- [Instructor] The next level up in environment light
is a Panorama of a High Dynamic Range Image or HDRI.
This is also known as Image Based Lighting or IBL,
we can apply an image to our environment,
and that will provide a background
and also illuminate the scene,
but it does need to be a high dynamic range image
to work well.
That means that the pixel values
represent physical intensities of light,
if you just drop an ordinary image
into the environment slot,
you're not going to get good results,
it needs to be a special HDR image
in order to properly illuminate the scene.
Let's add one in the rendering menu,
choose environment in the common parameters roll out,
we'll see a slot for environment map,
click the big button labeled none,
and we get the material map browser,
we want to navigate to maps, OSL environment,
and choose HDRI environment,
and that's a special map type,
it has color correction controls
for high dynamic range images.
With that selected click okay,
we get another dialogue
in which we need to browse for a file,
and unfortunately,
we're actually taken to the 3D max program file directory,
and we absolutely do not want to link to a file
that's not inside our current project.
I've got a file prepared, it's in my project,
and that's on my desktop,
so click on desktop,
and navigate to exercise files,
scene assets,
images,
scroll down a little bit,
we've got one here labeled quarry 028K.HDR,
and that's an image from the website hdrihaven.com,
it's got a whole bunch of free images available,
with that file selected click the open button,
and it may take a moment to load in the scene,
because that's a fairly heavy image file
it was almost 100 megabytes in size,
and you may need to click or navigate in the view ports
to force them to refresh.
Once the image loads,
we can see the background and the perspective
and the physical camera views,
because I've chosen the environment
as the view port background in the views menu,
view port background, I've chosen environment background,
and we can orbit around,
take a look in this perspective view,
orbit with Alt and middle mouse,
and look around we've got a full 360 degree environment,
and that includes an actual sun,
which is at the correct physical intensity
to illuminate our scene.
All right, very cool,
let's see what this looks like in a production rendering,
I'll click on the active shade button on the main toolbar,
to initiate Arnold,
and again, that may take a moment to load
because that's a pretty heavy image file,
once it does we can see that it's pretty dark,
I expected it to look very bright, like a sunny day,
like I see in my view port.
Well, this is happening because of the default settings
of the HDRI environment map,
let's make some changes to this
to bring it into the proper brightness range.
To adjust the parameters of this map,
we'll need to open up the material editor
and launch the material editor
from its button on the main toolbar,
and then drag the environment map into the center panel
of the material editor,
when I release the mouse, I get a popup dialogue,
do I want to instance or copy?
I want choose instance,
so I'm actually working on the map
that's in the environment slot not a copy.
So choose instance and click okay,
and that map note is already selected,
and we can change its name up here in the parameters,
we'll call it ENV map and press enter,
the reason that we're getting such a dim result
in our active shade rendering,
is because of a feature called clamp,
we'll see it down here in OSL map parameters.
In the appearance section, there's a checkbox labeled clamp,
and that's limiting the amount of brightness
that can come out of this map,
turn that off, turn clamp off,
and immediately in our active shade,
it looks much brighter.
We can easily adjust the brightness of that map,
by adjusting the exposure value here,
and just like in the exposure control window,
this works in exposure values,
similar to F stops on a camera,
if we increase the exposure value by one,
we'll double the amount of light,
and now we can see that's overexposed.
Now we could bring the exposure value here up or down,
in order to get a result that looks good
to us in the rendering,
but I would like to take a more scientific approach,
I want to set this map's brightness
to a more or less physically accurate value,
and to do that,
we'll need to enable exposure control,
I'll set this appearance exposure back down to zero,
and let's go into the exposure control window once again,
so in environment and effects
we have exposure control and it's currently disabled,
so let's enable it,
we'll choose physical camera exposure control,
we'll want to disable
use physical camera controls if available,
so that the global exposure value
will affect all cameras in view ports.
Turn off use physical camera controls if available,
and we see it's overexposed in our active shade,
if this were a physically accurate light source
for a bright sunny day,
the global exposure value should be something
in the range of 13 to 15.
Let's try an exposure value of 14,
and it looks very dim in our active shade,
that in turn tells me
that I need to increase the brightness of that map,
so back in those OSL map parameters,
let's try increasing the exposure,
value of one, not bright enough,
two, still not,
three,
four,
the value of four was probably in the range,
let's try a value of five,
and that's actually just a little bit over exposed,
we can see that here on the ground
there are some areas that are a little bit hotter
than they could be,
so I'll bring my exposure back down to a value of four.
Now, if we look in the view ports,
we'll see that they're extremely blasted out,
and we can compensate for that,
using this appearance view port parameter,
I can bring that down to a value of 0.1,
and now we see in our view ports
we've got the correct brightness for that map.
Okay, so now I know that I have
the more or less correct brightness for the map itself,
I can close the material editor
and make some final fine tune adjustments
to the camera exposure,
it's a little bit on the dark side here in our rendering,
so let's brighten it up just a bit,
we'll do a split exposure here,
we'll set the exposure value to 13.5,
that'll brighten it up by half a stop.
We want to make sure, once again,
that our image control settings are neutral,
we want to set our highlights to the value of one,
and shadows to a value of zero,
so we're getting a perfectly linear response
to the image control,
and we're not actually changing the contrast.
And finally, we can get a more pleasing result
if we use the daylight standard setting
of 5,500 degrees Kelvin
for our white balance color temperature,
so we'll set our white balance to a manual temperature
of 5,500 degrees to correspond to the daylight setting
on a real camera.
All right, so that looks pretty good I think,
we've applied a high dynamic range image
and brought the image intensity
and the exposure control into the correct ranges,
the background behind the building,
the sky does look a little bit dim to me,
but we can adjust that separately,
we'll take a look at that in the following movie.
And that's how to apply a high dynamic range image
to the environment to illuminate a scene
and provide a background.