Forum: Poser - OFFICIAL

Subject: Having A Problem with Displacement

Latexluv opened this issue on Jan 10, 2009 · 16 posts

Latexluv posted Sat, 10 January 2009 at 4:27 AM

I am working on some water shaders and I am having  trouble every time that I use displacement for waves or ripples. I've had to switch to using bump and gradient bump instead. I've rendered two examples. The first is a wavy shader using displacement. The second is when I switched to using bump and gradient bump. Can someone tell me why this is happening?

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Latexluv posted Sat, 10 January 2009 at 4:29 AM

And the second image.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

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SAMS3D posted Sat, 10 January 2009 at 4:41 AM

hmmm, not sure, but your water really looks nice.  Sharen

Latexluv posted Sat, 10 January 2009 at 5:14 AM

Thank you very much! I just wish I knew what was up with displacement.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

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hborre posted Sat, 10 January 2009 at 6:35 AM

There seems to be too much turbulence for your bath tub water.  It indicates that your displacement values are set too high.  Try reducing your values or check your display units in General Preferences.  It should be set to inches.

nruddock posted Sat, 10 January 2009 at 6:43 AM

What exactly is it that you think is wrong with the displacement in the first image ?

IsaoShi posted Sat, 10 January 2009 at 6:54 AM

Please post a screenshot of your shader setup for this, with the displacement map image visible.

As hborre says above, but also...

It might be suffering from displacement bloat, caused by an inadvertent misuse of the displacement map within Poser. Basically, if the displacement map has a base value of around mid-grey and it is plugged directly into the displacement socket on the Poser surface, it will be wrong. You have to subtract the base colour before plugging it in, using a math subtract node with a value of the base colour of the displacement map.

There is a thread about this, with explanation by bagginsbill, which I will post a link to if I can find it again.

If the base shade of your displacement map is black, you can ignore all this.

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adp001 posted Sat, 10 January 2009 at 7:28 AM

I think there is nothing wrong with the displacement.
In my opinion it's just a lighteffect. With a displacementmap your light has another angle to the watersurface than if you use a simple ("flat") bumpmap.


Latexluv posted Sat, 10 January 2009 at 5:01 PM

Thanks for the assist! I had thought that my preferences was in inches but it was in feet. I changed that back to inches and reset my preferences. However this did not fix the problem when I rendered a test image. So, I've done a screen cap of my displacement settings. Any help would be appreciated. I only returned from the Xmas/New Years holiday at the family thing a couple of days ago so I'm not sure what displacement discussion you are reccommending. I love it anytime Bagginsbill imparts of his Poser knowledge, however, I'm not always able to follow him. HIs command of math is far beyond mine.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

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Miss Nancy posted Sat, 10 January 2009 at 5:29 PM

one thing I noticed was that specular was (white, 1), but alternate specular was also non-zero.


Latexluv posted Sat, 10 January 2009 at 7:02 PM

As an experiment, I used a water shader by Ajax which also uses displacement and it is rendering in the same way.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

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Poser Pro 2012, SR2, Paintshop Pro 8

 

 

bagginsbill posted Sun, 11 January 2009 at 11:25 AM

You have mis-used the Fresnel node. First of all you plugged it into Reflection_Color and Refraction_Color. This means you are adding up multiples of the node. You kept your nodes closed so I can't see what else is going on. But it wrong to use Edge_Blend with the Fresnel. The Fresnel node already has Edge_Blend + some math, Reflection, and Refrection all built into it. You should not be doing anything with it like you would for those nodes hand-assembled. Just plug it into Reflection_Color or Refraction_Color or Alternate_whatever - just don't plug it in multiple times.

It is also wrong to use anisotropic with water - not at all what you want. Use the Glossy alone, or a Blinn with Eccentricity very low, like .01, and Specular Falloff something like .2 to .4.

Having said all that, I'm not sure what whether that has anything to do with the darkening. Perhaps the Fresnel node is at fault. I've seen it misbehave before.

In which case you may want to try manually assembling Reflect+Refract, etc.

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bagginsbill posted Sun, 11 January 2009 at 11:34 AM

Quote - I changed that back to inches and reset my preferences. However this did not fix the problem when I rendered a test image.

FYI, changing your preferences does not alter the values in your shaders. It alters how they are DISPLAYED as numbers. They are what they are regardless of your display units.

Your PDU will influence how we see and enter these numbers ONLY.

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)

bagginsbill posted Sun, 11 January 2009 at 4:04 PM

I'm wondering if you have your water plane casting a shadow - it shouldn't.

I can't reproduce the problem you're having with the darker water when using displacement.

What version of Poser? What SR?

I made this using Fresnel node only, plugging into Alt_Diffuse. I used the same fBm as you showed in your shader, but I reduced the displacement amount to .1 inch. Water is a lot flatter than most people think. A* big* bathtub wave is .25 inches.

The fBm set you used has very small range (no black or white - just all near mid gray) so of course if we dial in .1 inch, we aren't getting anywhere near that.

But you have nearly an inch dialed in - that's too much. Even if the fBm range is only a quarter that, you still are dealing with HUGE bathtub waves.

In my render, every surface has a Fresnel effect applied, but only the water was done with a Fresnel node, since only the water has refraction in it.

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)

Latexluv posted Sun, 11 January 2009 at 6:24 PM

I am using a premade bathroom from Poserworld. I just checked the bath tub's water plane and shadows were on, so I just turned them off. I've followed your instructions and reworked the setup. I find that the displacement problem goes away as long as displacement is something like .09. If I go to .1, I get what I call 'artifacts' in the water, or 'fuzzy' spots. I'm re-rendering my image now. Will take a few minutes.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8

 

 

Latexluv posted Sun, 11 January 2009 at 6:38 PM

Okay, turning off shadows on the water plane in the bath tub did wonders. I had not checked this option when loading up the bathroom props.

Oh, and I'm rendering in Poser Pro. I think I have installed the latest serial update for it. I use Poser Pro mostly as a render engine. Almost all my content is loaded into Poser 7, Poser 5, and Poser 4 which I have installed in an external hard drive.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8