Page 1 of 2

Tutorial: Adding a Fire VDB to a scene.

PostPosted: Mon Oct 10, 2016 9:52 pm
by Sighman
I would like to start by saying that the OctaneRender for Carrara plugin does NOT support the native Carrara fire primitive. The built in fire primitive is not a true volumetric and it does not expose any volumetric information that the plugin can use to render it in Octane. Instead, you can load an externally generated OpenVDB file into Octane using the Carrara fire primitive as a proxy. You can then assign a volumetric medium to that primitive to produce a fire like effect. This tutorial will be a step by step guide on how to add and configure an OpenVDB file to a Carrara scene.

First you need to obtain an OpenVDB file that you want to add to the scene. OpenVDB files can be created in some 3D modelling tools including Blender, Houdini, and Realflow. You can also download OpenVDB files from some websites including http://www.openvdb.org/download/. The file I will be working with is fire.vdb that I obtained from here: http://www.openvdb.org/download/models/fire.vdb.zip.

1) Open Carrara and load the smileyjump scene located in the Browser under Scenes->Animations->Smiley Jumps.
2) Add a fire primitive to the scene. Place it to the left of Smiley (your right) and scale it up to a nice size.
3) With the fire primitive selected go to the effects tab. (Remember, there is nothing you can configure on the General tab that will effect the result rendered in Octane.)
4) Under Octane Volume (OpenVDB) set the Enabled flag and click on the [File] button.
5) Locate and open the Fire.VDB file you downloaded from http://www.openvdb.org.
6) Click on Import Settings.
7) You should see Absorption Grid and Scattering Grid set to density and Emission Grid set to temperature. There is nothing else to set here so close the window.
8) Switch to the Shading tab (NOT the texture room). Click on the little drop down button and select New Master Shader. Then click Edit.
9) Change the Top Shader to Octane Medium and then change the Medium channel to Volume.
10) Select a dark grey for Absorption and Scattering.
11) In the Emission channel select Texture.
12) Set Power to .02 and set Texture to a RGB Color: Orange

Switch back to the assembly room and then open the Octane Viewport (Edit->Octane Commands->Open Octane Render Window).

Scale Mode
A new scale mode was added to the Octane Volume (OpenVDB) Effect.
Fit to Proxy - This mode fits the loaded VDB file into the area reserved by the proxy. Note that this mode will distort the scale of the original VDB object and may not work well with animations.
Fixed Scale - This mode preserves the original scale of the VDB file. The proxy still provides position, rotation, and scale but it does not force the volume to be rendered within the borders of the proxy. A slider and two edit boxes on the new Scale Settings dialog allow you to scale the VDB volume to fit within your scene. Since each VDB file can provide its own initial size, a loaded VDB volume can appear way too large or too small for immediate use. The min-scale/max-scale edit boxes allow you to provide a 'reasonable' range for the Scale slider. Once a min and max scale has been entered, the scale slider can be used to pick a value between the min and max values. This should allow you to more easily tweak the size of the volume to better fit your scene.

Here is my scene. NOTE it does not include the required .vdb file.
smileyjump_fire.zip
Fire Scene
(108.24 KiB) Downloaded 809 times

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Tue Oct 11, 2016 6:17 am
by EddyMI3D
Thank you a lot!
This is very helpful!

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Wed Oct 12, 2016 2:44 pm
by protovu
Thanks, Simon.
Looking forward to experimenting with this!

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Sat Oct 15, 2016 6:57 pm
by tschwenke
Thanks alot :)

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Thu Jan 12, 2017 12:17 am
by protovu
Hi Simon,
Finally got to looking at this, and your tutorial works very nicely. Thank you.


I did a smoke sim in Blender and was able to export .vdb files, which seem to be importing nicely into the file list.
Wondering now about fluid sim with .vdb?

Best regards,
Rick

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Fri Jan 13, 2017 12:57 am
by protovu
Hi Simon,
Here is a little smoke sim, via blender .vdb export that I managed to import into Carrara thanks to your help. It is a little mysterious working in Carrara with this.
As you noted, we can only see activity in the Octane render window.

Still very nice to have this capability.
Now........all I need to do is figure out how to work it into a project....ha.

Thanks for your work,
Rick

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Sun Jan 15, 2017 9:39 pm
by tschwenke
Looks cool :)

When I import VDBs into Carrara, I have to turn them by 180 degrees and activate "Fixed scale." That's all.

VDB and fluids would be great :)

Best wishes,
Thomas

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Mon Jan 16, 2017 4:08 pm
by protovu
Hi Thomas,
I came across a video below which shows an interesting way to get particles into a .dae file, which I assume could be imported into Carrara. Unfortunately, the video runs so quickly that I am having trouble doing some of the steps. If you have Blender, perhaps you might take a look? The link to the script is below the video (show more). If I can figure this out myself, I will let you know and post results.
Granted, this example does not show fluid, but it seems interesting, and potentially useful in the future.

https://www.youtube.com/watch?v=JvQxiuchiDQ

Best regards,
Rick

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Mon Jan 16, 2017 9:31 pm
by tschwenke
Hi,

This guy converts particles to meshes and exports them to DAE. I have no idea why this guy is doing it and what it's for, but it seems to be a bad idea :cry:

It will take hours to load 1000 particle meshes into Carrara :o

You should use a Python script to create the CSV particle files. It works really good that way. If you don't have a script, I can look into it. I usually use Houdini, as it's faster and has more features than Blender, so I'd have to convert the script a bit, so that it works with Blender.

Or you can ask Simon to implement ABC files with Carrara. ABC files can store particle data :)

Best wishes,
Thomas

Re: Tutorial: Adding a Fire VDB to a scene.

PostPosted: Mon Jan 16, 2017 10:08 pm
by protovu
Thank you, Thomas.
We are getting into an area which is very new to me....scripts.
So, I hesitate to ask Simon to do something on a subject I understand so poorly. And, I would not want to bother you with this either, but thank you.

I will try to read up on the ideas that you are suggesting.

Once I have a script, I need to figure out how to use it. It looks like there is a python panel, or text panel in Blender. I guess if I could just plug in some text to achieve something,
this could be possible......even for me.

For my part, I am extremely impressed with Blender particles. If Houdini is better.......wow. I will investigate. Blender sure has a nice price, though. And given that my investigations
are just for curiosity , the price is helpful.

Best,
Rick