Category Archives: 3D CGⅡ

CryptA01-3D Compositing Procedure(Maya+Nuke)

23rd March 20213D CGⅡ, NUKEⅡXuran Ni

I tracked the plate in two parts before but I realize that I only need one camera, in this case I re-track the plate with suitable lens undistortion and other given parameters, and it works very well, better than before.

3D Tracking

I write out the camera and some planes as reference and import them in maya. I also improt the undistorted plate image sequence as background, as well as HDRI.

We do not use HDRI to cast shadows because it will cause shadows on undesirable places. I just choose to use area lights to mimic the effect.

camera sample should be larger than 3 if using casting shadows.

More info: https://docs.arnoldrenderer.com/display/A5AFMUG/Shadow+Matte

Multipass rendering

Mid-drag the assets in suitable collections under the layers that we created, we can create Override to exclude the unwanted assets in the scene. In this case, we just separate shadow and no shadow scenes.

To save time, I choose to render different layers separately, as GPU rendering does not support shadow matte alpha channel, I deicide to render geo_no_shadow layer by GPU and shadows layer by CPU.

Because I forgot to render with ID pass, so I have to roto the part that I want to correct separately and merge them afterwards. It is important to care about the alpha channel in each node, and I just turn the alpha into black colour in roto node. And we need to grade with alpha mask, or premult in advance, otherwise it may affect the original plate.

Final Compositing

Import camera for CG compositing

10th March 20213D CGⅡXuran Ni

First we need to import image sequence, we need to make sure the image sequence name is ended with number, avoid A01_0001.tiff this type of file name, otherwise maya cannot import image sequence automatically.

I just import the camera created from nuke and view from the imported camera. I made a sphere and put it on the position of the axis that I created in nuke.

The image sequences can be hidden:

Import the correct HDRI in Alnold SkydomeLight, set the camera visibility to zero, the environment effect will be kept but HDRI will be removed.

Gear animation and Clock design

22nd February 20213D CGⅡXuran Ni

We can use expression editor (under windows>animation editors) or node editor to make linked animation between gears. And we need to freeze transformation of the mesh before we create the expression.

Also, in order to make sure different sizes of gears match with each other, we need to make sure the ratio of the number of gear teeth to the radius of the gear is equivalent.

Therefore, I tried to design and make an animated steampunk style gear clock, I found some online pictures as inspiration.

In this case, I just combine diffrent types of gears together, and made a antique style pendulum and clock face. I also linked four gears with the same modulus to do the rotation.

Clock design

Hierarchy and Solar System

15th February 20213D CGⅡXuran Ni

This time we learnt hierarchy rules and then made a simple solar system. In order to make individual movement on different spheres, I set the pivot to the centre of the object itself to do rotation, and set it parent to the locater in the center to do the revolution.