I'm currently messing around with displacement maps, making them in ZBrush and rendering them in Poser 10.  It has me wondering, is there a recognised general intensity in Poser that vendors stick to?

I realise the intensity can be sat at will, but should I be aiming for a certain intensity on export of the map from ZBrush so that it looks right at a certain intensity that is, like I said, a recognised default in Poser?

displacement in poser is function of user's units in prefs.

Keep in mind that Poser interpretes displacement in a peculiar way. Black is no displacement. In many other programs black is negeative displacement and medium grey is no displacement. I don't know how ZBruse uses disp maps so you need to check what conventions it uses. If it considers medium grey "no displacement" then you have some conversion to do.

Cheers.

@MissNancy
Ah, never knew that!

And that creates a different issue then; like how do vendors go about ensuring that when a user applies a material preset, the displacement will have the correct amplitude?

@Paolo
ZBrush has a function called "Mid" in the Displacement Map panel, I think that's what you're getting at.  It's a slider which lets you set the mid-point of the displacement amplitude.  It's at 0.5 by default meaning that mid-grey equals no displacement, but it can be adjusted by sliding the control between 0 and 1.

At least I think that's how it works, I'm only just getting into displacement :-P

Quote - And that creates a different issue then; like how do vendors go about ensuring that when a user applies a material preset, the displacement will have the correct amplitude?

You've become misinformed. The displacement amount in the file is the same no matter what you're seeing on the screen. The display of that amount will depend on your chosen units, but that's a display unit, not a rendering unit. The rendering unit (what is in the file) is a constant, and it is inches.

Since people copy my shaders from screen shots, it is why I say in my signature:

My Poser Display Units are Inches.

If, however, I give you an actual mt5 material file, you don't need to know my display units and whatever I've set up will display on your screen in your units.

Quote - ZBrush has a function called "Mid" in the Displacement Map panel, I think that's what you're getting at.  It's a slider which lets you set the mid-point of the displacement amplitude.  It's at 0.5 by default meaning that mid-grey equals no displacement, but it can be adjusted by sliding the control between 0 and 1.

And Poser has a math:subtract node that can make the midpoint 0, .5, .7571575, 1, 2014, or any other number you want. However, if you intend to just plug the displacement in straight without an offset (via math node) then configure ZBrush to use 0. You will be unable to represent a negative displacement in that case.

Quote - I'm currently messing around with displacement maps, making them in ZBrush and rendering them in Poser 10.  It has me wondering, is there a recognised general intensity in Poser that vendors stick to?

Not that I'm aware of. The fact is that if your d-map is 8 bits per pixel, then you only have 256 levels at best for your fine-grained steps. It follows that for maximum fidelity, you want your lowest point to be black (0) and your highest point to be white (255). If the range of heights is squished into something smaller than 256 steps, you're going to get a bigger jump from one value to another. This may or may not matter, but I have seen terraces formed by not using enough range.

Given that the range from low to high will depend on the context, it becomes obvious that the best standard is no standard at all. You want to use the maximum range of the d-map to get the best (most smooth, stair-step-free) pattern you can. If that range spans 8 feet, then so be it. If it spans 2 mm, then so be it.

Read these

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2943106

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2949082

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=2950918&ebot_calc_page#message_2950918

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2626388

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2759991

I'm a bit confused regards what you said about the math node so I tried it they way I've been doing it.  I just drive the Displacement directly from a 2D Image Node and it works, it gives me both positive and negative displacement even without a math node, and with ZBrush displacement set to 0.5.

I've pulled everything into one screenshot to show you what I mean.  Note that although the"Mid" control is greyed-out now in ZBrush, it actually is set to 0.5, it's just that 0.5 isn't half way along the slider.  But yup, didn't need to do anything fancy, all I did was a quick low-res displacement, flipped it vertically and exported it with the "Mid" slider set to 0.5.

In Poser, it just drives the Displacement directly, no math node needed, I just set to 0.007500 out of preference.

@Paolo
Just in case you're curious what displacement controls ZBrush has, check-out the basic Displacement Panel that's open in this screenshot.  There's another Displacement panel as well, for "Vector Displacement" but I've not even looked into that one yet - I don't think I need it.

You would need to check where the edge of the displacement map is on the figure.

 If you are using a setting which represents no displacement as black, with a map which is designed for no displacement at mid grey, then you will get a step at the edge of your displacement map because the whole area of the model covered by the map is being displaced 50%. In the middle of the map, such as the forehead, it will look 'right' beause you have zero displacement/50% displacerment/ full displacement. 

Just a heads up to you, though it will increase file size quite a bit, Poser accepts 16 bit TIF images as displacement maps. So save out to that if possible.

What I usually do for determining intensity level is I look at the Displacement Map menu in the ZBrush Tool menu for the intensity. In my case, it's usually 0.00x (where x is a serious of numbers). I jot down the numbers and then input those into Poser's displacement intensity. Sometimes I have to cut it by half or sometimes I just need to move the decimal point a bit but usually those numbers work or make for a good starting place (note that they change for each displacement map you make in ZB).  

