Yamyam: 1版をインポートしました

2018-06-28T17:46:39Z

1版をインポートしました

wiki>Mindrones bot: Bot: Fixing redirects

2010-05-26T17:09:04Z

Bot: Fixing redirects

新規ページ

{{Page/Header|2.31|Manual/PartIV/Bump and Normal Maps|Manual/PartIV/Displacement Maps}}

[[Doc:Manual/Textures/Types/Environment Maps|A newer version of this section is available.]]

The shiny surfaces that Blender generates show specular highlights. The
ironic thing about these specular shaders, though, is that they are
sensitive only to lamps. Specifically, specular shaders surfaces show
you a bright spot as a mirror-like reflection of a lamp.
This all makes
sense except that if you turn the camera directly toward the lamp
you won't see it! The camera sees this light only if it is being
reflected by a specular shader, not directly. On the other hand, objects
that appear very bright in your scene (that reflect a lot of
light to the camera) but are not lamps don't show up in these highlights.
It is easy enough to make a lamp which is directly
visible to the camera by placing some renderable object in the scene
which looks like some appropriate sort of lamp fixture, flame, sun,
and so on. However, there is no immediate fix for the fact that
surrounding objects do not show up on specular highlights.
In a word, we lack ''reflections''. This is the sort of
problem we will
address using the technique of environment mapping.
Just as we render the light that reaches the viewing plane using
the camera to define a viewpoint, we can render the light that reaches the
surface of an object (and hence, the light that might ultimately be
reflected to the camera).
Blender's environment mapping renders a
cubic image map of the scene in the six cardinal directions from any
point. When the six tiles of the image are mapped onto an object using
the {{Literal|Refl}} input coordinates, they create the visual
complexity that the eye expects to see from shiny reflections.

{{Note|Note|
It's useful to remember here that the true goal of this technique is
''believability'', not ''accuracy''. The
eye doesn't need a
physically accurate simulation of the light's travel; it just needs to
be lulled into believing that the scene is real by seeing the complexity
it expects. The
most unbelievable thing about most rendered images is the sterility,
not the inaccuracy.
}}

The first step to follow when creating an environment map is to define the
viewpoint for the map. To begin, add an empty to the scene and place it
''in the specular position of the camera with respect to
the reflecting surface''. (This is possible, strictly speaking,
only for planar reflecting surfaces.)
Ideally, the location of the empty would mirror
the location of the camera across the plane of the polygon onto which
it is being mapped. It would be ridiculously difficult to create a
separate environment map for every polygon of a detailed mesh, so we
take advantage of the fact that the human eye is very gullible.
In particular, for relatively small and complex objects,
we can get away with simply placing the empty near the
center. We name the empty {{Literal|env}} so that we can refer to
it by name
in the environment map settings.
We will create a reflective sphere over a reflective plane, using the set
up depicted in
''Environment Map utilization example''.
[[Image:Manual-Part-IV-EnvMap01.png|frame|none|Environment Map utilization example]]
Note the 'env' Empty is placed exactly below the camera, at a distance
from the reflecting plane
equal to 3 blender units, which is equal to the height of the camera over
the same plane.
Now, let's place some lights, leave the sphere without a given
material,
and move the plane to a ''different layer''. For
example, say that everything is
on layer 1, except for the plane which is in layer 2.
Give the plane a low {{Literal|Ref}} and
{{Literal|Spec}} material
and add a texture on channel two with the parameters in ''Reflecting plane material.''.
[[Image:Manual-Part-IV-EnvMap02.png|frame|none|Reflecting plane material.]]
Note both the {{Literal|Refl}} mapping and the
{{Literal|Cmir}} effect.
We use channel 2 and not 1 because we will need channel 1 later on
in this example.
[[Image:Manual-Part-IV-EnvMap03.png|frame|none|Reflecting plane EnvMap settings.]]
Now define the newly assigned texture as an
{{Literal|EnvMap}}
in the Texture Buttons ({{shortcut|F6}}) (''Reflecting plane EnvMap settings.'').
In the {{Literal|Envmap}} Panel, note the {{Literal|Ob:}} field containing the name
of the Empty with respect to which we compute the EnvMap. Note also
the resolution of the cube on which the EnvMap will be computed and,
most important, the {{Literal|Don't render layer:}} buttons.
Because the EnvMap is computed from the Empty location it must have
an
unobstructed view of the scene. Since the reflecting plane would
completely
hide the sphere, it must be on its own layer
which must be marked as 'Not renderable' for the EnvMap calculation.
Pressing {{shortcut|F12}} starts the rendering process. First, six different
square images comprising
the EnvMap are computed, after which the final image is produced, of
the sphere reflected over the
plane.
[[Image:Manual-Part-IV-EnvMap04.png|frame|none|Sphere on a reflecting surface.]]
To add more visual appeal to the scene, add a big sphere
encompassing
the whole scene and map a sky image onto it to fake a real, cloudy
world. Then add a new Empty in the center of the Sphere and move the
Sphere
to Layer 3. Next, give the sphere an EnvMap exactly as you did for
the plane (but this time
layer 3 must not be rendered!)
Now add some cylinders, to make the environment even more
interesting,
and, before pressing {{shortcut|F12}} return to the plane's texture and press
the {{Literal|Free Data}} button. This will force Blender to
recalculate the EnvMap
for the new, different, environment.
This time in the rendering process twelve images, six for each
EnvMap, will
be computed. The result is in ''Reflecting sphere on a reflecting surface.''.
The sphere is shiner than the plane due to slightly different
settings in the materials.
[[Image:Manual-Part-IV-EnvMap05.png|frame|none|Reflecting sphere on a reflecting surface.]]
But wait, there is a problem! The Sphere reflects the Plane, but the
Plane reflects a dull grey Sphere!
This is because the Plane EnvMap is computed
''before''
the sphere EnvMap. As such, when it is computed the sphere
is still dull grey, while when the Sphere EnvMap is computed the
plane
already has its Reflection.
To fix this locate the {{Literal|Depth}} Num Button
in the {{Literal|Envmap}} panel of the Texture buttons
and set it to 1 both for the plane and the sphere EnvMap texture.
This force recursive computation of EnvMaps. Each EnvMap is
computed, then they are recomputed as many times as 'Depth' is
set to, always one after the other. The result is in
to fix this ''Reflecting sphere on a reflecting surface with multiple
reflections.''.
[[Image:Manual-Part-IV-EnvMap06.png|frame|none|Reflecting sphere on a reflecting surface with multiple
reflections.]]
Now, if you are still wondering why the first texture channel of the
Plane material
was kept empty...
Add a new texture to the first channel of the plane material.
Make it {{Literal|Glob}}, affecting the
{{Literal|Nor}}
with a 0.25 intensity (''Additional texture set-up for BumpMapping.'').
[[Image:Manual-Part-IV-EnvMap07.png|frame|none|Additional texture set-up for BumpMapping.]]
This new texture should be of {{Literal|Stucci}} type; tune
the {{Literal|Noise Size}} down to 0.15 or so.
If you now render the image the plane will look like rippled water
(''Reflecting sphere on a reflecting water with multiple
reflections.'').
[[Image:Manual-Part-IV-EnvMap08.png|frame|none|Reflecting sphere on a reflecting water with multiple
reflections.]]
You must have the BumpMap on a channel preceding the EnvMap because
textures are applied in sequence. If you were to do this the other
way around the reflection
would appear to be broken by waves.
You can save EnvMaps for later use and load them with
the pertinent buttons in the Texture Buttons. You can also
build your own envmap. The standard is to place the six
images mapped on the cube on two
rows of three images each, as in ''The EnvMap as it is stored.''.
[[Image:Manual-Part-IV-EnvMap09.png|frame|none|The EnvMap as it is stored.]]
Blender allows three types of environment maps, as you can see in ''Reflecting plane EnvMap settings.'':

