Has anyone here used Realflow Houdini plugins. How is exporting of mesh into RF's *.bin format from Houdini is done?
Ideally, I would like to bring in RF mesh sequence, append SOPs to it, then export the result as new RealFlow BIN sequence.
Also how can POP networks be exported into RF SD format.

DaveR

Hi David,

Houdini geometry is exported as RF SD files, animated or not. RF will only read it's own particle BIN format, it doesn't read mesh BIN files.

As far as importing RF mesh into SOP Land and adding more SOPs, it works, I do it all the time. If you want to export back to RF, use either the RF ROP or RF Export SOP.

As far as POP's, bring your POP data into SOP's, then export. I have considered releasing a RF Import/Export POP but haven't had enough time yet, still have much work to do on tutorials and adding/fixing a few more things with the current plugins.

Hope that helps. Let me know if you run into problems or identify a feature you'd like but is not presently implemented.


–Mark

Thank you mark. But

RF_Export_SOP does not really work. I don't know if its the SOP or RF or my use.

lets say I make a POPnet in Houdini. Then bring in the POP into Geometry via POPSOP. Then append RF_Export_SOP to POPSOP, and export with animated ON. All I am exporting are points. I cannot then bring that SD file into RF. It simply does not work.
I would like to bring Houdini particle sims into RF, generate the RF_Mesh in RF, and then bring that mesh into Maya. Giving me a Houdini -> Maya bridge.

Dave

DavidRindner
Thank you mark. But

RF_Export_SOP does not really work. I don't know if its the SOP or RF or my use.

Sorry, but I believe it's your usage as it's been working fine for a long time. Remember, it's meant to export triangular geometry only.

DavidRindner
lets say I make a POPnet in Houdini. Then bring in the POP into Geometry via POPSOP. Then append RF_Export_SOP to POPSOP, and export with animated ON. All I am exporting are points. I cannot then bring that SD file into RF. It simply does not work.

Right, this won't work, not because the plugin isn't operating properly, rather you're not exporting the proper geometry. RF doesn't have any way (yet) to import strictly point data, and if you think about it, you can't do any sims with just points, you need surfaces. So, turn your POP geo into spheres or something to your liking, append a convert SOP to turn the geo into tri-poly's, then export it to RF.

DavidRindner
I would like to bring Houdini particle sims into RF, generate the RF_Mesh in RF, and then bring that mesh into Maya. Giving me a Houdini -> Maya bridge.
Dave

That's definitely do-able. Also, remember that sometimes Houdini doesn't convert some geo into tri-polys correctly, sometimes this requires checking the data via a .geo file.

Hope this helps, let me know if you continue to run into problems.


–Mark

DavidRindner wrote:

I would like to bring Houdini particle sims into RF, generate the RF_Mesh in RF, and then bring that mesh into Maya. Giving me a Houdini -> Maya bridge.
Dave


That's definitely do-able.


OK, How do I do that? Becouse I am unable to make it work. How do I bring in Houdini POPSOP (particle points) into RF?

DR

DavidRindner
OK, How do I do that? Becouse I am unable to make it work. How do I bring in Houdini POPSOP (particle points) into RF?

Well, *one* way to do it is: create a POP network, in SOP land plop down a POP_Merge SOP and point it to the POP net you created. Put down a Sphere SOP and set it's geo type to polygon, size to something like 0.01, then append a Copy SOP to the Sphere SOP, and then connect the output of the POP Merge SOP to the second input to the Copy SOP. Append a RF_Export_SOP to the Copy SOP, point it to the location you want to write your SD file, then hit the “Write Real Flow SD File” button.

Now crank up RF and go to the object tab, open the SD file you just created and there you are! Just did it here and it works A-OK!


–Mark

Mark, I am sorry. The proccess, you described definatly does NOT work.
I have a POP network doing its thing over 177 frames. The # of points does change from frame to frame.
I brought into Geometry via POPMergeSOP. Created sphere (polygon) made of triangles. Stamped it onto the POP using CopySOP.
Appended RF_Export with animated (ON) and frame range set to 1 - 177.

Brought the SD file into RF 2.5.62. I get triangular junk all over the place.
I just need to bring in points into RF so i can create RF meshes.

DaveR

Hi David,

I'm sorry but it does work, don't have time at the moment to explain (I'm in a day long meeting), I will later this evening and create a test hip file for you.

Basically there's a restriction in Real Flow that the geometry (in an SD file) cannot change point/vertex count over time; please read the release notes a little closer.


