A quick breakdown of what we have done for this week is that we reshoot the footage for the first shot because of the camera motion. I am also focusing on learning pyro and particle effects in Houdini for the portal effect.
Here is the progress video of this week:
Here is my WIP render of the portal effect. (Emission was not working in this render.)
I was not familiar with the pyro and particles in Houdini, and I wasn't sure where to start. However, one of the mentors from the Mill sent out a YouTube tutorial on making a magical portal during the last progress meeting. Therefore, I followed the tutorial to understand the workflow, and then tweak everything afterward.
Here is the link to the portal tutorial:
The portal was made with a few steps. The first step is creating the create smoke with pyro as advection for the particle effects. To do this, I used a tube to get the outward normal, and then transfer the normal attribute as velocity onto the object that I want to use as the source of the smoke.
The second step is to get the smoke with the pyro solver. After the smoke is working, I can just plug it into the popnet as the advection source. I created four different versions of the particles by changing turbulent noise in the PointVOP so that I will have different looks that I can layer on top of each one. After I am happy with the particles, I cached out the simulations so I don't need to simulate again and again.
The third step is to move the points of the simulation to the frame of the portal with the attribute transfer node, so it looks like a portal. I can add a transfer to rotate and scale the cached simulation before and after the attribute transfer to change the look of the simulation without redoing the simulation.
The last step is to add color. It was done with a color node and attribute wrangle. I used @age as the attribute of the color ramp. For the point wrangle, I adjusted the emission intensity of the principle shader with @emitint = abs((@age/@life) - 1). Therefore, the particles will darken as it ages.
One of the issues I had is the rectangle shape is not working well with the attribute transfer because one side is longer than the other and the edge is pointy. The blend radius on the attribute transfer is calculated in a circular shape. Therefore, the shorter side will always be squeezed more toward the inside. I had to play with the dimension of the smoke and particle object to make the left and right sides wider, so they look better after the attribute transform. Additionally, I also had to make the four points of the portal rounder to have more points for the particles to move to. Otherwise, all the points at the corners will be squeezed into one point at the corner.
Here are one of the passes of the simulation:
I create the portal opening and closing motion by scaling the frame of the portal that particles are copying to, and also the scale of the cached simulation.
Overall, the portal still needs a lot of detail changes, and here are the list of goals that I hope I will be able to accomplish next one or two weeks.
Adjust the emission intensity and color of the particles.
Make the simulation move faster.
Adjust the opening and closing animation.
Add ground plane as collision, so the portal will interact with the ground when it is placed at correct hight since it should be just above the ground a little bit.
Add the part that is inside of the portal.
Add interaction with the motorcycle going through the portal.
Create the light streak effects.
Test out bringing the portal from Houdini to Maya with Alembic and Bifrost. (Alternative solution: copy sphere onto points, but will create larger file size)
Special thanks to my teammate Nathan, Sanat from team Specter, Mitch from team Splash and professor Fowler's help.
Here are some more references:
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