At the moment Poser doesn't support vector displacement.

**
@IanPorter**
Ah, it's when lining it up against something that doesn't have displacement that the problem would show more, it would only be fine if everything connecting had a displacement map with the same setting.  Got ya.  I still get a joint though, only less noticable, no doubt 50% less displacement from the neighbouring mesh instead of 100%.  The math node still seems pointless if using it still gives a joint though, I just don't get that part.

@Teyon
I had no idea it even gave a readout until I moused over it, and it does look about right if I feed those numbers into Poser's Displacement value.  I'm pleased I asked about this now, bloody hell, that's three major things regards displacement I hadn't even thought about.

It's been a real education, thanks all.  I'll just have to play around with what I've read and learnt and see what else clicks!

Hi,

Using the math node, as BB suggests would shift the displacement map values, so that 50% displacement ( mid grey ) becomes zero displaceemnt. So using that you would get no step at the edge of the map. Your black and white areas on the map would produce negative and positive displacement.

That's what I thought he meant, but I still do get a step using the math node!

Actually I think it's just me misinterpreting what to expect.

Math node or no math node, putting the displaced part of the map is always going to create a step when butted up to a mesh that doens't have one.  When I use the math node I only get the step at displaced parts of the map, so yup, I get it now.

For some reason I had it in my head that using the math node would somehow blend everything - duh!

Quote - Math node or no math node, putting the displaced part of the map is always going to create a step when butted up to a mesh that doens't have one.

No. If you had read the several threads I linked to you would see my exact demonstration that the it is possible for a displacement to have no actual movement from the original position, which would make it possible to match an undisplaced surface.

What I think you're laboring under is:

1. We say .5 but we don't mean it. We mean 128/255 or 127/255, neither of which is precisely .5, which is halfway between those two. If you want to match the neutral displacement field value exactly with zero movement, you have to look at what that value is, and use the exact number that represents that color. 127/255 is 0.49803921568. 128/255 is 0.50196078431. In one of the linked threads, a person had posted a displacement map with the neutral field color at 149, so his neutral offset should have been 0.58431372549.

or

1. You have render gamma turned on and you forgot to set the displacement map gamma to 1. If you leave the default it will be applying gamma to the map and shifting the neutral field value down to 0.21951971807, creating a very obvious step when you misinterpret that as .5. Set the image gamma on all maps to 1 except for actual color maps.

I really think you should read the threads I linked to. All of the questions or confusions brought up in this thread were explictly addressed in them. You either didn't read them, or you read them too fast to notice they were talking to you.

Note: The last point should be this - if the edge of the displacement-affected area is not set to your neutral field value, then you will have a step there. You can't match up multiple, different edge values - they can't all be 0. Only one value becomes 0. If that's what you meant (that a uniform, zero displacement can't exist at the edge unless all the edge values are the same), well that's true.

Quote - I just drive the Displacement directly from a 2D Image Node and it works, it gives me both positive and negative displacement even without a math node

This is classic misdirection of the self. You demonstrated visual relativity.

Clear your mind of assumptions, close your eyes and imagine the following. (After you read it first, of course)

You are in a temple with magical floor tiles that can move up, but not down, from their natural position. You figure out the magical controls and you raise all the tiles in the temple up two feet, except for the center tile. The center tile you only raise up one foot.

Now you photograph this and you show others that you have moved a subset of the tiles and ask them to tell you which tile(s) were moved and in what direction. Who among them would not tell you that you lowered the middle tile? Yet, in fact, you raised that one and all the others as well.

This image from one of the linked threads demonstrates that all values but 0 are actually "outward". This is the magical tile demonstration made real.

And this demonstrates that the offset will shove the whole thing back into neutral position, with only the white and black areas actually moved from original position.

In the latter image, there is, in fact, still a step, because I used .5, not 128/255 (or 127, whichever it should be - I didn't measure it). But it's really small.

Cheers baggins' and yup, I read it apart from two of them before I posted my demonstration, but I've read the lot now :-)

You might have missed my previous post while you were preparing those last posts, but I get it now.  The images in your post above demonstrate to me how the offset works, but what's missing in those images (the bit that confused me about the need for a math node) is any displacement along the edge of the square.

In other words, I still thought I was seeing a gap because I had a head with displacement right next to a neck without it.  Even with the math node this created a very fine edge where the little pits of the skin were on the head but not the neck.  The pits cover the skin right to the edge of the map whereas the displaced text in the demo above doesn't show that aspect of it.

As for Gamma, thanks for pointing that out, that's another thing I never thought about!

is it possible to like, generate random greebles displacement for space ships and such?

random math or python script maybe?

Thanks.

Haven't tried it but I don't see why not.

I suppose multiple chequered and striped nodes with different scales and amplitudes would do it if they were mixed and fed into the dispacement node.