Welcome to lowering your cycles a render time.
So looking at the cycles wonder engine we're going to have cycles cpq vs. g.p.
It's important that you go through this process now so that you know which one is quicker and B how
to set it up for your particular computer.
So we're going to go through how to change your render settings.
You will have to run multiple tests as we go through and different scenes will have different characteristics
depending on their complexity.
But in general all that will follow a similar pattern.
So let's hop back on over into blender.
So once you've saved your user preferences we can close down the user preferences window.
And I'm going to expand these windows on the left hand side.
Now the render tab is this one on the camera on the left on the properties panel.
So once we've clicked that we have a series of options.
And as we scroll down we can see there are lots of them to go through.
And we're only going to go through the very basic ones at this point in time.
First of all are we in cycles.
No we're not.
So let's change it.
Because when you're using blender render the only thing you can use is you'll see you.
It does not use the GP at all.
So we switch that from Blender end to cycles render.
We get a few other options.
First of all device cpq or g.p you compute depending on which one you select will change which component
blender uses to perform the rendering.
So let's change that now to GP you compute.
Now the two of the things we're going to pay attention to at this point in time is the dimensions of
the render.
Now this point we're only focussed on the resolution and by default it's set to 10 ATP or high def.
Now we notice there's a slide underneath that says 50 percent so actually this is going to render 50
percent of 10 ATP.
So you can adjust that to get a good feel of rended times.
If we rack up fall from 50 percent to 100 percent I think it's going to take about four times longer
to do the render than if it's at 50 percent and it it'll be four times quicker if we knock that down
to 25 percent.
So let's scroll right down.
There's one of the option that's very important that's under performance.
If we open that up and scrolled down we have tiles.
Now this is very important and will vary from card to card graphics card to graphics card or processor
to processor.
So x and y settings play about those and we'll find that some things take longer than others.
So let's leave it at 64 64 and render up this cube here.
So let's go to render and render image.
And there we go.
It's rendered it out and we can see the time at the top here is just over one second.
Now this cube is rather basic So we cant really do any testing with it because the render times are
just going to be around one second whatever we pick.
So what I'd like you to do is go to the section assets and open up the BMW files.
So let's go and open up our section assets now.
So here we go.
BMW twenty seven blend.
If you open that up you should end up with something like this on your screen and it's got a convenient
notepad remember to save the file as you go.
Now the person that set the scene up we can see that they used an Intel seven three point eight gigahertz.
That's They've got a g force GTA 770 and they've noted the times beneath using the GP you and s.p. you
now feel free to explore around our scene.
We can see how it's constructed and we'll be doing a similar thing later on in fact we zoom out.
We can see that this is all these two cars are in a bowl of sorts and there's a couple of cameras all
set up when you go to render your image up the top here with render render image of it.
F 12 or indeed there's a button under render on the properties here.
When you hit render you can see it starts building our scene.
First of all because it's much more in depth and then it starts rendering.
Now we're on g.p you computer.
And if we scroll down the dimensions are set to 50 percent of 10 ATP which is fine you want to leave
it at that for these tests on performance.
We can see that the tiles size is currently set to 128 by 128.
Now I'm not going to sit here and wait for the whole thing to render out as we can see on the top here
it's predicting about 12 minutes in total.
However if we change vs here the x and y you see that what the impact of that is so this tile size refers
to how many pixels by how many pixels were actually rendering at.
So if I cancel the Render with this little cross on the info head up.
And change this to 12 by 5 12.
You see that it renders a much larger area at once so it needs to build the scene first and do some
calculations.
Oh we can see it's building up this large area here and it's doing that all at once.
Now depending on the settings your graphics card all s.p. you will render at different times.
In general these numbers are larger with graphics cards and smaller with s.p. Use If I go up to our
asses GP you compute and switch that to see you stop the current render.
And then scroll back down and perhaps put this at 64 by 64 so slightly smaller than it was before and
hit the render key F 12.
You'll notice that I have after it's built one two three four five six seven eight squares.
So it's doing 8 renders out once whereas the GP does one at once.
So here that is because I have a four core processor that's got hyper threading So it acts as if it's
got eight cause us able to do eight things at once.
In general the faster cpq renders other ones that can utilize the whole of the processor.
For the longest time.
So if we set this whole scene up at 12 by five 12 for instance or even bigger than that.
If we set it up to a thousand.
Well let's do the Fall Reds.
I've got those the wrong way round.
I do apologize but I want half of those.
So 540 and 9 6.
The I think of my maths is right.
So that'll render the whole scene at once.
But instead of using all eight cores Let's stop the render instead of using all eight.
Cause if I go and render this image it will just literally use one core.
We got the orange borders of there and it will be rendering it only using one call which is not very
efficient.
OK it's Challenge time.
I'd like you to get to your best render time if you haven't done already.
Please open up the BMW 27 dot blend file from the outset pack and I'd like you to perform multiple renderings
with the GP you and see you leave the render at 10 ATP at 50 percent and only adjust the tyre or size
to see the effect on render times.
So you have to get a pen and paper or a spreadsheet out and record the times or indeed a good record
in the little notepad that's conveniently placed in the lower right hand side of this blender file.
