Author Topic: VDB workflow testing  (Read 3408 times)

Offline paq

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Re: VDB workflow testing
« Reply #15 on: June 18, 2018, 03:49:54 AM »
Hi Matt,

I'm really thrilled by this .vdb export feature !
I'm mainly use Clarisse, and as you can see (attach), there are not lots of options inside the vdb attributes and the volume shader, (and I have never used multi-res .vdb).
Anyway I'll love to give an hand with my limited technical knowledge on the subject. I usually use Terragen to render skies, and use some nasty alpha tricks to modulate Clarisse atmosphere.

I had tried once to build a complete skies from different .vdb clouds, and it wasn't that great ( https://www.behance.net/gallery/53179645/Monolyth ).
That said, the cool think with Clarisse, there is no problem to deal with multiple Gig's of data ... but generating huge data is maybe not the goal for the moment.

You might maybe be in touch with Greg Barta (aka Xilofoton). He seems very focused on atmosphere / cloud rendering with "traditionnal" package (Houdini / Mantra / Redshift and Clarisse). Here's is his blog : https://scivfx.wordpress.com/tutorials/  ... maybe you guys are talking the same language ;)

(let me know if you want his mail address)
« Last Edit: June 18, 2018, 03:54:43 AM by paq »
Gameloft

Offline Matt

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Re: VDB workflow testing
« Reply #16 on: June 20, 2018, 01:50:39 AM »
Let's post test renders in this thread.

Testing Round 1

https://tinyurl.com/ycbscxxk

In this package you'll find:

  • 1 VDB file that was exported from Terragen (vdb_calib_01_export_v001.vdb)
    VDB files that were exported from Terragen (vdb_calib_01_export_v001.vdb and vdb_calib_01_export_v003.vdb)
  • 1 OBJ file of a square plane, 10 km by 10 km (10km_calib_chart_v002.obj)
  • 1 MTL file for the OBJ (10km_calib_chart_v002.mtl)
  • 1 texture map for the square plane (10km_calib_chart_v002.png)
  • 1 FBX camera that was exported from the Terragen test scene (vdb_calib_01_camera_v001.fbx)
  • TGD scene files for Terragen renders of the original cloud layer (not the VDB) hovering over the calibration chart
  • Renders done in Terragen of the original cloud layer (not the VDB) hovering over the calibration chart, from which the VDB was exported
  • Screenshots of settings for the camera and sunlight used in the Terragen renders

The square calibration chart should be a Lambert diffuse surface. It has four quadrants that should have albedos of 4.5%, 18%, 36% and 72%. The texture map is intended to contain these values if read into a renderer with gamma 2.2, but sRGB colour space should be close enough.

The 3:2 image aspect ratio may seem an unusual choice, but I did this because it matches the default aperture/film back on the camera, and I thought this might reduce the chance of the FOV being different when you enter the 50mm focal length or import the FBX file.

Our first goal should be to render something in various 3D packages that closely resembles vdb_calib_01_shadow_of_black_cloud_v001.tif (or .exr)

Matt
« Last Edit: June 21, 2018, 05:15:55 AM by Matt »
Just because milk is white doesn't mean that clouds are made of milk.

Offline Matt

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Re: VDB workflow testing
« Reply #17 on: June 20, 2018, 01:57:36 AM »
vdb_calib_01 renders from Terragen:
Just because milk is white doesn't mean that clouds are made of milk.

Offline Matt

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Re: VDB workflow testing
« Reply #18 on: June 20, 2018, 02:17:22 AM »
Ideally the VDB will load into your scene and appear approximately in the right place above the calibration chart. It won't match exactly because the VDB export doesn't account for the curvature of the planet, but the difference in position should be no more than a few pixels in the render. I will fix this in one of the next rounds.

If you have to make any scale changes or position changes to get something close to my renders, please let me know.
Just because milk is white doesn't mean that clouds are made of milk.

Offline ajcgi

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Re: VDB workflow testing
« Reply #19 on: June 20, 2018, 10:20:02 AM »
Hi Matt! This is exciting! I am gonna slowly bring stuff in to Houdini today around the actual work I'm meant to do here. ;)
First issue for me is that there's a scale difference between the grid and the camera of 1000, taking one unit in Houdini to be one metre.
Screengrabs attached. Cloud comes in at the same scale as the grid and sits in place. ;)

82823-0

Offline pokoy

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Re: VDB workflow testing
« Reply #20 on: June 20, 2018, 12:46:47 PM »
Downloaded, all FBX files worked fine, camera is positioned correctly for me in 3ds max. However, I don't get anything from the VDB, it's completely invisible, even increasing density to high values doesn't make it show up. When testing some example vdb file it worked, yours won't display anything.