–Mark

OK, I gathered as much prior. But I think I may not have made my needs clear. I don't need an SD file from Houdini. I need to export POP networks as RF compatible BIN files that I can bring in into RF as RealFlow Emitters. See what I mean. Ideally the points would carry their UVW texture coordinates and velocity vectors that would be translated into RF MotionBlur vectors. The surface mesh would be created in RealFlow. That surface mesh would be rendered through with Maya through Mental Ray. it would be loaded into Maya through RealFlow Mesh importer.

DaveR

Ahh, OK, now I see what you want to do, though from reading the previous posts I think you may be mixed up on a few points, let me see if I can help make it more clear.

First, if you'd like to make a “Houdini->Maya bridge” to get Houdini particles into Maya, why not just save out .obj files in SOP's and then import them into Maya?

Second, RF's BIN format is for both mesh and particles, but you can only import particles into RF with it's BIN loaders, I don't know if they plan to implement mesh BIN file imports.

What you mentioned in your last post about exporting RF particle BIN files from POPs is something I've thought about doing but haven't had the time yet, but if you (and others) really need this soon I suppose I could start working on it, though I'd rather finsih the rest of the work on the current set of plugins and I need to re-work all the tutorials.

May I ask is this for a “real” project or are you just “playing around” with RF/Houdini/Maya; I"m trying get a sense of your needs.


–Mark

I just joined a Maya shop that is bringing Houdini into its pipeline. My task is to make Houdini, Maya, RealFlow, Rush, and Mental Ray (farm) all work together for creation of liquid and particle effects. The shop's pipeline is solid when only Maya, RealFlow, Mental Ray, and Rushes are involved. I just need a bridge to get Houdini's particle data into Maya.
RealFlow and Maya work well together. Specifically RealFlow exports motion blur and UVW coordinates in its meshes, that are loaded through RF Loader in Maya.
Becouse of that I would like to use RF as bridge to bring in Houdini generated particle sims into Maya. For that I need a way to convert POPnets into RF bin files that come into RF as Emitters.

Simply exporting OBJ sequence is not a good solution as bridge between Houdini and Maya. For following reasons. Lets assume a POPNEt that has metaball stamped on it using CopySOP with resulting isosurface flow. If we export the isosurface as OBJ sequenece.
1. Even with MEL that imports the sequence and assigns Visibility keyframes to obj files, we get no motion blur or UVW information, as Houdini isosurfaces don't have the usefull kind of UVW that RF generates. So the frozen OBJ meshes from Houdini can only be used with materials that don't need UVW coordinates.
2. Even on machines with 2gb of ram, the amount of OBJ frame objects that can be brought in is very limited due to Maya's memory usage.
3. If we export POP_MErge_SOP to series of OBJ frames, those OBJs do not come into Maya, as Maya's OBJ import ignores point cloud data.

Now you did a great job of importing RealFlow's BIN format as particles, which gives us point cloud data in SOPs that is then used for stamping instances or metaball for isosurface gen, and can also be used for working I3d. What is needed is RF_Export_SOP that is appended to POP_Merge_SOP that exports Houdini's particle data into RF particle BIN file. I figure you know the BIN format, so it should be easy to covert point clouds into RF BIN particle files.

Dave Rindner

Hi Dave,

Thx for the info, it helps me to better understand.

DavidRindner
RealFlow and Maya work well together. Specifically RealFlow exports motion blur and UVW coordinates in its meshes, that are loaded through RF Loader in Maya.

According to the RF API, the only attributes contained in the RF mesh files are texture data and velocity, no motion blur (unless you're using velocity data to control motion blur)

DavidRindner
Simply exporting OBJ sequence is not a good solution as bridge between Houdini and Maya. For following reasons. Lets assume a POPNEt that has metaball stamped on it using CopySOP with resulting isosurface flow. If we export the isosurface as OBJ sequenece.
1. Even with MEL that imports the sequence and assigns Visibility keyframes to obj files, we get no motion blur or UVW information, as Houdini isosurfaces don't have the usefull kind of UVW that RF generates. So the frozen OBJ meshes from Houdini can only be used with materials that don't need UVW coordinates.
2. Even on machines with 2gb of ram, the amount of OBJ frame objects that can be brought in is very limited due to Maya's memory usage.
3. If we export POP_MErge_SOP to series of OBJ frames, those OBJs do not come into Maya, as Maya's OBJ import ignores point cloud data.

Hmmm … interesting limitations in Maya, what a drag.

DavidRindner
What is needed is RF_Export_SOP that is appended to POP_Merge_SOP that exports Houdini's particle data into RF particle BIN file. I figure you know the BIN format, so it should be easy to covert point clouds into RF BIN particle files.

Yea, I know the format well and can build this for you, it just a matter of time and money. Considering that the RF-Houdini project has been voluntary I can't dedicate as much time to it as I'd like, I have to make a living … :cry:

But on the other hand, the Houdini community is important to me and I'd like to address this need … let me give this some thought and see if I can get this done for you.