Now do that several times and post your best render time s.p. you or GP and the tiles size in the discussions.
Just a word to the wise before you go off and do that if at any point you think that the time is going
to be astronomically high and then I would recommend stopping the render and changing the tile size.
In general the GP use will do better with larger tiles sizes and CPS will do better with smaller but
that will vary depending on your particular hardware.
So Paul as a video now and give that a go.
Welcome back.
Let's hop over into blender.
So we left our scene like this.
Now I'm not going to bore you all with the rendering times at the moment.
I've already gone off and done that whole so I'm going to open one of the files I've been working on
which is the BMW 27 render times.
So how did I fare on my computer.
So I'm just going to pull this out completely as you can see I've done lots and lots of tests on my
computer.
Now I've gone all the way from 16 by 16 all the way up to 512 by five tough.
You don't have to have these particular numbers by the way they don't have the match as you can see
reds matched underneath.
These are direct divisions of the resolution that were rendering to.
So here we have 16 by 16 you can see it takes up to 52 minutes.
I actually did not wait for that one to render 32 by 32 it gets down to 30 minutes 8 minutes 7 minutes
7 minutes 23 7 a half 723 So that looks like that one.
There was the fastest that the GP was going to render.
Now we can see that I got is even lower.
When we had a rest matches just because this happens to be closer to the ideal value for both my graphics
card and this particular scene I've made a couple more notes here.
When it comes to the CPM skill to pull that out so we can read my drivel.
Let's just.
Pull that down so you guys can read what it says as well.
Okay so s.p. you time it looks like as you can see here five high 12 for cause we utilize briefly and
then a rapid drop down to two cause.
So my max utilization on the Mac is eight hundred percent.
That's for cause with four hyper threading units running at once.
So 100 percent would be one core and eight would be the eight cores in total.
So the longer the whole process can be utilized the faster the render.
So here we have eight by eight done in four minutes and 10 seconds so the first thing to note here is
that my See you on this particular scene is significantly faster than the GP you so I will probably
have cycles using the s.p. all the time.
Now if you imagine if this was one so one frame that you were rendering of a let's say 24 frames per
second and it was just a 10 second clip or what does that work out to be.
I can spell calculator.
There we go.
So let's just call it four and a half minutes because it will differ.
It may get more complex or more simple as it goes.
But four and a half minutes would be a good one times 24 so that's how many minutes it's going to take
to do one second.
A hundred and eight minutes to do one second of video of animation.
This particular resolution.
And that's not even 10 gtp Wow.
That's a lot.
So let's have a look at the Reds match.
And as you can see there's no real benefits from going this high.
So in this case the eight by eight s.p. tiles on the s.p. was the well known 16 by 16 was the fastest.
Now these three here are actually all within the margin of error even 64 by 64 I'd say.
If you run these tests again and again you'll probably find that these three are pretty much the same
across the board.
So eight by eight to six to 32 by 32 It seems to be the ideal position for this.
Now on the blender website if I can just take you to the blender website here.
Blender dot org.
Leave the page there.
Okay.
When we go to the downloads area there is a series of demo files and that's where we've got the BMW
benchmark file from.
And I've opened up fishy cat as well and run it on that and the class from the class class room is incredibly
intensive.
So when we recommend using that one is just a quick render test.
Now a fishy cat itself.
I've done that one as well.
And he was the little mascot of the last version two point seventy four.
So if we go back into blender and I open up my fishy cat render.
We can see that a similar thing happens.
Let's just pull this open here.
I haven't done all of these but as you can see on the GP you it runs the best time there is here in
the same place it was last time I believe.
And we can see that this lot here all within the margin of error.
Any way it could quite as easily flicked between the two.
Maybe not this one here.
Not quite sure but see you times we can see that in this case 32 by 32 happens to be the best.
So again these are all pretty much within margin of error eight by eight in this case was outside of
that but these three here 16 by 16 to 64 by 64 my s.p. You were the fastest.
Now you may not think oh well that's a few seconds difference.
But again if you're doing an animation where you've got 25 renders per second I mean that's really the
minimum you'll be working too.
If you wanted 60 frames per session it's going to be a very long wait.
Those few seconds add up to huge magnitude.
So after that you've done this what I would like you to do of course if you haven't done already is
post your best friend time to the discussions I really want to see what type of hardware you've got
whether you've used your GP or see you the tile size you've used and how quickly you managed to render
out that BMW would be great to see the differences in the technology.
Now it's also very important this point again to highlight the render time.
As you can see six minutes is quite a long time to wait for something to come out.
However if we go back to the BMW we were working on you'll notice as you start rendering the image and
was going to switch just to see you.
And we know from my tests that actually around 16 by 16 is going to produce the best results.
If I now go and render this whole buzz away in the background.
But you can see that you can get a relatively good idea of how it's going to be rendered by just zooming
in.
And if that wasn't good enough that's the final thing there.
Well it's not actually the final if you follow it through right to the end.
You will spot there was a bit of compositing where a light appears as well on us seen but there we go.
You should now be able to set up a blender to render cycles as quickly as it can on your particular
computer.
And I will see you in the next lecture.