Hello, on the Vray4houdini page of chaosgroup website we can read :
VOLUME RENDERING Fast and accurate rendering of native Houdini volumes and OpenVDB caches.
My english isn’t 100% accurate, but for me it’s mean that i can render fire and smoke like i do in Mantra or redshift. using the bgeo.sc cache files i’ usually do not ?
so, i create my fire and smoke with Pyro, i assign a material with Vray-phxShaderSim. in parameter i setup Houdini fire/smoke then i fill the Fields with the correct temperature density etc attributs.
I’m trying to render .. nothing appear.
I check in rendering parameters in OUT context. i see a probabilistic volumetrics, i try to see if if’s change something but not.
How to render native Houdini Volumes ? needs help. thanks you.
Hello @ghiom3d , you can use houdini`s native File or FileCache SOPs to load vdbs. VolumeGrid Cache SOP works only with aur files /ChaosGroup Phoenix FD cache files/. Looks like we are forgotten to update the docs page.
thanks you @chakarov looks like i can use the bgeo.sc cache right now instead of a vdb sequence.
Physicaly Based set to 0 make it very bright.
Physicaly Based set to 1 make it fully black.
It’s like opposite than what i see on documentation. and 1 > flame are black look like a error to me not ?
inb doc we saw that physically 1 make it more bright than 0 and in my case it’s inverted.
the Physically Based option expects real-world temperature values, so a good start would be to remap the heat or temperature field to values between e.g. 800 and 3000.
For instance, using a Volume Wrangle, you could
f@heat = 800 + fit(@heat, 0, 2, 0, 1200);
This should give you the expected behavior.
We’re currently working on adding information guides on major features so such information is readily available.
Hi thanks you @Gosho.Genchev . DOn’t know if it’s the nightly build or i misunderstand something.
I add the volume wrangle node after my cache file. i change heat by flame because it’s the name of my attribut in my case.
now it’s look thousand times too much bright. so i put physically based at 1 and i see better my fire. but i loose the colors of the flame. it’s very long to render, it’s not nice.
In the doc, when we change physically based from 0 to 1 , we add a lot of power in the fire. HEre, it’s not the case, we have a powerfull fir at 0 and many less one at 1.
