How to create an exact displace map?

[phix314]

Do you know the basis behind displacement maps? White is higher, black or negative values (like in maya) are lower. Photoshop. Not sure what your question is exactly.

[logeshv]

yeah i know...the white areas will protrude out when we use a displacement map...the greys will be less protruding than the white and black remains the same...am i correcct...?

[scrimski]

yeah i know...the white areas will protrude out when we use a displacement map...the greys will be less protruding than the white and black remains the same...am i correcct...?No.
White = up, black = down, grey = remain.
However you may shift the value where the displacements remains the same.

having that said this map should be extremely easy.
You could eve use the map as it is for an displacement map. Adjustment will be mostly needed on the lower part, which you will have to darken.

[logeshv]

thanks for the reply scrimski...iam not using this texture alone...am using a mixture of 3 to 4 textures for the road...so i had doubt in the displacement maps...thanks for the info

[sundialsvc4]

If you want to achieve the effect of a slightly-curved surface, e.g. the domed profile of a roadway (and the camera's actually going to get close enough to the road to notice it...) then, perhaps only in those shots, the road could be a mesh to which a mathematical modifier has been applied, or it could be a mathematical-curve surface.

To this surface, I suspect that you could simply apply "bump" (normal...) and specularity maps, and perhaps compose the underlying surface-material of a blend of a couple of materials. You'd really only need to fool with this sort of thing for a couple of fairly-close shots.

Displacement maps effect the geometry and, as such, require a fairly high resolution of geometry, which (it seems to me...) a roadway just doesn't require.

One of the best bits of photographic advice I ever heard was, "Look at the light." In other words, nevermind what the scene "is," nevermind what you subjectively think it "looks like" ... what is the light doing right now? What are the values? What is the tonal range? That's what you need to capture in CG (or any other form of imaging ... painting, photography, whatever), and that is the only thing. But you actually have to train your eye to see it.

So ... you've got in your mind's eye this notion of "what will make a convincing road." And you might be thinking, "how do I make this road be like that." Instead, ask: "what are the five most important visual characteristics (no matter how they are produced in the bowels of the digital computer...) that say to me, 'roadway.'" Pick the best three and implement two of them, and do it as cheaply and quickly as you can manage. "Fake it." You'll be very pleased with the results.

[scrimski]

Displacement maps effect the geometry and, as such, require a fairly high resolution of geometry, which (it seems to me...) a roadway just doesn't require.They don't. Displacement maps can applied to flat surfaces with a 1 by 1 poly subdivision and still render correctly. Displacement modifiers or their equivalents require a dense geometry.

[phix314]

No.
White = up, black = down, grey = remain.
However you may shift the value where the displacements remains the same.


From my understanding of disp maps in Maya, black = remain, which is the reason one needs, for example, to change the alpha offset to a negative value to render correctly.


They don't. Displacement maps can applied to flat surfaces with a 1 by 1 poly subdivision and still render correctly. Displacement modifiers or their equivalents require a dense geometry.


What package are you using? I've never seen such a claim hold.

1x1
http://i126.photobucket.com/albums/p104/roaphotosharing/Maya/tests/noapprox.jpg

With render approximation
http://i126.photobucket.com/albums/p104/roaphotosharing/Maya/tests/approx.jpg

[bonestructure]

I have to go with sundial on this. Whenever I've needed to do a road close up, I've always put a little curve in the roadway. Very easy to do.

[logeshv]

thank you guys for ur infos...iam working on it and ill soon post a rendered image of my road and let you know how much i understood...
thanks for helping me

[soulburn3d]

They don't. Displacement maps can applied to flat surfaces with a 1 by 1 poly subdivision and still render correctly. Displacement modifiers or their equivalents require a dense geometry.

What package are you using? I've never seen such a claim hold.

This is partly correct, really it comes down to semantics. Even subpixel disp many times just dices the geometry up into lots of tiny polygons, and then moves them to the correct place. So they need dense geometry as well, it's just that they make the geometry dense themselves without the need for the user to do it. So technically you're both correct.

In practice, I have found though that's it's generally better to use a surface with at least some minor polygon density, so the disp doesn't have to do all the hard work by itself.

- Neil

[phix314]

This is partly correct, really it comes down to semantics. Even subpixel disp many times just dices the geometry up into lots of tiny polygons, and then moves them to the correct place. So they need dense geometry as well, it's just that they make the geometry dense themselves without the need for the user to do it. So technically you're both correct.

In practice, I have found though that's it's generally better to use a surface with at least some minor polygon density, so the disp doesn't have to do all the hard work by itself.

- Neil

Interesting. I've never come across this, so thanks for clearing that up :)

[rdane1010]

Check out Genetica (google it) as they have a free viewer that can generate some decent heigh maps (displacement), also crazybump can grab height maps from photos... other than that you can create pieces of 3d geometry and render them in such a way that it can produce a height map (depends on which software you are using).. then you can tile the map however you like or arrange the pieces differently in a 2d program.

[logeshv]

now i have a new doubt....:rolleyes:
is it good to use third party map generators like crazy bump or genetica or shader map pro ..? or is it good to do it by ourselves in photoshop? which will give the best result and also which method wil have more control ???

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