Vine Gen #2

March 4, 2019 Bradley Sakaguchi

there are three groups any point can fall under root, node, and stem. root points will search for node points around it to grow. The root point will then be “killed” (taken out of node and root group) and be transferred into the stem group which are the points that will be skinned.

all points are initialized with a direction attribute and they will attempt to grow in this direction the best they can. the root points grow by looking for the points nearest to them and drawing vectors between itself and all the points. The point will then grow to the vector that is most similar to its direction attribute. Those vectors override the initialized direction attribute of the near points for the next iteration.

Vine Gen #1

February 28, 2019 Bradley Sakaguchi

I will be making a vine generator solver for Houdini that grows vines on any mesh the user inputs.

The solver works on this basic Vex. This is basicly saying, every frame, if there are any points in the root group find points in the “node“ group and place them in the “root“ group. This create a loop that expands the root group.

Fantasy Plant #3

January 29, 2019 Bradley Sakaguchi

This week I worked primarily on creating the simulation for the seed pod. I used a combination of Pyro and Vellum soft bodies to create the effect. This simulation shows all the functionality of the set up and some tweaks.

I imported an alembic from maya and separated the mesh into its individual components. I then made two types of vellum soft body objects, strut softbodies (green box) that were applied to the petals, and much firmer Tetrahedral softbodies (black box) for the stem, center, and seeds. The pink box is the glue constraints that connect all the individual elements and the decides how firmly they are connected. The final constraint node is a pin node that is applied to stem. This pins the points on the stem in place until enough force is applied to it to break. The strength of the breaking threshold is determined by the sort and point wrangle nodes, which apply an attribute to the points on the mesh. This attribute is determined by the proximity to the end of the stem that is connected to the pod. The connecting point breaks at force of 0 and the other end breaks at point .002. I used a field force that is referencing the velocity field generated from the pyro sim in order to have the vellum interact with the pyro.

I also rendered the pod shader on a ball to see how it held up in a different situation. I think it did a good job besides the SSS radius which needs to be changed based on the scale, but that was expected.

Fantasy Plant #2

January 19, 2019 Bradley Sakaguchi

Since last Post I’ve done quite a bit of work. I completely redid my pod Material and added a stem. These are going to be my two main pieces So I thought it best to sink a lot of time into them.

The changes that have been made to the pod are, getting the noise pattern to be the correct size and shape on the pod, using ss radius for the coloring instead of ss color, and using coat as the primary specular and using the normal specular pass to only set the anisotropy for the refractions.

The other thing that I was working on is Arnold AOV’s. They are a very powerful tool that allows for massive changes in post such as relighting. You are able to assign different shaders to different AOV’s such as AO and ShadowMatte. Using LPE (light path expressions) you are able to split up each individual channel to each individual light. Light path expressions look something like this, C<TD><L.'hdri'>.* this specific expression is to specify the sss for the specifically the HDRI light group. All the expression are on: https://docs.arnoldrenderer.com/display/A5ARP/Light+Path+Expression+AOVs. This is great for de-noising, shader tweaks, and relighting.

This is the same render but edited in nuke to have less diffuse contribution in the stem, more specular contrast, and less key light contribution.

comparison

Fantasy Plant #1

January 15, 2019 Bradley Sakaguchi

While researching plants I thought of a plant I used to play with as a kid while at school. I did some research and found it was called a jewel weed. I played with them because sometimes when you touch them they explode. I thought it would be fun to have this really explode with a pyro sim, that coupled with the seed pods interesting material, I thought this would be a very interesting project.

The First thing I went about doing was a test of pyro, to make sure I could make it collide with objects. The Pyro sim was very simple just a pyro explosion and a static solver interacting with it via a merge. I then exported it as VDB sequence with a density and heat field. I use an arnold volume and volume shader to teak the look of the sim.

I then went about modelling the seed pod. I kept it low poly and made sure to take into account at render time smoothing and subdividing. I then started on the shader and found that a combination of refraction and subsurface was what was working best, i’m still in the process of refining this but the material attributes are in the images below. The displacement is driven by 2 simplex noises, one fractal for general roughness, and one rigid for distinct wrinkles. Both noises were stretched around the model and with some remaping and clamping I found some very good results.

Although I think the biggest breakthrough was using the randomwalk attribute in the subsurface scattering. I think that is what really made it feel like the light was penetrating thought it. The issue is that this can increase render time and with such a complex scene optimizing renders will be a constant battle.