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>> This is a continuation of our discussion of rendering using indirect illumination
and in this case I want to introduce the concept of HDRI lighting and reflections.
So there's another way to get indirect illumination
on your scene that's not using these flat lights here and so what I'm going
to do is I'm actually going to hide these flat light components temporarily
and so there's no illumination in this scene at all at this point.
There's no lights, there's to flat lights
with that constant shade of indirect illumination.
What I'm going to do is go up to scene environment and I'm going
to go select environment image and there are a number
of these so-called HDR images included with PhotoWorks and what these are,
are high dynamic range images that have wrap around photographs and a number
of different exposures that have a lot of very intense lighting information in them
so they can actually be used to light up your scene, so let me choose the Sky one here.
And actually, I'm going to choose the Daytime one.
It has a more pronounced sun coming
from a certain direction so I'm going to open that up.
Environment Mapping, you can keep spherical because the ones that comes
with SolidWorks are designed for that.
You can imagine your entire scene being enveloped inside
of bubble that's actually infinitely far away from the objects inside the scene,
kind of like the way that ancient people on earth used to think about the sky,
it's just a big shell out there that the stars were painted on and think
about this image as being wrapped on the inside of that sphere,
but the image has a lighting data in it, so the area where the sun is actually going
to be very, very bright and is bright enough to actually illuminate your image.
Now, the strength of that illumination is set by this slider here,
this diffuse material brightness.
I'm just going to keep that at a default for now, and we'll see what happens here.
So again, all I've done is turned on that HDRI environment, and I'm going to go
into the camera here and do a test render.
And this is what I get with my test render.
So a few things to notice, first obviously the image is very blown
out because the HDRI is way too bright.
We can turn that down though, that's easy.
Also, there is some directionality here.
You remember in that HDRI image there was a sun, and it's pretty clear that the sun is
up here somewhere casting a shadow this way.
You also see that there's a blue color cast to this shadow because the sky is blue
in the HDR image and it's actually that that blue is carrying into the illumination,
so let's go and back to our scene dialogue and turn
down how much light we are getting from the HDRI.
I'm going to turn it about to half and we'll see what's happening here.
And that's looking a little better, at least in terms of the contrast.
We basically turned down the strength of the sun and the sky there, and, you know,
we've got a much clearer blue cast to the whole thing,
but we can at least see our object.
Now, HDRI lighting can be very nice.
You'll getting some nice diffuse lighting here, and if I was compositing this
into an outside scene, you know, this might be good, but you do get a few things
like this color cast if it's not a completely neutral HDRI and what's worse is
that you can't control the direction that,
you can't control the directionality of the HDRI image.
There's no control for doing that in SolidWorks right now.
What I'd actually have to do is rotate everything in my assembly relative
to the origin if I wanted to change the direction that the sun appears
to be hitting the object at, which is not a very elegant way to do things.
However, there's also another use for HDRI imaging, which is in the reflections.
Let me actually change the, I'm going to change the material of our vessel here
to just the regular polished aluminum, and I think by default it will be polished aluminum
so I can just delete that so that we get some reflections here.
And I'm also going to go in and change our HDRI image to, let's use the Kitchen image,
which I think is often the default.
Notice I also have a slider here foreign environment reflections and one other thing
that HDR lighting gives us is nice reflections of that photograph off objects
that we have in our rendering so I'll leave it at here for now and we'll see what we get.
Okay, this came out kind of dark because that kitchen lighting wasn't nearly as intense is
that sunlight HDR so I can probably turn it up,
but you can see that we're got some nice environmental reflections
on our shiny object now and if you look closely it actually looks
like the object is inside a kitchen.
So that can be a very nice effect for trying to render something in context.
To kind of take advantage of the best of both worlds,
what I will often do is I will use the HDR only
for reflections and not to light the scene.
So I'll turn the diffuse material brightness all the way down.
I'll just leave the reflections there for now
and then I'll bring my plane lights back to do the lighting.
So if we do this rendering you know now I've got the lighting
in a much more controlled way because I'm using my plane lights,
but I also get the benefit of these reflections from the environment.
Now, obviously, one problem here that that we can see the plane lights reflected
in the object here, and so you may have to be kind of creative as to how you place those
so that you, it doesn't take away too much from it.
Other renders have the ability for those plane lights to be invisible
to the camera or invisible to reflections.
To my knowledge, PhotoWorks does not provide us that ability,
so if the object can see plane lights, they're going to be reflected in it by that.
But so you kind of just have to balance your needs in terms of having more precise control
over the lighting versus what kind of reflections you need, but it's good to know
that you have both of these options in terms of indirect illumination of your object
in terms of either using these plane lights and/or getting illumination
from an HDRI image wrapped around a sphere that the whole rendering set is inside.