Anyone have any experience in generating this kind of thing for Houdini? What's the “correct” way to go about it? Is that always done in post? I've seen plug-ins for Lightwave (Starpro) and wondered if there was something similar for Houdini, or is doing this stuff as part of the 3D render was not the way to go.

starfields and nebulah sounds like a great job for fractals and attractors. Which you can render as dense pointclouds with a program procedural (it's not too hard to write one in python that dumps points into the stream).

The main thing is to have the right kind of scale. You can also get away with rendering starfields as sprites. (for background) If you have to fly through some of it, you might want to go with volumes and some fancy shader.

Hi,

For a simple starfield, see Lesson 2, Part 4 of the following SESI tutorial:
http://www.sidefx.com/docs/houdini8/content/home.html [sidefx.com]

Cheers,
Greg

pclaes
starfields and nebulah sounds like a great job for fractals and attractors. Which you can render as dense pointclouds with a program procedural (it's not too hard to write one in python that dumps points into the stream).

The main thing is to have the right kind of scale. You can also get away with rendering starfields as sprites. (for background) If you have to fly through some of it, you might want to go with volumes and some fancy shader.

OK, this sounds like a cool approach, but having zero experience with this part of Houdini, any pointers as to where to begin? Is there a tutorial anywhere that covers some part of this?

Have a look here:
http://hosok2.com/project/helper/helper.htm [hosok2.com]

It is mostly using renderman, but the workflow is very similar for houdini.

The way I started it was having a look at how a “.geo” file is saved (with only a bunch of points inside. - eg: save the geometry of a line to a “.geo” file. and then open it up with a text editor (because .geo is just the asci version of the binary .bgeo).

You can then write a python script that dumps points into the ifd stream for you. (since you are basically writing a .geo file on the fly, you could also save it out to disk and load it back into houdini if you wanted to ).

In regards to the kind of patterns you can generate have a look here:
http://local.wasp.uwa.edu.au/~pbourke/fractals/ [local.wasp.uwa.edu.au]

This one I did based on a Clifford attractor (using the renderman python api) - but I recently also did it again in houdini with a mantra program procedural:
http://www.peterclaes.be/video/pca_0032.avi [peterclaes.be]

You could also fake it a bit with noisy geometry and an x-ray shader:
http://hosok2.com/project/bird/bird.htm [hosok2.com]


In terms of the volume rendering, you need to have a spike in your ramp that drives the density. Something similar to this kind of ramp (the top one):
http://schizoslayer.co.uk/wp-content/uploads/2009/02/497ebb8bb18268cacead6ffad11abb5f.png [schizoslayer.co.uk]

Ohh…perhaps somewhat old thread this is, anyway..

I can´t see why the same techniques couldn´t be used for houdini as to those I used in lightwave for these..
Sorry I posted them as bmp format..

http://www.newtek.com/forums/attachment.php?attachmentid=89588&d=1288899614 [newtek.com]

http://www.newtek.com/forums/attachment.php?attachmentid=89587&d=1288899585 [newtek.com]

http://www.newtek.com/forums/attachment.php?attachmentid=55118&d=1203911813 [newtek.com]

Mostly hypervoxel sprites, and the first is a mix of sprites and volumetric lights with procedural textures, to get some more whispy detail in, theres procedural displacement textures underneath the main procedural texture.

all sprites and volumetric lights in sprite mode…stars is sprite clip images with pre-rendered lens flare.

I would love to see some pics of nebula made from houdini people thou.

With houdinis capabilities to create volumetric implicit surfaces for volumetric objects and now houdinis fluid and pyro tools should be able to create a static fluid sim and use as a nebula

Michael

Just as an FYI, the links you posted don't result in pictures, they're blocked unless you're a member of the newtek forums.

Ohh crap..I forgot, I tested the link, but I was logged in, should have known this of course, Im sorry.

here´s the pics..

I hope I can figure out the houdini way to do this similar, Im suspecting it takes much more setting up thou, and doesn´t have the huge procedural collection as lightwave does thou.

renders very fast, and I just recently installed the new lightwave 10 build with it´s VPR I get to see and tweak this Almost in real time in the viewports.

