the bump map yet.

Look at the bump map - it is almost entirely mid-gray, or .5. The variations are tiny.

(Note that this is a terrible bump map - practically useless in fact. But I find it useful here to demonstrate the bump bloat problem.)

In this image, I show you the shader and the render.


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  Gareee    ( ) ( posted at 9:06AM Wed, 07 January 2009  · @3363287

BB, while we are on (sort of) the subject, have you ever found any evidence that using the new poser pro normal mapping is any better then displacement?

Way too many people take way too many things way too seriously.

  bagginsbill    ( ) ( posted at 9:08AM Wed, 07 January 2009  · @3363289


Now I attach the bump map the way everybody (but me) does it.

I have to increase the bump amount to .2 to even be able to see the bump at all. (Again, this is a terrible bump map - too low resolution, no dynamic range, and just bad shapes in general. But whatever.)

Look at the render. Wherever there are two surfaces in close proximity, opposite in orientation (facing each other) we see a rendering artifact. These are in the eyelid creases, the nostril crease, and the corner of the mouth.

If you fail to understand the bloating, you might think that decreasing the bump value would solve the problem. And it would, but you'd also cause the bump map to have almost no visible effect. So decreasing the bump value is not the right approach.


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  bagginsbill    ( ) ( posted at 9:11AM Wed, 07 January 2009  · @3363293


Here is the correct solution - identical to how you should handle displacement maps.

You must subtract the "field value" from the image value. In this case, the field is .5, so I subtract .5. This means that across the image, the mid-gray field yields a numerical value of 0 which means no change across most of the surface.

Only where the value is slightly more than .5 or slightly less than .5 do we get a peak or valley on the surface.

This is the correct way to handle mid-gray field bump maps and displacement maps. Again, we almost never see this problem, so it is safe to ignore 90% of the time. But why take the risk? Also, even if you have a pretty good bump map with nice dynamic range, you are still getting a small difference in the rendered output. If you load a good bump map, zoom in close and render with and without the .5 offset. You will often see a difference. It is usually not a difference you would notice unless you do a direct comparison, but it is there nonetheless.


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