Hello! First couple weeks of this project flew by smoothly, and I am so ready for this next one!
I got some feedback from my professor during our weekly, so I'll be starting with addressing those notes.
Let's get to it!
Fixing the Scene Layout
Now jumping back into Houdini. The first area of feedback I got from my professor was that the floating islands in my scene looked too small and close to the camera. His advice was to place template humans on the islands to get a better sense of scale for them. I realized after doing that that my islands were definitely small, and I had to scale them to almost double their initial size in order to match better.
After that, it was just messing around with their placements once again to get them to fit in the frame.
The massive rock column that shows up at the very end of the shot gave me a bit of trouble, but honestly I think part of it may be due to the shape I made too. Its curvature just wasn't matching up with the reference. When I get to making better islands I'll be sure to adjust both that and then take another look to make sure the scl
Another note on the scene layout, I can't really get a good feel for lighting in my scene until I get higher resolution models in my scene. So that means a finished Samson model and proper islands. Regarding the islands, my professor suggested I try learning to create procedural cliffs, though he also warned that this would increase my (already somewhat large) project scope. I'm not planning to work on this this week, and I plan to talk to my modeling professor on maybe doing the islands in ZBrush (with which I am more familiar, rather than having to learn a new technique in Houdini).
Anyways, now that my general layout has been adjusted, let's get to fx!
Trying the Missile Trail
For the missile trail, my professor suggested volume instancing using copy to points. So, I started by creating a sphere to which I added some noise to the P attribute. I then used VDB from Polygons to get a fog volume that looked like a small smoke puff.
After that, I simply did a copy to points onto the particle trail. This...kind of worked? It looks promising for sure but it's lagging my pc a whole lot which is worrying. I decided to run with it for now though.
After getting the initial trail, I attempted to try and have the puffs decrease in density and increase in pscale according to the particle's age. I used volume VOPs to try and get this effect by multiplying pscale with age (and inverse multiplying with density), however nothing was showing up.
I spend a lot of time fiddling with different methods and settings but unfortunately I wasn't getting anything working. I attempted creating density and pscale attributes on the particles themselves then using a volume rasterize or VDB from particles to create the volumes, but those didn't create the best results.
At this point, I started to get a little frustrated. I must have been doing something wrong and unfortunately it was quite difficult to find anything online about about I was trying to do. I realized too that I was beginning to hyperfixate and that I really needed to move on to other elements before I got stuck on this. So, I'm once again going to put the missile trail on the back burner until I get a better idea on how to go about it.
Here's a flipbook, using the copy to points method:
Adjusting the Initial Smoke and Fire
Ok so, my initial smoke overall I'm quite happy with. The only thing I needed to fix was some stepping near the end of it, from when the Samson increases in speed after being hit with the missile. This was a pretty quick fix, I simply added a trail node at the end of my source to give the volumes more room to work with between frames.
Now, for the fire. The biggest issue here was that my fire wasn't showing up in Solaris. Now, the first thing I discovered was that I hadn't rasterized any density attribute, and apparently Houdini doesn't like that. After doing that, my fire started showing up in Solaris. Woohoo! However, when I went to add materials from the (newly recreated) pyro bake node, something...strange happened. It looked like my fire attribute was coloring my initial smoke instead, which was quite confusing. And when I made the initial smoke invisible, my fire was once again disappearing.
After scratching my head over this for some time, I decided to just recreate my fire simulation from scratch. There may have been some button or setting or something I did that caused the fire to break, and I decided that it'd be best to simply start over rather than just sit there all confused.
I decided to go back to this Rebelway video my professor sent me. In the video, he uses a different technique to create fire than I did, and I decided to try following his method. What I did was use a pyro source node, then added noise to the density, temperature, and burn attributes, before finally using a pyro solver node. Rebelway creates a volume from his source first before importing it into a DOP network. He then plugs the volume source plus a sparse smoke object into a sparse pyro solver, plus various gas noise nodes. For my source, I used a pyro source once again to get my basic attributes set up, plus some attribute noise nodes to, of course, add noise to them. Then, instead of using volume rasterise this time, I used a VDB from particles. I realized my noise didn't transfer and used volume noise nodes instead. Then, I added a trail node to reduce stepping before plugging my source into the DOP network. From there it was just playing with noise like turbulence and shredding until I got a look I liked. Finally, I file cached my simulation and added a pyro bake node.