I was trying to get into Houdini maybe some year ago, but the machine I had was faulty and was freezing every now and then so I gave up at that time, now with my new computer and freshly installed lightwave 10 and houdini, Im not sure where to spend the time, both software are so nice you know..depending on what you do.


Michael

Wow, those are all rendered? They look beautiful! While I'm sure you could do this in Houdini, the little I've played with volumetric lighting suggests that something like this would take quite a bit of time to render.

jimc
Wow, those are all rendered? They look beautiful! While I'm sure you could do this in Houdini, the little I've played with volumetric lighting suggests that something like this would take quite a bit of time to render.

Yepp all lightwave 9.6 renders, approx 5.6 seconds 600x1000 resolution for sample 2, I don´t even get mantra in houdini started to render in that
time, and add the time I have to set up a render node too..in lightwave just hit f9..just one of those workflow things I don´t like with houdini.

with Hv sprites 1 single null voxel, 2000 particles for stars and sprite clipmaps on those, 3 lights with lensflares and volumetric lights activated, the volumetric lights has a sprite mode so that´s why they render fast, and they have procedural textures activated as well.

Thats for sample 1 and 2, the other collection is mostly sprites, and maybe one or two volumetric hypervoxels, but those were slower.

Now In lightwave 10 and VPR I get to see those almost in real time, I don´t think I can show that off yet on a vimeo page, since It officially isn´t out yet, q4 this year is the shipping date.
viewing hypervoxels volume mode in VPR is absolutly Awesome ..almost realtime, Rob Powers who worked with Avatar and now working with newtek showed a nice video on that.

Im sure that even more mind bogglig images can be created through Houdini thou,because of It´s node structure.
The problem Is the steep learning curve thou, and acessing and tweaking sprites doesn´t come close to how fast it works in lightwave.

Michael

Here's a 5 minute prototype thrown together. It uses a Volume VOP SOP and a Volume Visualization SOP to do the most work. Using four fields: Density as the opacity mask and Cd (Cd.x, Cd.y, Cd.z) volumes to visualize the final color.

One thing to add is a density field that is generated from some modeled geometry and converted in to a fog object via Iso Offset SOP instead then multiply the Cd channels by the density to get your proper density mask as is done in DOPs.

To increase feedback, you could crop the volumes feeding in to the Volume VOP SOP by copying the fields in to a smaller same resolution volume.

Lots and lots of possibilities here and this is just a bare bones set-up. Just keep on working on the Volume VOP SOP to add more and more detail. You could add point clouds for stars and local illumination and more and more. Build your own nebula tool.

And this isn't even considering the option of merging in other volumes of varying density. For example, you could copy small volumes to particles and then merge them in to this volume (Volume Merge SOP of course) and work some more in another Volume VOP SOP to mix them in at will.

Wow!

The viewport looks every bit as good as mantra so might as well render the viewport out.

—-

After using the latest Volume based SOPs and the new volume compression options, I can't think of using sprites or meta-balls as volumes for these sorts of things any more. Nope. No more sprite hacks in Houdini. Now volume hacks.

Very, Very nice!!!

Could someone post some pics of this? I tried to open this in Houdini 10, but I got a boatload of warnings, and I'm not sure the mantra render was really what was intended. Thanks! Is this usable in Houdini 10, or do you need Houdini 11 to open it correctly?

cool..but not as nice and interactive to tweak for immidiate respons, I sure wish there was a viper type of preview renderer in houdini for this stuff.

Thanks for the scene,interesting to learn other techniques than Lightwaves voxels.

to much of blurry fields in the basic setup, I would like to get whispy undulations in there, I was trying changing roughness and frequencies in the volume vop, but I havent learned how two tweak it to my liking yet.

fog objects like this can´t, nativly be done in lightwave, so this is interesting.


Michael

Very nice images.. can't wait to see what houdini can do.

The lightwave ones sure look familiar to me, having watched many 80's/90's TV scifi shows

jimc
Is this usable in Houdini 10, or do you need Houdini 11 to open it correctly?

Houdini11 has all the new Volume based SOPs so you will get errors loading in to H10.