A frustrating journey towards the completion of a fairly easy scene worth 4 seconds of footage.

... on which I am still stuck on :D

Since I am intending to add some hair to my main character, but got no idea as of how to do that yet, I will leave these scenes for later and complete all the others that are easier, then, depending on time budget, I will decide if I go on with the hair thing or not. Because of that, and and also because I improved the original model a little bit, fixing some geometry errors that came with zBrush reimporting, and this was enough for Advanced Skeleton to go nuts and completely screw my already created walking cycle. 

Kill me now

I tried to readjust weights unsuccessfully for a couple of hours, and I am still unsure as of what will be faster: fixing or doing it again from scratch, so meanwhile I figure out I jumped to the next "easy" scene. Oh, my naiveity...

This scene is not complicated: we have the robot walking and the kitten following through. We only see the robot feet so I decided to redo the walking cycle just for the legs. 

Using the side view for keying the main controller of the rig, 

so every step stays where it should be instead of reverse-positive

 moonwalking. I set each step every 22 frames, since that´s the 

song beat tempo on that specific part and I want for the

 movement to match it. 

 During the process, I spotted some minimal, yet noticeable mistakes, like corrupted mesh...

Fixable by readjusting manually the vertex.

... and badly adjusted texture...

This one is corrected by moving the vertexes in the UV map.

To be able to place the model in the right angle, I had to go back and think on how the scene is composed. Basically I will have three pieces of footage: the green screen cat, the background, and the rendered 3D model, taken in that specific order. First, I went to Nuke and composited the cat over the background to make sure they match in angle:

This is not properly edited yet, just matched to check the perspective is ok.

Once I have my video, I create a new camera and place it as an image plane, so I can move the model in a way it matches perspective and the proportion with the cat. Once done, I proceed to create the reflection for the glass by creating a simple box and adding a mia_material_x_passes with full reflection.

We can notice how screwed is our rig from the eyeballs 

and eyebrows floating in the middle of nowhere, 

but doesn't matter since we are only rendering the feet... for now. 

We will have to fight our fears soon enough :c

Now, is time to think about the shadows. The HDRI used for Image Base Lighting is giving us a nice soft shadow here, however, doesn't exactly matches the one of the cat.

So what I do is to create a spotlight, and keep playing with the preferences until I achieve the result I want. 

Too sharp & dark and still not the right angle. 

Shape looks weird.

  

I moved the spotlight so it casts a larger shadow.

Right angle, still too sharp... but there is a catch:

we can see the hand, which means I'd have to also 

animate the arms.

Keep trying to get rid of the hand to see 

if I can save myself some animation.

There we go... still too sharp, though.

I tried a different approach, choosing  Depth Map shadows 

over Raytrace. Quite noisy...

Keep playing with parameters. Too subtle.

Bingo!

 Then we got a problem. Render passes do not work. Shadow pass comes as your regular Beauty, same for Diffuse-without-Shadows. Ambient Occlusion looks like an alpha map:

I kept on googling the issue but found nothing that solved it, so I just wrote Lee with some cries for help. (EDIT: Ambient Occlussion pass works just fine now. Happens I didn't checked the "Ambient Occlussion" box in the menu. Doh!  Other passes are still a problem, though. ) Meanwhile he gets back to me, I gave it a go to render the reflection. 

Nice reflection, but  massive flare. Try to get rid of it. 

Trying by selecting the object and set the "receive shadows" box 

unchecked. Gets rid of some black spots, but flare still there. 

Since I assume the flare comes from the spotlight I created

to cast the shadow explained before, I exchanged  bright values 

between the spotlight and the Final Gather, lowering the brightness

of the first while increasing the second. Still not there. 

There! Was all to do with the material. 

Decreased the glossiness and the refraction.

Cool, time for some testing:

Dang! 

Two problems arise here: first, dancing shadows. Second, there is no alpha. Also, movement feels off, as if she was a... ahem... robot. I am still figuring out whether I like this or not, maybe doesn't matter since we will have her legs passingby in front and we won't notice, let's see.

The alpha thing, after spending hours of checking and unchecking parameters here and there - render stats, Image based Light sphere, Camera settings, render passes options... - happened to be the image plane. I moved it using the offset option so it doesn't show in the camera anymore and that fixed the problem. 

Now, time to figure out what's wrong with the dancing shadows.

To be continued...

::: UPDATE :::

While I bumped into a couple of methods as of how to get rid of the flickering shadows, they seemed too complicated and time is running out, so I will go back to learn that later and render with just the HDRI lighting for now (this one, says the internet, doesn't cause these sort of artifacts... and is actually right since I just did the render and looks pretty smooth).