Animaton input

Hello again...
So here we are... Back... Again...

Down to business, input connection on animation nodes...
Sounds kinda interesting right? (nope probably not).. Basically not to long ago i had to time remap a series of shots and i couldnt alter the original animation, i needed a method of re-timing mutilple shots at different rates... With a bit of reading around i discovered the input attribute within animation curves, this is pretty easy to manipulate.  I just used a locator with a custom attrbute called "Time" that i could animate each shot... this was then connected into the input connection of each object (this was easier to do with a little piece of script).

Ok so thats pretty interesting right... No youre right... still boring
Next step

I was next looking into some shellac type material attributes for vray, this material needs a similar fall off to the facing ratio and ramp trick but with an exponential curve as opposed to linear. I tried a few different methods with adding curves with multiple points but the result wasnt as smooth as id like. So i started by keying the reflectivity of my shader i then opened the graph edtor and changed my curve to be 0 at frame 0 and 1 at frame 1 (this can be highed but because im in vray, 1 is fine). i then made my curve to be exponential...

This really isnt enough and probably makes no sense ("Why would i want to animate this specular"). What we need next is a samplerinfo node with will read out information about the surface of an object, so the attribute we need is the facing ratio.
Facing Ratio:
The facing ratio will sample each face of an object and return a value based on its angle to the camera. The value is between 0 and 1 this is why our keys were between 0 and 1.

So we connect the facing ratio to the input attribute of the animation curve. Escentially the value is remapping the value of the facing ratio from linar to exponential, and connecting it to the reflection.

So that pretty much covers it. Off the top of my head i cant think of any other amazing uses for these methods yet but if anything comes to me ill be sure to post it.

Displaced

Well, im back.... again (yeah..again...)
So im trying to keep this as up to date as possible, i dont have heaps of time.. but ill try...
With work this past year ive had to learn a lot of vray for maya...
Im gonna start kinda documenting what i discover...should be "fun"...

This last week or so ive been batteling the displacement demon... and i tell you something.... its a trickybitch sometimes... not so much the standard displacement... But vector displacement. With Maya 2012, standrd mentalray shaders have a vector displacement input... but for me that wasnt going to work (damn you vray). Then again, vray 2.0 has the advantage of 2 vector displacement modes.  Absolute and Relative, this is handy because Mudbox can export to Absoulte that can be converted within maya to relative. Normally it wouldnt make much sense seing as both work equally well, but its handy to understand the difference between the two because then you can always revert them either way or convert displacments you are supplied

Heres how its done in the Maya Hypershade:
Connect your Absolute image into a Multiply node with the following connections.
R to Input 1
B to Input 2
G to Input 3
Then youll need to multiple the following Values
Input 1 x 0.5
Input 2 x 0.5
Input 3 x 1

Following this step will use a Average +/- node, Connect that to the  3D [0] connection, then from within the atribute editor you can add the following values.

Input 1 + 0.5
Input 2 + 0.5
Input 3 + 0

Lastly everywhere where i read explained to connect it through a blender node (conneting it to color 1 and setting the blend value to 1) the only reason i could think this was for was so the XYZ values were convered to RGB (this wouldnt normlly matter but at a guess i susspect because of the vray vector displacement it naturally looks for a RGB value)

The next step isnt tricky but easy to miss. You need to drag your original image into the displacement slot of your shader, this will auto create a displacement node for you (sue me im lazy), you then need to set a manual connection from the R value of the Blend node to the Displacement value of the Displacement node (Do not worry about the vector displacement attribute thats for mentalray)

Within the geo you'll need to create a displacement attribute and set it to Vector (with the steps ive just run through it will not work with "vector absolute")

Note:
From what i could tell the vray process, detects there is a displacement and then uses the attributes from the displacement attribute overide to select the R+G+B Channells as required an displace the mesh.

Over its a trick process and there is a bunch of advanced parts that will help your displacments along but for the time being this will begin to help yu understand the basics.

As per usual i apologise for any confusing Grammer + Spelling

~Macky

CA Process

In my last post i explained Chromatic Abberation. Well i did have enough time to go through how to actually do it.

Adding Chromatic Abberation:

2D Addition

I've made a rough composit of a CA process on a still, mind you this process is more manual than i usually use, also i base it more of a shot by shot basis. I have a Gizmo i use in nuke that saves me a large amount of time.


The reformat simply changes the format so ignore that. Basically each shuffle node pulls out the seperate rgb channells. Then the red and blue channells have a god ray applied scale, after this ive merged the channells, so first red and blue then merge the red/blue to green.

The result is very slight, but it helps add to the subtle edges to the image.



3D Addittion

Now this is slightly more tricky. So start by setting up 3 different renderlayers RED/GREEN/BLUE. Render your image with its intended Refractions, this is now your green channell. Now, increase the IOR (Just remember to note down your IOR) of your reflections (a small amount is all that is needed, but you'll need to play with your settings yourself) this will be your red channel. Lastly reduce your IOR from the FIRST IOR, this last channell is your blue.

Your results should looking something like this.



Now to display how to easily merge the 3 channells. Ive decieded to add all the channells to black, but this can be done easier (this uses more nodes than it needs).


The shuffle pulls the r,g,b channels out of each of the images. and then they are merged over black.


This merge method is a little bit lighter on the nodes but also simpler. The first merge adds blue too green, then the second merge adds red to blue/green. Overall the result is the same.


Left: Chromatic Abberation Refraction - Right: Standard Refraction


Once again the result is quiet small but the overall effect helps tp sell the shot. These effects can be replicated in AE and any other compositing software. Hopefully this answeres any questions....

Aberration Chromatica

When it comes to compositing its important to remember everything or near enough to everyhting.

Chromatic Abberation (CA) is one of those everythings...

What is Chromatic Abberation:
Basically CA is colour of light waves being refracted different. You are probably not aware but light is treated differntly when it passes through objects but is does, you just need to look at a diamond or glass prism.

Notice in the diamond how faces are refracting different colours, while the glass prisms caustics reflect from red through to blue.

Youre probably thinking where this comes into compositing, this effect doesnt just affect 3D glass refractions. The lens itself is also refractive (go figure....) and the lower quality the lens the more CA is caused (this is why CA is more common in camcorder lenses than in DSLR's). When the light is focused through the lens and the colours refracts to a different area on the CCD. CA is also most noticable when there is contrast between light and dark, similar to light wrap. Light wrap and CA are a great combo.


This diagram kind of explains the effect of CA

How do i replicate it?
There are a few plug-ins and scripts out there, but like with most effects you dont always have access to them and you are kind of left short.

When doing this type of effect you simply need seperate the channels out then radial/direction blur the blue and red channels, and lastly re merge the channels... Quiet a really easy process.

What about 3D?

Yeah what about 3D!
Now with some renderers you can have the option to choose dispersion with refractions. This will slightly alter the IOR of the indavidual channells. If your renderer doesnt have dispersion option you'll have to go old school on it. You render your reflections with slightly different IOR's then in post merge the different rendering into the red/blue channels (also bluring my be needed to help blend).


Conclusion
Chromatic Abberration is by far the best way to add that little extra something to your renders/composits, But you need to use it lightly.

Do not pass GO. Do not collect $200...

Well Ive started over...
The renewal for my website as come and gone and i decieded not to. I think i can use a blog easier, this will help with the updating... Between Blogger, Flickr and Vimeo i should be able to update everything.
Ive got a few projects im playing with, and we are working on a few things at work also.
But ill try and keep the updating going.
~Macky