Krakatoa *.bin files

[Bobo]

Hi guys,

I'm exporting particles from Houdini using realflow bin format to render them in krakatoa.
I'm having problems with the krakatoa loader. I can see all the particles in the viewport but they don't render.
Also, if I use a NL particle loader, krakatoa can't render the particles with motion blur, but scanline does.

Any suggestion?

Thank you,

Miguel.

Hola Miguel,

If you open the Krakatoa Log, does it say that it DID render any particles? (There should be a count of particles loaded). If it does say so, then your particles are most probably rendering with wrong density (possibly 0). Try unchecking the "Scale Density by Material Opacity" option in the Main Controls rollout and see if they will appear. Also play with color override, bump up the Density per Particle to very high exponent values and watch the Alpha channel of the rendered bitmap for any particles that might be there but invisible...

If you still have troubles, please post here.

When using the NL BIN Loader, do you try to render the vertices of the resulting mesh as particles? Krakatoa's internal motion blur is based on particle velocities. AFAIK, Krakatoa does not get velocities from vertices yet. Using the MultiPass Motion Blur Camera Effect in the Max camera, while slower, should catch that and give you Krakatoa rendering with Motion Blur of the NL BIN Loader.

Writing a PRT file exporter for Houdini might be worth it. Btw, the PRT File Specs are public (http://franticfilms.com/software/support/krakatoa/prt_file_format.php) and anyone can implement support for the format. It is much more straight-forward than BIN.

[MiguelPerez]

Hello Bobo, thanks for replying.

The log says that krakatoa is rendering the particles. And with a density of 5000, exponent +30, custom particle color and the "Scale density using material opacity" unchecked, there is nothing in the render, not even in the alpha chanel.
If in the same scene I add other particles (pflow, ln particles) they render perfectly.

I've uploaded a bin sequence exported from houdini to see if you have the same problem.
http://www.miguelperezsenent.com/Etc/binseq.zip

When using the NL BIN Loader, do you try to render the vertices of the resulting mesh as particles?

Oh! It's true, they are not particles... silly me

[Bobo]

Hello Bobo, thanks for replying.

The log says that krakatoa is rendering the particles. And with a density of 5000, exponent +30, custom particle color and the "Scale density using material opacity" unchecked, there is nothing in the render, not even in the alpha chanel.
If in the same scene I add other particles (pflow, ln particles) they render perfectly.

I've uploaded a bin sequence exported from houdini to see if you have the same problem.
http://www.miguelperezsenent.com/Etc/binseq.zip



Oh! It's true, they are not particles... silly me

Hi again, Miguel.

Yes, it IS a density issue. For some reason, (most likely because the BIN files contain some empty channel called "Density"), Krakatoa sees the BIN file as containing density of 0.0. Since we use only SCALING of density (in other words, all options to change the Density are multiplicative), if the initial value is 0.0, you always end up with 0.0 no matter how hard you try.

I have some Good News.

First, you can easily fix this using the version of Krakatoa you have:

*Create the Loader and load the original sequence.
*Open the Channels To Save rollout (available since v1.0.1.29090) and REMOVE the Density channel from the list of channels to save
*Set Krakatoa to Save Particles To File Sequence and write out to a new sequence - I even wrote out to RealFlow 4 BIN files again, in case you ever wanted to move the files back to Houdini. It is recommended to write to PRT though - it is faster to read and MUCH smaller (frame 100 of the BIN is 160KB, same frame is 26KB as PRT thanks to the Zipping of the content).
You can also remove the Normals and Color channels because the source BIN does not contain any normals or colors. Leave Position and Velocity. Removing channels really removes them from the PRT making it even smaller, while the BIN always has a fixed channel structure - yet another reason to use PRT.

Now you can replace the old BIN files with the new file sequence - since it does not contain any Density data, Krakatoa will assume the Density to be 1.0 and it will render as usual. Rotate the PRT Loader to match the Z up coordinates and you will have your falling sand.

Of course, 1500 particles is surely not something you would need Krakatoa to render, but I assume it was just a technical test. Try 1.5 or 15 million ;)

The other Good News - in the upcoming 1.1.0 update, there will be a checkbox in the PRT Loader which lets you reset the incoming density to 1.0 regardless of the file content. I tried your sequence in a Beta of that version and checking the box fixed the issue immediately.

Also, we are working on a set of new Particle Flow operators that can read and play back dynamic sequences (incl. dynamic birth and death of particles). I loaded your sequence using the prototypes of these operators and it played back and rendered in Krakatoa perfectly.

So for now we have a workaround for you, in the future it shouldn't be an issue at all.

[MiguelPerez]

Thanks! This is great!

Of course, this was only a test :)

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