In the previous episode we began to age our camera by adding some details to the Lubitel sticker and the lens metal using layer masks, projection painting, and manual painting.
In this episode we're going to age it further by throwing some dust onto our camera it's going to sit in all the crevices of the camera.
It will look like it's been sat on a shelf for some time and hasn't had a proper clean in a while.
We're actually going to let the power of Ambient Occlusion do most of the work for us here.
Ambient Occlusion is a method of mimicking soft shadows produced by natural ambient light.
But it can also be used to isolate crevices within our object, which can then be used to simulate the dust that often settles in those crevices.
This is not only going to add some age to our object but also adds colour variation to our object that makes it more realistic looking.
Ambient Occlusion first needs to be generated for our object in the "Object" menu or in the "Objects" palette.
Click the "Ambient Occlusion" option to start the generation.
This might take a few minutes depending on your computer hardware, so pause the video and take a break.
You can monitor the progress of your Ambient Occlusion calculation in the bottom right of the UI.
There is a limitation with the way we've generated our ambient occlusion.
It's calculated based on how many vertices our model has.
if you have a model with a high number of vertices, the Ambient Occlusion will look smoother.
There is another method you can use to bake ambient occlusion in Mari, which doesn't have the same limitation and that's inside the "Modo Render" palette.
Inside the "Bake" tab you can select "AO" and produce a bake that you can store to a Geo-Channel.
We aren't using Geo-Channels in this series, but you can check out the documentation regarding that if you're interested.
Be aware that baking Ambient Occlusion with the "Modo Render" palette may result in a longer render time.
We need our Ambient Occlusion to be stored to a layer so we can use it to create a dust mask.
We can actually use an "Ambient Occlusion" procedural layer to achieve this.
It takes the Ambient Occlusion we just generated and stores it to a layer.
We're actually going to produce our dust mask in a single layer and introduce the concept of mask stacks to you.
Using a single layer that contains multiple adjustments in its own mask stack is going to allow us to have a single mask layer that's non-destructive to create a black and white mask that will show and hide dust in the areas we need.
Without any other layers selected in the "Layers" palette, create a new "Color" procedural layer which needs to have the colour of our dust.
Again, we're just approximating the colour here.
This is likely going to be adjusted later.
Name that layer "Dust Mask" and then select it and click the "Add Mask Stack" button.
Adding a mask stack means instead of applying a single paintable mask to our layer, like we did with the scratches on the metal parts, we can actually assign a whole new layer stack to a specific layer's mask.
Let's take one of the masks we painted in episode 5 as an example.
If i click the mask in the "Layers" palette and activate the "Current Paint Target" with the I key in the viewport we can see the mask we painted.
If i want to add any type of adjustment or even procedural to the specific mask I can't because it's only a single mask applied to a layer.
However i can convert the single mask to a mask stack using the "Add Mask Stack" button.
Then it will let me add further adjustments to this specific mask.
This is really useful because it gives you a whole new dimension of freedom with painting your masks as it lets you add stack adjustments such as Contrast, Inverts, or Levels that will be applied to only your mask and not the layer as a whole.
So once we've added our mask stack it's going to be added to our layer with an icon that looks like this.
Click the icon to enter the stack.
The first thing we need to add to this stack is the Ambient Occlusion we just generated.
Click "Add Procedural Layer" > "Geometry" > "Ambient Occlusion".
Once added, while holding the I key over the viewport, if i select "Current Paint Target" while the "Ambient Occlusion" layer is selected you can see what this ambient occlusion map looks like.
As you can see it uses darker colour information to simulate soft shadows in the crevices of the object and lighter colour information to simulate smooth flat surfaces.
So we need to invert this Ambient Occlusion map because we only want our dust mask layer to appear in the white areas.
White in the mask retains the current layer and black reveals the layer underneath.
So we need all the white areas of our Ambient Occlusion to actually be black and all the black areas to be white as we only want the dust to appear in the crevices.
So in our mask stack click "Add Adjustment Layer" > "Invert".
Then we can add a "Levels" layer to tighten the levels between the white and black color information so we can really focus our dust into the crevices of the camera.
With these "Levels" adjustment sliders, what i'm going to do is make it so the white areas are tighter in the crevices by reducing the "Mid" "Output", and raising the "Black" "Output" slightly.
I'm adjusting each slider ever so slightly while checking the viewport to make sure i'm getting the result I want.
Then using the I key in the viewport to select the "Principled BRDF" shader.
I can check how the dust is looking while still adjusting the sliders to make sure the levels changes i'm making are producing the dusty look we're after.
Once we're happy with that we should think about adding some breakup to this mask to make the dust appear more organic since dust never settles in perfectly smooth ways like this.
You can achieve this using procedural layers and layer blends.
In our mask stack click "Add Procedural Layer" > "Procedural" > "Noise" > "Cellular".
i've chosen this particular noise procedural because i found it to work the best while experimenting with this previously.
However you've got a whole range of procedurals you could try out here to see if you can achieve anything better.
Since our layer stacks are non-destructive you have the freedom to try out as many things as you like.
With this "Cellular" layer we need to set the layer blend to "Overlay" so the cellular noise only appears over the lighter areas of our Ambient Occlusion.
You can then adjust the opacity of this layer using the opacity slider so it's not as intense.
Reduce the "Size" of the cellular generation to around 0.03 so it looks like tiny specks of dust.
The "Type" allows us to determine how the distance between each cell is calculated by Mari to render the cell noise.
You can really see how this affects the cells when the "Size" is set to something much larger than our dust.
Changing the "Type" to "F2 - F1" seems to produce a more accurate dust result as the edges of this procedural generation seem to feather out nicer than the other types when the cells are small enough.
If you want to add dust into other areas on the camera, for example i'd like to add a little more to the top of this LOMO logo then create a new layer and put it underneath the "Cellular" procedural layer.
We need to put it under the "Cellular" layer because the cellular layer needs to overlay the rest of our mask in order to achieve this dusty effect we have going on.
If i was to put the layer on top of the "Cellular" layer it would paint without the dust particles present.
Overlays always need to be on top of the paint you want it to affect.
Take the "Super Soft" brush from the "Shelf" under the "Basic Brushes".
You also need a white colour and then start to paint where you would like to add more dust.
And now we have a dust mask that quite nicely simulates dust on our object.
Feel free to adjust the dust color using the "Dust Mask" layer.
You can also adjust the opacity of the dust mask using this slider depending on how intense you want the dust to appear.
In the next episode we'll start to venture out of the "Base Colour" channel and into a new channel: the "Bump" channel, where we're going to look at creating the bump effects on our camera.
See you there!