*{{Literal|Static}} - The map is only calculated once during an animation or after loading a file.
*{{Literal|Anim}} - The map is calculated each time a rendering takes place. This means moving Objects are displayed correctly in mirroring surfaces.
*{{Literal|Load}} - When saved as an image file, environment maps can be loaded from disk. This option allows the fastest rendering with environment maps.

{{Note|Note|
You can animate the water of the previous example
by setting an IPO for the {{Literal|ofsX}}
and {{Literal|ofsY}} values of the texture placement
in the Material Buttons. Rendering the animation would then show
moving ripples on the surface, with reflections changing accordingly!
}}

{{Note|Note|
The EnvMap of the Plane needs to be computed only once
at the beginning if nothing else moves! Hence it can be
{{Literal|static}}.
The Envmap on the sphere is another matter, since it won't reflect
the changes in the reflections in the water unless it is computed
at each frame of the animation. Hence it should be of type
{{Literal|Anim}}.
}}

If the camera is the only moving object and you have a reflecting
plane, the Empty must move too and you must use
{{Literal|Anim}}
EnvMaps. If the object is small and the Empty is in its center, the
EnvMap can be
{{Literal|Static}}, even if the object itself rotates since
the Empty does not move. If, on the other
hand, the Object translates the Empty should follow it and the
EnvMap be
of {{Literal|Anim}} type.
Other settings are:

*{{Literal|Filter: }} - With this value you can adjust the sharpness or blurriness of the reflection.
*{{Literal|Clipsta, ClipEnd}} - These values define the clipping boundaries when rendering the environment map images.

{{Note|Note|
EnvMap calculation can be disabled at a global level by
the {{Literal|EnvMap}} Tog Button in the {{Literal|Render}}
Panel of the Rendering Buttons.
}}

{{Page/Footer|Manual/PartIV/Bump and Normal Maps|Manual/PartIV/Displacement Maps}}

← 古い版	2018年6月28日 (木) 17:46時点における版
(相違点なし)

Attic:Old/Manual/PartIV/Environment Maps 2.31 - 版の履歴

Yamyam: 1版 をインポートしました

wiki>Mindrones bot: Bot: Fixing redirects

Yamyam: 1版をインポートしました