Do I Understand Displacement Maps?

Inkubo

Here's how I think displacement maps work in DAZ Studio:

• Black (RGB 0,0,0) is low. If your minimum displacement setting is left at the default of 0, then black = no displacement
• White (RGB 255,255,255) is high. It will be translated to whatever is the maximum displacement setting you select in the Surfaces tab
• Shades of gray map proportionally between the minimum and maximum displacement

I wanted to draw veins on a character's skin, so I filled a .jpg with black and used a soft white brush to draw the veins. The result looks great, except that when the displacement map is used, seams pop out between this section of skin and others that don't have displacement maps. Light reflects off the surface's edges as if there is a slightly raised area there.

The fact that it isn't seamless suggests I'm doing something wrong. Have I misunderstood how displacement maps are supposed to work?

WendyLuvsCatz

in DAZ studio I believe zero is a neutral grey as it has positive and negative displacement

it varies between apps

in many other apps indeed black is zero but not in D|S

Chohole

mid grey is flat.  Black recedes, goes down  White goes up       for biological features made using displacement you need a smooth transition through the shades to give the soft edge  

Richard Haseltine

The default minimum is not 0, that's the issue. other than that you are correct - and mid-grey is the mid-point between the two extremes, it's neutral only if they are of the same magnitude and opposite sign.

gederix

Rather than filling the layer with 100 black you want to use 50black. In photoshop one way is to switch to the HSB color sliders and go 0 0 50.

(PS additional tip: The HSB 0 0 50 layer is also a handy trick for using the burn/dodge tool without permanently affecting the image. Which among other things is useful for hand-painting liquids).

Displacement map seams is a whole other issue, personally I avoid them on people for that very reason.

jestmart

Black is 0 and white is 1 and all the greys in between.  Use a 16 bit or 32 bit grey-scale format to have more 'in betweens' and  smoother displacement.

 

Richard Haseltine

gederix said:

Rather than filling the layer with 100 black you want to use 50black. In photoshop one way is to switch to the HSB color sliders and go 0 0 50.

(PS additional tip: The HSB 0 0 50 layer is also a handy trick for using the burn/dodge tool without permanently affecting the image. Which among other things is useful for hand-painting liquids).

Displacement map seams is a whole other issue, personally I avoid them on people for that very reason.

This wastes half of the value range - use black as the base and set the minimum value to 0 should work.

Inkubo

Thank you all.

Richard, do you therefore believe that DS would handle displacement so that if skin part A has no displacement map and skin part B has a minimum displacement of exactly zero and a higher maximum and a displacement map that's black where the skin parts meet, then there should be no visible displacement seam?

That was a complex sentence, so I'm going to restate the same thing in a different way:

• Skin Part A: Displacement Map = None, Strength = 0
• Skin Part B: Displacement Map = Mostly black jpg with smoothly graded white veins in places where no skin parts should meet, Strength = 1, Minimum = 0, Maximum = 1 or 3 or whatever.

I drew in black and white, but didn't do anything to ask GIMP to convert my map to grayscale, so maybe that's my problem...

gederix

Richard Haseltine said:

gederix said:

Rather than filling the layer with 100 black you want to use 50black. In photoshop one way is to switch to the HSB color sliders and go 0 0 50.

(PS additional tip: The HSB 0 0 50 layer is also a handy trick for using the burn/dodge tool without permanently affecting the image. Which among other things is useful for hand-painting liquids).

Displacement map seams is a whole other issue, personally I avoid them on people for that very reason.

This wastes half of the value range - use black as the base and set the minimum value to 0 should work.

I guess I misunderstood what you were saying. Still dont actually. If what Chohole said is correct my method should work and would use the whole range. Paint whites for heights and blacks for depths on a 50grey surface.

 

kitakoredaz

when I tested before which value is newtral for DS iray, with displacement map, actually gley (in gimp  H value = 50)

was perfect newtral as default setting,,  (need to gamma setting correctly = 1.0)

and when displace ment map = newtral grey,  and Min and max  Absolute values are equal ( min -1 max 1, or min -2 max 2)

even though I change strength to 2.00 (default limit) , the surface not move. I can confrim compare with no displacement map surface. 

But,, iray displacement offer min and max value,  it change newtral color.  

if I set min =0,  and max =1, newtral grey = 0.5.. then surface up.

if I set min =-1  and max =0 newtral grey means = - 0.5  then surface down. (min value + max value) /2 

if I set min = -2,  and max = 1  newtral grey = -0.5, then surface down.. then   displace ment strength will be multipled. 

apply strength zero value have no meanig. no displacement.

then apply black map = surface down, with strength value (multiple) (when min and max absolute value equal)

then apply white map = surface up, with strength value (mutlitple)

then, Inkubo said, skin part A = perfect flat (if you strength = 0, this value will be multiple then, which strength map you used, there is no meaning, without DS shader corrupt)

skin part B = mostly black with strength 1 (I assume maybe daz unit) , 1cm down.  newtral grey part = flat. 

 

kitakoredaz

Then I do not against anyone, but most of PBR shader or 3d Paint may use grey as newtral. then produce displacement map so.

I usually first color back as 0.5, then make brush, or displacement map.

dark value,  0.5  to  0  use concave , 0.5 to 1 use for convex.  then sculpt. or if I export displacement map, it generate newtral as grey (0.5).   then I prefer to keep grey as background color and it is flat color.  with keep, min and max as default. then just keep same absolute values, (min and max).

usually min value just use to adjust off set. without it, I can not concave.

Though I understand,,  Richad suppose, inkubo only need Convex, then suggest to use full 0(black)  to 1 (white)  range for convex. (then set min 0, max 1up).

Richard Haseltine

Inkubo said:

Thank you all.

Richard, do you therefore believe that DS would handle displacement so that if skin part A has no displacement map and skin part B has a minimum displacement of exactly zero and a higher maximum and a displacement map that's black where the skin parts meet, then there should be no visible displacement seam?

That was a complex sentence, so I'm going to restate the same thing in a different way:

• Skin Part A: Displacement Map = None, Strength = 0
• Skin Part B: Displacement Map = Mostly black jpg with smoothly graded white veins in places where no skin parts should meet, Strength = 1, Minimum = 0, Maximum = 1 or 3 or whatever.

I drew in black and white, but didn't do anything to ask GIMP to convert my map to grayscale, so maybe that's my problem...

Those values should work, yes - though I think Iray does expect greyscale maps, not colour maps with equal values in each channel.