Blender 2.7 Tutorial #70: Speeding Up Cycles & GPU Rendering with CUDA #b3d Video Lecture | Learn and Master: Blender (English) - Professional Skills

welcome to part 70 levity season I use
blender 2.7 in this video we're talking
about render speeds using the cycles
render engine now it's no secret that
you can get amazing looking results
using the cycles render engine in
blender but it's also no secure that I
can take a long long time to render so
in this video I'm going to be showing
you several ways several settings over
here in the properties window
that you can change including using GPU
CUDA rendering we'll get to that later
in the video so your renders will take a
lot less time to render each frame which
will amount to a lot of time saved
especially if you're rendering out
entire animation with lots of frames if
you want to follow along with me you can
download the exact file that I have on
my screen right now in the description
area below and this file has a bunch of
assortment of objects just sitting on a
round ground and if I break out of my
camera view you can see that I have
three area lamps around my scene so a
3-point lighting setup and if I go back
through my camera and change my viewport
display shading to render you can see
that the sky color or the world color is
white giving us a nice global
illumination so this is what the scene
basically looks like over here in the
properties window I haven't changed a
whole lot because I kind of want to
emulate what you would get the settings
you would have if you were just using
blender without having changed very many
settings over here the only few things I
have changed are the output resolution
the X&Y the width and height of the
actual number of pixels that you would
render out each frame to of your images
or movie I've set it to 1280 by 720
that's a common resolution 720p on
YouTube and I'll change the number of
samples in this file the render samples
which reduces the graininess in the
scene up to 500 so if I click on render
just a moment you're going to see me
under out this file it will take several
minutes but every time I click on render
I will speed that process up for the
sake of this video in this video I'm
going to actually be rendering out this
scene many many times
time changing just one setting over here
I'll be speeding up the runners we'll
see how each new setting change benefits
our render speed they don't put all
those render setting improvements
together and see just how far we've come
from the default settings in terms of
speed to how fast we can just get this
render speed to get we'll also be
looking at as I said GPU rendering using
an Nvidia CUDA technology but right now
I'm just going to be rendering out using
my computer's processor the CPU speaking
of my computer if you actually want to
compare your render time results to mine
my computer is a windows-based desktop
computer I have a core i7 4790k
processor I have 16 gigabytes of ddr3
memory I'm running my computer off of a
solid-state drive and I have an nvidia
geforce gtx 970 graphics card let's go
ahead now and click on render I have not
changed any of these settings as of the
beginning of this video so let's go
ahead and click on render I'll speed
this photo video up and you'll see how
long it takes up here in this area and
I'll point it out once we finish
rendering
all right through
chica video adding what seemed like just
a few moments there in this video
actually took my computer four minutes
and 14 seconds as runner number one four
minutes and 14 seconds and a little bit
of change extra to render out this
single frame ouch
before we go on to render number two I
want to mention a few things and we'll
change one setting over here the thing I
want to mention is that to speed up your
renders the easiest thing to do is just
choose the right version of blender if
you're in a Windows computer and you're
rendering out using a 32-bit version of
blender when your computer is actually
running a 64-bit version of Windows
you'll be sacrificing quite a lot of
render speed there so if your computer
is a 64-bit Windows computer go ahead
and download the 64-bit version of
Windows you will see a significant
amount of improvement in your under
speeds there several years ago when I
was running out an animation I had a
computer that supported windows 64-bit
but I actually had windows 32-bit
installed on my computer and I had
therefore a 32-bit version of blender
and I got a certain speed of render and
then when I switched over and we're
actually reinstalled when I was on my
computer to the 64-bit version and use
64-bit version of blender my render
speeds improved significantly on the
exact same file the one thing that
changed here now the obvious thing is
the number of render samples I have my
regular samples set up to 500 this is
the setting that actually diminishes the
amount of grayness in your scene it's
set to 500 right now which is good for a
production a production may actually use
anywhere between 200 and 5,000 samples
depending on the actual scene and the
quality that you actually need but what
I'll do here is I have changed my render
output slot from 1 to 2 and that will
leave me a blank canvas to render out to
and I changed my render samples here to
half of the original so down to 250 this
is the only setting I will change now
remember that our original matter time
was over 4 minutes let's go ahead and
click on it now and see how long this
takes to render
all right so we finished wandering out
when they're number two and our time was
only two minutes and six seconds
compared to render ones four minutes and
14 seconds wow what a difference now the
reason I switched over to slot number
two just before I clicked on render was
that we could compare our first result I
go back to slot 1 to our second result
in slot 2 now we can't see very much
difference at all especially if you're
watching this on YouTube but if I go
ahead and zoom into a darker area
typically where you see more noise in a
scene this is the amount of noise that
we can see in our new render with only
250 render samples if I go back to slot
number 1 you're going to see that it has
a significantly less amount of noise now
it really is up to you how much noise
you think is tolerable but really if
you're running out an animation you
might actually save yourself a lot of
hours of rendering especially if you're
running out several minutes worth of
frames at 24 frames per second you might
