The Mill Collaboration - Week 2 - Update 2

Early Test of the Fracture

New file with improved Uv's

New file with improved Uv's

I now have a working Houdini file that writes out all the faces within the fracture and maintains decent UV's. UV's and Textures are an area I'm working to improve and Houdini has a different approach to the process. As I mentioned in the previous post I experienced serious issues with grouping and Uv's. I learned the hardway the importance of pipeline integration and have gotten a taste of how it works. Unfortunately it was through mistakes and problems that I created. Sometimes you need to make mistakes to truly understand and grow from the experience. Houdini and VFX in general are very finicky and unique in terms of integration. It's one thing to work in Houdini when you are using Mantra alone, when it comes to teamwork you need to be open and flexible to all sorts of integration procedures and be very aware of your team's needs. Learning to build within Houdini logically to best support any artists in the future is crucial. Below is a sequence of exploded views that should allow texture artists to easily understand the layers of the fracture and also paint and texture the effect.

The new Houdini file takes into account UV space and incorporates two separate fractures based on the points of two spheres in order to create the inside and outside geometry. Sine the object is a cannon ball, and the Sand Solver was beyond my capabilities, I wanted to create smaller chunks of "congealed, hardened" gunpowder that could be shaded.

New Node Tree

The following images show the bullet solver and dopnet including the bullet settings. The rolling ball still has issues. It no longer floats like it did originally due to to much force and not enough friction. Now the problem is ballencing the angular velocity with the other parameters and the uniform force node I am using to add more impulse. 

The Python node is the key to separating out and controlling the geometry. A friend helped me work out the script and showed me the value of Python within Houdini. It was crucial to help offset the inside and outside pieces of geometry within the cannon ball.  Until now my only Python experience was inside Maya with Mel from the Intro to Programming for Visual Effects. I'm looking forward to next quarter and advanced scripting to dive deeper into Python. The next photo includes the uniform force.

Another issue that I need to address are the glue constraints. I have not been able to get them to cooperate so for now I am releasing the glue based on frame count. This week I hope to solve that problem and idealy add some dust or debris to really sell the shot. 

Top View of the New Fracture.

Week 2 Update 1 The Mill Collaboration

Week two has brought us progress and problems. The majority of my time is spent troubleshooting the fractures and trying to wrap my head around the bullet solver and how it communicates and interacts with the rest of the solver and nodes. The second version of the file shown below could only write out to types of Alembic files. The way I built it made it difficult to assign groups and I couldnt find a workaround.The UV's where spaghetti, so I tried to use an Attribute Transfer of the UV Projection past the fractures, in an attempt to  clean things up. After working so hard on trying to create primary and secondary fractures, it never occurred to me what the outcome of UVs would be with so many broken parts. 

Another difficulty that I encountered was the concept of pipeline for VFX from Houdini into Maya. Until this point all of my Houdini work had been done inside of Mantra so working out the details and building with the idea of passing on the project did not go well. One of the reasons I'm rebuilding the file is because I found that I had painted myself into a corner in terms of exporting the file to the required format and making sure the UVs would not cause problems for my teammate. I was so proud of what I had accomplished due to the steep learning curve, it was an abrupt wake up call when I passed off the Alembic file and watched first hand how messed up it truly was for future texturing and look development. I was also completly unaware that the force I used to project the ball forward wasent allowing it to spin. It looked to me in HOudini like everything was fine, but once a texture was placed on it it was clear there was a major issue with the animation. 

Making a Mess of Topology, Learning the hard way

Making a mess of geometry. Next we used the Decimation Master lugin to remesh the model into a manageable poly count allowing us to move the model into Topogun. This is where I learned all about the importance of edge flow. I made a lot of mistakes as I found out later when trying to UV the model. This is a classic case where you need make mistakes in order to learn from them. The next topology work I do will have more thought out lines. After unwrapping my first attempt at UVing the character looked more like a spaghetti monster.  

Next was to play with some topology software called Wrap 3 by R3DS. They have a 15 day trial so I gave it a shot. It seems to work best with hi-resolution scans but I was able to get some decent topology after a while very quickly. The more I played with it the faster the wraps took.