Haeckels Microscopic World

[fortysix]

Hey guys, 

I'm trying to model a microscopic world by ernst haeckel, and I want to start with the Legion Nassellaria, as you can see attached there are 3 intersecting spheres with either holes and spikes. Now this is the tricky part for me. How can I scatter points and divide them into two groups by region? I have always messed it up. The thing is that it needs to be quite regularely. Any hints?

And one general question, when do you use VDBs, and when Polygons? I'm quite new to Houdini and I'm still figuring out where the strengths of each ones are. 

[konstantin magnus]

Welcome Paul,

here are some notes on polygons vs VDB in regards to modeling (btw: odforce has a section for modeling questions ; ):

polygons advantage: good topology, look good when subdivided, dont need that much memory, dont freeze you viewport.

polygons disadvantage: takes lots of planning to develop procedural modeling workflows. boolean operations will likely harm your topology.

volumes advantage: you can just melt any kind of geometry together. it allows models you could hardly model by hand (caves and the likes).

volumes disadvantage: take loads of cpu power, results in really high resolution meshes if you want to keep the details. proper UVing can be tough.

 

I attached two examples, one purely in polygons, the other one mixed:

spikey_holey_sphere.hipnc

uv_squab.hipnc

VDB modeling is definitely something that should be explored more!

Edited October 10, 2016 by konstantin magnus

[fortysix]

Hey Konstantin,

thank you! You helped me a lot with these two files! I was exactly looking for something like you did within the point wrangle node. Pretty clever to group the points by neighbouring pointcount. I'd never guessed that. 

I will try around today and let you know. 

[fortysix]

Well, I just can't figure it out. How do groups work? How can I invert a selection of your group "spikes" and select all the other polygons instead. I wanted to extrude the Pollen and Peak it afterwards, but somehow the selection got messed up. 

spikey_holey_sphere_02.hipnc

[konstantin magnus]

there is a "not equal" sign in the combine-tab of the group sop that can be used to invert groups. just put the same group name in both fields.

group1 ≠ group1

[fortysix]

well. I did a more complicated way around. But I'm getting closer

 

 

spikey_holey_sphere_03.hipnc

[konstantin magnus]

good progress!

[fortysix]

There's another question I've got regarding Particles. The thing is that I want to simulate flying pollen. They should be carried away with the wind but then stick on a surface, where they slowly fall down along the surface. 

I have merged together a wind force and a file where particles fall down along a surface. But the thing is that the wind force still applies to these particles. 

Where can I remove the force from these particles and apply another one afterwards? With 2 POP Networks?

 

pollenflight.hipnc

[Atom]

One way might be to leverage the Group inside the PopWind. Have it only affect those particles not in the surface group. Inversely add an extra Gravity force that only affects those on the surface.

 

[fortysix]

Hey Atom,

thanks for your help. I have to admit that I still haven't figured it out yet. I will try in the next couple of days. I'm currently trying to get something else to work. 

Is there a way to animate the local control within the Polyextrude SOP in that way, that every item will be animated differently?

I all I could tweak was a different Distance Scale. 

I would like to generate multiple funghi, which should react like this one: https://vk.com/doc175465340_437706639?hash=bdeeea02809a44203b&dl=e98f795521525eeabc

 

my hip file so far:

 

RandIndividual.hipnc

Edited November 10, 2016 by fortysix
image

[konstantin magnus]

If you want the arms to move individually I would create them based on curves. Animate the curves e.g. with VOPs, CHOPs or a wire solver and sweep or polywire them afterwards.

Here is a rough attempt.

tentakel.hipnc