save yourself several minutes or several
hours of render time depending on your
needs and the number of samples that you
actually need so we improve our render
time by about half just like cutting
down the number of samples but next I'm
going to switch over to slot number 3
for our next render I'm gonna set the
samples back up to 500 because the next
way we could actually make cycles render
a lot faster is by changing the tile
size in our performance section under
the camera tab in the properties window
if we go down this performance section
you're going to see that our render
tiles also that they squares that render
out whenever I'm going out using these
cycles render engine are 64 by 64 on the
x and y axis that means that our squares
are 64 by 64 pixels now what this means
for your computer if you're rendering
out using your CPU is that each one of
the cores or threads of your processor
in this case I'm using a quad-core
processor but the processor actually has
hyper-threading so there are eight
hypothetical threads that's what this
number is here but each of those threads
has to process on its own a 64 pixel by
city 4 pixel square now it turns out
that process
SURS are particularly good at doing
multiple things at once but you don't
want to make them do any one thing for
too long so processors benefit from
having a smaller number here usually a
multiple of two in this case I go down
from 64 for each of these values down to
16 and 16 so that's the only thing they
change here the tile size for my CPU
rendering down to 16 by 16 let's go back
up to render I've changed to slot number
three and I'll click render and I'll
speed this up we'll see how long this
takes
all right so we're number three took
only four minutes and seven seconds
basically four minutes and eight seconds
remember that we're back for our samples
back up to 500 but that's still less
than our first render which is four
minutes and 14 seconds so a little bit
of improvement there you might see more
improvement or less improvement
depending on your specific scene the
next thing we'll change but actually
before I get there I got changed my
tiles back to 64 and 64 the next thing
we're going to change are the light
paths in our scene of course when you
have a scene and you have lights and you
have objects there is bouncing light
around your scene and the light bounces
into your camera we can actually limit
the amount of times that light is
allowed to bounce and that will
significantly reduce our render times as
well so down here in our light path
section again in our properties window
under the camera tab we're going to set
our max number of bounces from 12 which
again is the default down to and you can
choose 5 6 7 8 9 or 10 just a lower
number and by the way yes there are
different types of bouncing lights
you'll see that transmission is set up
to the highest value but if you change
this max value down - in this case I'm
going to use 8 and press Enter it will
limit all these values down to 8 which
will really just turn transmission down
from 12 to 8 but we should see an
improvement there of course I'm going to
change my render slot now to the next
slot just a lot 4 and we get a blank
canvas and now I'll render out again at
500 samples using our original 64 by 64
performance under performance tiles
there so if I click on render it will
see how our result stands for this next
render
all right so read a number for Wow
it just barely beat our original render
which was four minutes and 14 seconds
and this render is in at four minutes
and 13 seconds so just one second better
let's go ahead and compare it to the
original this is run umber four with
fewer light bounces and then if we
switch back to slot number one you can
see really no difference and yes if you
have a dark scene that relies on many
light bounces especially if you have
like a dark room where you only have one
light source and you're relying on like
that light to bounce and fill out and
light up little corners and crevices of
your scene you might see some
differences or if you have glassy
objects that are kind of reflecting onto
other things with caustic lights you
might see some differences there but in
this scene you're not seeing really any
difference from slot 1 or air 1 and
render number 4 but again we only save
just one second let's go ahead and
switch over to slot number 5 and I'm
gonna change those light bounces under
the light path section back up to 12 and
it's at this point that I want to
combine all the improvements that I've
talked about so far in this video into
one render so the first thing I did was
I change my render samples onto the set
blank section from 500 down to 250 we're
going to see here just how fast we can
get the runner to go and using my CPU
before we jump over to using a CUDA
rendering using my graphics card so
we're changing the under samples down to
250 will change our light bounces down
to 8 and under our performance section
down here will change our tile size from
64 to 16 and 16 I think those are the
three things we have changed I've
between a 64-bit version of blender on a
64-bit version of Windows on my computer
let's go ahead and click on it and see
just how fast this render can go
alright so in all other different
setting changes combined we got a render
time of two minutes and three seconds
for render number five that's the best
render speed yet and of course most of
that came just from the changing of
samples what I want to do now is switch
over to talk about CUDA based rendering
now this requires that you have a
probably a Windows PC or a Linux
computer that has an Nvidia based
graphics card I said earlier in this
video in my desktop computer I have a
GeForce GTX 970 graphics card if you're
considering buying a new PC a Windows PC
I would highly suggest if you're
interested in using blender primarily on
this computer that you buy in the base
graphics card for your computer my
computer was built by a computer company
called NCIX I'm not sponsored by them
but they are of an Coover and now a
us-based company that will actually
build you a custom PC using quality
parts at a very very reasonable price
again I'm not sponsored I just really
like my computer
it was very well built and the cable
management was excellent so the way that
you get CUDA rendering to work on your
computer and the settings that you're
going to want to use in fact before I go
any further I'm gonna change all my
