Houdini caching large OBJ geo files

[charliejh]

Hi,

Im working with a pretty complex OBJ file which I'm going to be running some dust and smoke effect over. (theres rocks and signs etc).

However the file is really slowing down the sim and its impossible to work with.

I've read that you can change 'File Mode' to Automatic and it will cache the geometry permanently to disc, but it will not let me change it as it is greyed out.

What is the best way to use my geometry but not let it slow down my dust sim after changing it to a static object.

New_desert_geo_edited_v002.obj

[Atom]

One thing you can do immediately is stop using the OBJ format. Create a new GEO object, in the File node browse to the OBJ you have. Then drop down a ROP Output Driver and save the OBJ file in the .bgeo.sc file format. This is a binary version of the Houdini's geometry format along with a compression algorithm.  Replace any references to the former .OBJ with the new .bgeo.sc file. It should be smaller on the disk and will load a lot faster. This might help your sim run a little better.

 

[charliejh]

Thanks Atom,

Helped me out earlier in the year and you've done it again. I'll give this a crack and get back here if there's still problems. Cheers

[charliejh]

On 9/26/2016 at 1:35 PM, Atom said:

One thing you can do immediately is stop using the OBJ format. Create a new GEO object, in the File node browse to the OBJ you have. Then drop down a ROP Output Driver and save the OBJ file in the .bgeo.sc file format. This is a binary version of the Houdini's geometry format along with a compression algorithm.  Replace any references to the former .OBJ with the new .bgeo.sc file. It should be smaller on the disk and will load a lot faster. This might help your sim run a little better.

 

 

Hi Atom, 

The bgeo.sc file seems to be working fine, however I cant seem to get it to work with particles/pyro. Usually I would select the geo, then click 'Static Object', then in AutoDop, select the geo then tick 'Use Deforming Geometry'. This does not seem to effect the geo.

How would I go about setting this geo up so particles can collide with it?

Thanks,

 

Charlie

[Atom]

Stand alone particles should work inside a bgeo.sc, but Pyro needs to be written out as VDB and you need to convert it explictly to VDB using a ConvertVDB node before you write them out as .vdb files.

Check out this link for an image of the VDB output setup.

[charliejh]

 

I might be doing something wrong with the ROP Output Driver.

So I made a geo node, and inside I set the geometry file in the file node to my OBJ geo.

I then made an ROP Output Driver, linked it to the File node, and then hit 'Save to Disk'. Houdini then saves each frame, but how do I go about actually using this?

Do I select the Geo node on object level then hit Static Object then go from there?

[Atom]

Just return back to the File node and browse to the newly generated .bgeo.sc file. You no longer need it to reference the .OBJ anymore. You are loading a different File.

[charliejh]

Okay understood.

I still can't get the geo to work with particles or pyro, they continue to pass straight through.

I'll attach the geo as an OBJ. Would you be able to have a look and see if it works for you?

Thanks for all the help.

Charlie

New_Desert_Geo.obj

[Atom]

 

There are a couple of problems with that OBJ file. For one it is the wrong scale. Also there is duplicate geometry inside it which may cause render problems. What I often do is just drop down the Simple Male or Female character and check the size of my imported geometry. In this case the entire object needs to be scaled by 0.01. Then I'll break apart the input geometry into groups so I can isolate them for use. In this case I isolated one road sign and set it on fire.

In this case if you create a particle system with the tool shelf then create a pyro on top, the particles will fall through the ground. What you can do is just drop down a new blank DOP Network. Before you click that tool shelf button to create the pyro click the drop down near the Brain Icon in the bottom right and switch it to the newly created DOP Network. This is how the shelf tools know what AutoDopNetwork they are targeting. So you would end up with two simulation networks in this case.

ap_work_with_desert_road.hiplc

Edited October 5, 2016 by Atom

[charliejh]

Thanks Atom,

I've been using a Null done to scale it by 0.01 . Is using a transform node better?

Is the duplicate geometry able to be deleted within Houdini or do I go back across to the original Maya file and remove it there?

I'll be working on this, this time tomorrow so I'll let you know if I come across any more issues. 

Thankyou!

 

Charlie

[charliejh]

Okay so correct me if I'm wrong.

You've created that 'Geo_Collision_floor' node, which has merged the ground and the road geo together, and thats what you have made a static object with in the DopNetwork.

Im unsure how those delete nodes work. How are you selecting individual parts of the geometry and applying them to each delete node?

 

 

[Atom]

If you middle click on the File node you'll see there are 277 groups. Each one of those groups could have it's own material applied to it. Each group can be selected by it's name, like Rock17. But you can also select all groups named like Rock by adding the * wild card character. So Rock* will put all rocks into a new group. Follow that up with a Delete Non-Selected and you have isolated all the rocks, etc...

That is just my way of dealing with 277 groups. In the prepare node I have narrowed it down to five major object groups.

I merged the ground and the road just so I could present a single object for collision. You could separate them out into two unique collision objects if you wanted them to each have separate physical bounce properties.

Edited October 10, 2016 by Atom

[charliejh]

Okay understood

In your example earlier, the particles are only reacting with the groundplane you have created, not with the geometry.

The particles need to be blown across the geometry above the dunes either side of the road. Unless I am missing something this does not solve the problem of the particles clipping through the geometry. Sorry I must be missing something

[Atom]

The particles are just residing in their own AutoDOPNetwork. There is no reason you could not add as many obstacle geometries as you like to that network. The ground plane was just a convenient way to create a new AutoDOPNetwork.

[charliejh]

Thanks Atom, I realized I had to change the collision to surface, not volume, which solved most of my problems haha. Thanks for all the tips!