I am not sure if it's user error on my side so let's wait until someone else comments here, maybe it's just me. Will give it another test tomorrow and see if I missed something.

Offline paq

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Re: VDB workflow testing
« Reply #21 on: June 20, 2018, 01:32:05 PM »
Hi pokoy,

The .vdb loads fine in Clarisse, however the density attribute (or property), usually called 'density' is named 'Easy cloud 01'. There is probably a way to remap the data in 3dsmax.

So I have a first setup in place, done by hand has Clarisse don't load .FBX.
Scaling is right (it's a 10Km large scene).

Direct light exposure is set on 1.5, and I have an env.light on -3 (???)

With the a default volume shader settings, and the overall density reduce to 50%, it looks more like smoke than cloud. I'll post the scene on Isotropix web site (may I Matt ?), because I'm really curious what kind of trick we could use to get a proper cloud look  8)

Cheers.
Gameloft

Offline ajcgi

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Re: VDB workflow testing
« Reply #22 on: June 20, 2018, 01:36:40 PM »
To begin with I also got nothing. It took 3 of us here to figure it out at lunch. Ultimately, the density attribute in the vdb is still named 'Easy cloud 01' and not 'density' which Houdini is expecting.

I've now got the scene up to the point where the shadow works! The density on the pyro shader had to be reduced to 0.2 and then it was all go. More images attached. There's a slight offset in shadow position.

Offline pokoy

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Re: VDB workflow testing
« Reply #23 on: June 20, 2018, 01:38:13 PM »
Ok, good to know it works. I've tried Arnold today, will repeat with Corona tomorrow.
Even when remapping the channel nothing showed up, maybe the Arnold volume object is hardcoded to use standard names.

Offline paq

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Re: VDB workflow testing
« Reply #24 on: June 20, 2018, 01:45:11 PM »
Hi pokoy,

Here's the .vdb with the attribute renamed as density. The file is slightly bigger, I hope Houdini hasn't change anything else during the conversion :S
Gameloft

Online sboerner

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Re: VDB workflow testing
« Reply #25 on: June 20, 2018, 01:49:48 PM »
The cloud remains invisible to me as well. I'm testing it in Maya 2018 with Arnold and I am unable to assign a volumetric shader to it.

In the cloud's attributes panel only one channel, "Easy cloud 01," is listed under Grids and Velocity Grids. Other VDB files include several channels here with names like "density," "heat," etc.

Maya throws six errors when I try to assign the shader, two each for "Easy," "cloud," and "01." So I wonder if this might just be a naming issue since "Easy cloud 01" includes spaces.

82838-0

Size of the calibration chart on import is 100 x 100 meters, so that's off by a factor of 100. The FBX camera imports to the correction location.

Offline ajcgi

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Re: VDB workflow testing
« Reply #26 on: June 20, 2018, 01:53:01 PM »
Maybe try Paq's file there with the renamed attribute?

Online sboerner

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Re: VDB workflow testing
« Reply #27 on: June 20, 2018, 01:56:29 PM »
Quote
Maybe try Paq's file there with the renamed attribute?

Just saw that, thanks. I'll give it a try.

Edit: That did the trick. The cloud shows up in render view. I'll look at this tonight and will see if I can match the shadow rendering.
« Last Edit: June 20, 2018, 02:48:35 PM by sboerner »

Offline Matt

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Re: VDB workflow testing
« Reply #28 on: June 20, 2018, 07:52:32 PM »
I'm really pleased to see so much feedback already! Thank you all. I'll take a closer look this afternoon.  :D
Just because milk is white doesn't mean that clouds are made of milk.

Offline paq

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Re: VDB workflow testing
« Reply #29 on: June 20, 2018, 08:53:20 PM »
Hello,

So I'm trying to get a little bit of feedback from Clarisse users on the subjet :
https://forum.isotropix.com/viewtopic.php?f=5&t=4027

mdkai has some interesting remark about the shading, but I'm not really sure to follow, it's a little bit out of my range  8)
Gameloft

 

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