NOW PLAYING: DISPLACEMENT AND BUMP: OVERVIEW


Fundamental Menu / 3d Texture Menu

ABOUT THIS VIDEO

In this video Paul McGrade explores bump and displacement maps. Both these types of maps affect the surface of our objects with a texture maps.  Bump maps create the illusion of bumps, divets wrinkles etc without actually changing the actual geometry.  Displacement maps change the actual geometry of an object but require more polygons and rendering time to achieve it's effect.

Running time:  2 mins 44 sec

REQUIRED CONCEPTS

Knowledge of these concepts is required: The Polygon, Texturing, UV mapping

PRESENTER
Paul McGrade is a student of animation.  He is currently enroled in Animation Mentor.

CONCEPT IN A SOFTWARE PROGRAM
image image
XSI (coming)
Maya (coming)
GLOSSARY

Bump Map: A bump map uses a greyscale texture map that creates the illusion of bumps, divets or wrinkles etc.  Black and white areas of the texture map fake an effect that causes the bumps to either penetrate or rise from the model.  Bump mapping is great for creating fine detail on models without adding to the polygon count, it's easy to paint bump maps and they are fast to render, but be careful as they don't affect the actual geometry and leave the silohette of a model unchanged.

Displacement Mapping: Displacement maps use a greyscale texture to change the geometry of an object.  Black and white areas cause the actual geometry to move up or down corresponding to their greyscale value, but the maps will only work with high or extremely high polygon counts, so they can be slow to render. These maps can be used for animating effects like an waves of an ocean or applying extreme detail to low resolution meshes that are easy to animate.


Texture Map: A 2d image, like a photo taken from a camera, or image painted in a painting program that can be projected or wrapped around a three dimesional model.  These maps can be used to affect a variety of properties of a model including color, specular, bump, displacement, reflection, ambience and much more.

Greyscale Map: An image that is made up of black and white and shades of grey.

Render: The process of calculating a 3d scene so that it draws the image.  Although this can be refered to as real time rendering as used in our 3d views or in computer games, we mostly refer to this as when we hit the render button in a 3d application and the computer takes some time, seconds, minutes or even hours to make all the calculations to display a high quality 3d image.

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rombout - Displacement maps??? | 190.2.136.xxx | 2010-03-12 00
Hi guys,
newbie here!!! whats the best method to make displacement maps off
textures. ive been searching the web for a long time but can't seem to find
almost anything.

please help
Rosver - Clarifying | 119.95.89.xxx | 2009-02-28 13
Great tutorial.

to others:
Displacement maps influence the geometry of object,
that is it deforms the object while bump maps only gives an illusion that the
object is deformed. This illusion is achieved by influencing the normals of the
face of the object when it is rendered.

Take the mapped plane in the example,
even though it has only one face, there is still dark and light areas and even
scattered highlights. This is achieved by using the bump map to define what the
normal would be at different areas of the face. This would effect the
graduations and highlights on plane. Of course this graduation and highlights
affect how you perceived the surface. Just as the Gouraud shading is used to
make your object look smooth, bump map is used to make your smooth plane look
rough. But still it just an illusion, it is not really rough and if you go look
close to the plane you would see that it is still smooth. This is evident
bec...
Lars - re: | 70.135.56.xxx | 2009-02-18 00
andrewsilke wrote:
The important thing to remember is that displacement maps take more time
than bump maps to render, that's true for all software.


True for most rendering software which uses scan-line or ray tracing, but
not necessarily for a REYES style renderer like Renderman.

(sorry
for the post above, I pushed the wrong link to reply)
Lars | 70.135.56.xxx | 2009-02-18 00
"The important thing to remember is
that displacement maps take more time
than bump maps to render, that's true for all software."

True for most
rendering software which uses scan-line or ray tracing, but not necessarily for
a REYES style renderer like Renderman.
Mark | 70.75.62.xxx | 2009-01-23 01
So Kurt your saying that you could achieve the bump in the grain of wood with a
single plane with no divisions like shown in the video, but with a displacement
map?

That's the holy grail, and sadly its impossible.
Kurt - displacement | 80.202.172.xxx | 2009-01-06 22
"the maps will only work with high or extremely high polygon
counts"

not correct. But in some apps displacement will render faster with
higher polygon count. With higher precision settings you can get the EXACT same
result with low polygon count - it just takes longer time to render.
andrewsilke | SAdministrator | 2009-01-07 00
Not sure what you mean exactly, if you are using displacement maps, at render
time the object will always need a high polygon count (depending on how far it
is from camera). Even if it doesn't seem so in the viewport, behind the scenes
the renderer will be subdividing the object to a higher poly count. Renderman
for example uses a fancy thing called "sub pixel displacement" which is
notoriously faster than other software and in it's viewport the object can be a
simple polygon hull mesh, but as I understand it is still subdividing
(subdivision surfaces) the object to a higher poly count when rendering, it just
has a very good optimization method, so renders faster than displacement in
comparable programs, mental ray for example. The important thing to remember is
that displacement maps take more time than bump maps to render, that's true for
all software.
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