settings back so I'll set my samples to
500 under light pass I'll set the max to
12 and under performance all set
actually I'm gonna leave those there
because you'll see why in a moment in
order to use CUDA rendering in order to
use your Nvidia based graphics card to
render you might need to go when you
first get blender into the user
preferences and then under system you
might have to select on the bottom left
your compute device which by default
might be set to none in that case it
just uses your CPU your computer's
processor if you switch over to CUDA and
then you might have to select your
graphics card here I'm using the GeForce
GTX 970 and if you have two graphics
cards or even three I think you can use
all three in blooded that's great if I
click on save user settings now and I
close these references it's all ready to
go except
are here under the camera tab I can
change my device to GPU compute it is
worth noting that I have installed all
the proper drivers on my computer these
are all just the recommended drivers
when you install your graphics card and
you download the latest drivers from an
invidious website at least for Windows
these are just the drivers that you
would normally install just to use your
graphics card as those special cuda
drivers that you need to get it all just
sort of works now if you're like me and
you get a new computer with an Nvidia
based graphics card and you switch the
setting over and you click render before
I do that though I got changed this to
slot number 6 and you click render
Wow Wow will you be disappointed that
render took over 36 minutes several
several times the time that took to
render out using your computer's
processor so what happened well I am
purposely a few moments ago or actually
over 40 minutes ago now and truth be
told it's actually took so long to
render using my graphics card that my
computer actually kind of went to sleep
and locked itself out so I'm not
actually sure how to set an accurate
render time but it's pretty darn close
the reason why it took this long is
because of those tiles and this is the
key to rendering with your GPU your
video based CUDA GPU the tiles down here
in your performance section 16 by 16 is
the worst or pretty much the worst thing
you can use for your graphics card and
that's because graphics cards are not
multi-threaded they cannot do multiple
tasks at the same time but they can do
very well is one big task at a time very
very quickly so if you notice there in
that three seconds and I spent that
video up that 36 or yeah 36 minutes down
to 3 seconds it was only running out one
little square at a time as opposed to
when I was running out with my CPU is
running out eight squares eight threads
eight squares at a time there's a
difference so I'm going to change these
tiles up to either 256 we're using
powers of 2 not multiples of 2 I said
that wrong earlier in the video the
powers of 2 and so 256 here again and so
now let's go ahead without changing
anything else we still have 500 under
samples we haven't changed our light
paths down there still it's at 212 there
let's go ahead now and click on render
I'll change to slot number 7 though so
now we have a blank canvas let's go
ahead and click on render
all right so as you can see just by
changing our tile size up from 16 by 16
to 236 by 256 our render time went down
by leaps and magnitudes down to a minute
and 27 seconds approximately so the tile
size really matters when you're
rendering out with your GPU in fact what
I do here is just one more setting and
adjust my tile size to 512 by 512
sometimes you get better results with
256 versus 512 and one more thing I
change here is the pattern in which it
renders out the tiles if you are
rendering out with your CPU you might
notice that it renders kind of in a
circle outwards and that's called the
hilbert spiral but CPU center rendered
out better when you have a simpler
pattern when it's not having to go and
kind of do math and kind of figure out
what the next coordinate is if you just
go from the top to the bottom or
starting in the center I'm going to use
top to bottom it might be a little bit
faster just to avoid those extra
calculations of what coordinates come
it's going to start out next if you just
go on top the bottom let's go ahead now
and render out to slot number in fact
we'll just use slot number seven again
and compare our results so I'll click on
render
alright so in that case by switching our
tile size up to 512 by 512 we shaved
about one second off a render time down
to one minute and 26 seconds
my last render I'm going to combine all
of the techniques I've talked about in
this video into one render so I'm gonna
switch over to slot number 8 now I'm
gonna leave my device to GPU I'm going
to leave my resolution but I got changed
my samples down to 250 and I'm going to
change my actually going to leave my
tile size at 512 that seemed to work the
best
I have changed my bounces not down to 8
this time but actually down to 6 because
we might actually get faster results and
more of a benefit that way let's go
ahead now and go to the top and this
will be our very last render of this
video let's go ahead and click on render
alright that was the quickest render yet
I remember only took about 43 or 44
seconds that's about five or six times
faster than our original render result
if I compare the two this is in slot
number 8 this is the last one that we
just did compared to the render in slot
number 1 yes we have fewer samples but
really at a glass especially if you're
rendering up many frames in a row you're
going to see a huge huge benefit to
rendering out with a GPU rather than
your CPU and with some modified settings
the last thing I'll say in this video is
that in part 46 of this video series I
made a video on eliminating fireflies or
render noise and in that video you're
going to see some more techniques that
just coincidentally actually happen to
speed up your renders as well these
techniques are to do with bouncing light
in your scene and getting rid of
reflections and caustic lighting that
happens when you actually have a glassy
surface that's bouncing off a light onto
other surfaces so go ahead and check
that video if you want to sweep your
render times even more but that will be
it for this video please don't forget to
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Channel see more videos just like this
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be a before this one thanks bye bye
you