Here is my setup:
You'll notice that I messed around quite a bit with different ways of creating my simulation source. The nodes on the far right path(s) are the ones I landed on.
Now. Moment of truth. Will it render in Karma?
I think what happened with my previous setup was something to do with my fire density plus the material. Now the answer is...
Yes! My fire is rendering!
I'll probably be messing around with its look more in the future, but for now I'm happy that I have something to present :)
Trying out Explosions
Now, this week has mostly been making adjustments to and building off of elements that I already had in my scene. It's nearing the end of the week now but I wanted to have something new on top of everything else. So, I decided to get started on creating the initial explosion.
I mostly followed Houdini's documentation workflow for creating a pyro burst, though I found this Rebelway video that I plan to go through later in the week.
I started by using a sphere parented to the transforms of the helicopter to find where I wanted the starting point of the explosion. I moved the sphere to roughly around the impact point of the missile, then extracted its centroid to get my starting point. I then added a pyro burst source node. I messed around with values quite a bit to get a shape that somewhat matched the shape in the reference shot. I'll definitely in the future be looking more into how I can get more control over the initial burst shape.
After that, I added a volume rasterize using the pyro burst source quick setup and then plugged in a pyro solver. Finally, I just tweaked the turbulence, disturbance and shredding, as well as increasing the source density and vel multipliers a bit.
I'm getting mushroom clouds I don't like at the ends of the explosion. In the reference, the explosion ends in spikey shapes rather than these mushroom, so in the future I'm going to try and improve the shaping. For now, I'm going to move on to creating the texture in the pyro bake node.
This one was interesting. The fire started out way to bright all around and I had to tweak the intensity and the ramp to bring it down some. The smokey areas where the flame cools I increased the darkness under the "smoke" tab of the node.
Now moving on to Solaris! I imported my explosion SOP and materials and:
My explosion feels way too bright. I pinned the Karma view then went back to my pyro bake node to tweak the intensity once again. In the reference shot, the explosion is extremely bright for a couple frames but then it almost immediately dials down. I had to key the intensity multiplier to achieve a similar effect.
There was one more issue -- all of the smoke was getting colored orange instead of the black that could be seen in the viewport. I think the smoke is missing. Unfortunately, I'm running out of time this week to really mess with it too much so for now, I'm going to leave it where it's at. There's still one more thing I need to do for this week.
Finishing the Samson Proxy
For the end of this week, I'll be finishing off the Samson proxy. Yes I said I'd have it done earlier but I got caught up in Houdini instead. Still, I'm overall roughly on track for the week so it's alright.
There isn't much to say in this section other than that I'm just going to be adding more parts to the proxy just so I can really bulk out all the cpmponents that can be seen on the helicopter. I'm making some adjustments to the shape of the rotors and cockpit too after getting some advice from my modeling professor, Elizabeth Boyd.
I'm just going to skip ahead to the part where the proxy is finished, then. Here it is!
The Final Render
NOTE: My improved proxy has not been imported into Houdini at this point. The rendering process was started before the proxy was completed for the sake of time.
So, when I got to rendering, I ran into two major issues: holdout mattes not working and the missile trail crashing the render.
For the first one, I just went ahead and did a beauty render instead of using render passes. I don't like this, but it's something I'll have to deal with until I figure out what is going on.
The second issue is the missile trail. I wanted to render what I have at least so there was something to show. I have a feeling the issue has to do with the materials again but I'm not entirely sure. Whenever I tried to render with it turned on, I would get a "Fatal Error: Segmentation" before Houdini would shut down. For now, I'll have to do with rendering without it while I troubleshoot.
Here's the render for this week:
I will say, the explosion looks pretty weird right now, especially with the colors and how it interacts with the initial smoke and fire, however I know that in the future that that will be largely covered up by the flames and smoke that come after the explosion. I'll also be working on bettering the pyro explosion itself, as this week was mostly just starting to familiarize myself with the pyro burst tools.
Comments