–Mark

Hello Dave,

OK, I can squeeze in a few hours over the next few evenings to do this, I can have it working hopefully by Friday, if not, Monday for sure.


Take care,
Mark

That is awosome. Thank you very much! I am curious though. The exporter would have to convert POP into RF compatible BIN. But to load those BIN's a compatible emittier would have to be created in RF first. I mean technically RF could be fooled by writing the BIN sequence into RF's project's Particle folder, emulating RF particle cache. Only in this case the cache is created by Houdini. But RF project would have to have a compatible emitter emmiter in project file to real that particle cache. How do you see that working?

DaveR

What I'll do is either add the particle export feature to the existing RF Export SOP, I may want create a new operator all together, not sure yet. This way the attributes you desire to have in the RF particle BIN file can be added using the various attribute SOPs preceding the RF Export SOP. That way you can map any data in Houdini to any attribute in the RF particle file. Sometime later I'll write some POP operators to handle RF data.

I may not be understanding your question about the emitter. After creating the RF particle BIN files, they can be loaded into RF with either the “Binary loader” or the “N-Binary Loader” which will bring the particles into RF.


–Mark

Hi Dave,

I wrote most of the BIN exporter and it's generating BIN files which I can read back into Houdini (via the RF_Import_SOP) and can dump their contents using the real flow particle “dumper” utility. However, when I try to load them into Real Flow with the BIN loader it locks up Real Flow bad. I've sent a note and some example files to Next Limit and hope to hear from them soon; as soon as I do I'll be able to make whatever changes are needed to finish this up. Shouldn't be too much longer.


–Mark

Cool! Very cool! THX.

My public e-mail is daverindner@yahoo.com
Please e-mail me the Houd. plug in. Even in its state.

One problem with RF I was recently experiencing is settling probliem. The system, regardless of drag force, always retains energy in it. But if you are doing pourable substances, say sand,sugar M&Ms, where the amount of rigid surfs are in tens or hundreds of thousansds, you want initial state to be perfectly settled. I.e. no velocity at all for any of particles in the system in its initial state. The BIN that RF writes out (single or sequence) retains velocity vectors for particles. This is good, but I just wish that I could write out a BIN, either out of RF or out of houdini (from imported RF bin) that has no energy in it. Just static particles, that would then naturally react to other RF forces.
I am no programmer, still I want to work with you and help you as much as I can, 'cause I am R&Dins ReaflFlow/Houdini integration right now.

Dave Rindner

Hey there,

OK, I've got the API problem figured out from Next Limit, there was a mysterious data field at the end of the BIN file called … it's used by Real Flow intrenally and can be ignored if importing BIN files, but needs to be set to 0's when writing the files.

There's still a few things to work out with the way the “node” transformations need to be dealt with (same is true in the SD file format) but the plugin will work as is.

DavidRindner
One problem with RF I was recently experiencing is settling probliem. The system, regardless of drag force, always retains energy in it. But if you are doing pourable substances, say sand,sugar M&Ms, where the amount of rigid surfs are in tens or hundreds of thousansds, you want initial state to be perfectly settled. I.e. no velocity at all for any of particles in the system in its initial state. The BIN that RF writes out (single or sequence) retains velocity vectors for particles. This is good, but I just wish that I could write out a BIN, either out of RF or out of houdini (from imported RF bin) that has no energy in it. Just static particles, that would then naturally react to other RF forces.
I am no programmer, still I want to work with you and help you as much as I can, 'cause I am R&Dins ReaflFlow/Houdini integration right now.
Dave Rindner

I'll be looking into this in more detail, please bear with me, it may take a few more days to get an answer from NL and find enough testing time, but we should be able to get answer and/or a work around soon.

(I'll post the new plugins in a few days for other RF users)


–Mark

Greetings,

I've got this feature incorporated now and will release it this weekend, just need to work on some sort of tutorial.

Dave, thanks for working on this with me and doing so much testing, it was a great help.

There's only a few more features to be added to the other plugins, and I should have the last remaing oddities of the RF API hammered out (with the help of Next Limit) before SIGGRAPH. So within a matter of 3-4 weeks the project will be ready for a “non-beta” release … finally! :-)

Whew! Now to find the time to have some fun with these new toys!


–Mark

Hi, sorry for my english but i use google translate.

I have to export from Houdini to Realflow, and I was wondering if things have changed today, or if they have simplified, or is everything the same as almost 20 years ago?

I downloaded Houdini 19 for free from the official website, but I am new to this software, can any of you help me please?

A thousand thanks.