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for this lesson we'll discuss how to
render volumetric effects like
environment fog using the GPU in v-ray
next so that you can add additional
depth than realism to your scenes while
harnessing the power of GPU rendering
first let's open the asset editor to
make sure we're on GPU and I've also
already got the denoiser on so let's
start an interactive render to get a
sense of the scene as you can see we get
a nice and quick preview of our daylight
scene here with the house and trees now
let's see how we can use the fog on GPU
to change the mood and enhance our scene
here to add the fog we can expand the
right-hand flyout menu and in the
volumetric environment settings you'll
see we have two types aerial perspective
and environment fog both types can be
used to simulate fog dust smoke or other
tiny particles floating in the
atmosphere the environment fog is more
powerful incapable of producing
volumetric shadows meanwhile the aerial
perspective calculates faster but it's
more limited in its application let's
switch to the environment fog now right
away you'll see the scene turns dark
because the fog distance parameter is
too small the distance parameter
controls the density of the fog if the
distance is increased the fog will be
thinner and we'll be able to see objects
which are further away from the camera
if the distance is reduced the fog will
be thicker and objects further away in
the scene will not be visible to make
the effect more clear let's draw a
render region and then I'm going to
increase the distance
let's try 3000 and you'll see
immediately the scene becomes much more
visible now let's try 7,000 and again
observe how the scene is more visible
because the fog becomes more transparent
with larger values we can also increase
the height of the fog since you may have
noticed that right now the fog does not
cover the entire scene let's try
something like 3000 the height controls
the real height of the fog in the scene
and as you'll see the fog has become
thicker again the
because the fog appears more dense at
the ground level and fades as it reaches
the maximum height if we compare these
three render regions the fog on the left
is too thick and also fading too close
to the ground in the middle the distance
is okay allowing us to see enough but
the height is still too small on the
right the increased height makes the fog
cover the whole scene appropriately but
overall it's too dark if we disable the
render region again you'll see that the
fog is obviously still too thick and we
are not able to see a lot one way to fix
this would be to allow for global
illumination to scatter in the fog and
add more brightness to the scene let's
draw another render region and this time
enable the scatter GI option to add
global illumination note that whichever
algorithm in your v-ray settings you
choose for example like cache will be
used to accelerate the GI inside the
volume now you'll see us this clears up
that the scene is noticeably brighter
although it's still quite foggy let's
draw another render region and this time
try setting the scatter bounces to 100
as that loads you'll see that this
increases the brightness of the light
and the fog even more note that it's the
scatter bounces are increased this
option becomes more intensive to
calculate but it can also significantly
improve the realism of your images now
comparing the three you can see that
without the GI scattering on the fog
looks a little bit fake with the scatter
bounces on the higher the number of
bounces the more precise and bright the
result will be okay let's stop the
render now and move on to discuss a few
other parameters starting a new render
again let's draw another render region
and then experiment with tinting the fog
different colors using the color swatch
parameter for example if we want to
simulate dust we can change the color to
a bright yellow experimenting with
different colors is one way to create a
variety of different moods in your
scenes
all right I'm going to disable the
render region again and now let's head
over to the lights tab to see how we can
achieve a nice dusk lighting scenario
first let's disable the sunlight and
then turn on the artificial lights here
like the garden light and v-ray IES
light now without the Sun
ring up the scene we're able to achieve
a nice desk mood we can also switch over
to the atmosphere under element where
you can see an isolated preview of how
the artificial lights are contributing
to the fog and scattering some within it
giving the scene an additional sense of
depth and realism alright I'm liking how
this is looking so let's prepare to do a
final render back in the settings tab
let's toggle off interactive rendering
so that we can do a production render
using buckets on GPU now let's start the
render
okay now looking at our final image here
you'll see that the fog is less than
some of the contrast in our image we can
easily fix this right in the v-ray frame
buffer by using various built-in
correction controls for example let's
toggle on the exposure setting and then
increase the contrast and exposure a bit
now you'll see that the trees and the
far background on the right have faded
more into the fog to create realistic
looking silhouettes in addition the
volumetric light coming from the lamp in
the garden there and elsewhere is
scattering more softly creating a nice
atmosphere all right
now you've seen how with v-ray next
support for GPU rendering of volumetric
effects like the environment fog it's
possible to get quick interactive
previews and incredibly realistic
looking production images at faster
speeds than ever before
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