Hi, im really new to Houdini. Im working on a personal project, the simulation is fine, the materials are ready, but when i render with mantra, is not showing what the viewport shows. Please help me, dont know if im doing the mantra node wrong or the materials…

Here are images of the viewport and the final render.

Your viewport screenshot looks like an SDF volume of some kind. To render an SDF as an isosurface directly, custom render properties are required.

• vm_volumeiso (True)
  
• vm_volumedensity (0)
  

However, rendering an isosurface is often much slower than polygons. Why not convert to polys first?

jsmack
Your viewport screenshot looks like an SDF volume of some kind. To render an SDF as an isosurface directly, custom render properties are required.

• vm_volumeiso (True)
  
• vm_volumedensity (0)
  

However, rendering an isosurface is often much slower than polygons. Why not convert to polys first?

Thanks for replying, but as i said, im a total noob with this software. The mesh in viewport is a skull i did on Zbrush, and i was trying the “Suction Fluid” to suck the black liquid. So i had to modify the Voxel Size of the mesh to actually see details when the suction is done. Its like this tutorial: https://www.youtube.com/watch?v=goyiEITdHvs&t=214s [www.youtube.com]

But the real problem is the render, as you saw, the skull is black, when should be white (modified white porcelain mantra material). Thanks again.

Long version of the first approach jsmack described:

If you go up in the network editor to the object level, if you select the object node containing the skull, (which is apparently a Signed Distance Field VDB volume, not a polygon mesh), there's an icon above the parameters that looks like a gear. If you click it, there's an option “Edit Rendering Parameters…”. In there, if you type “vm_volumeiso” in the Filter box and hit Enter, it will limit the set of rendering parameters shown, so that you can easily select the “Volume Isosurface (vm_volumeiso)” option, press the button with the icon pointing right, then type “vm_volumedensity” in the Filter box and hit Enter, select “Volume Density (vm_volumedensity)”, press the button with the icon pointing right again, then press Accept. Then, find those parameters in the parameter pane for the node under the Sampling tab under the Render tab and turn Volume Isosurface on and set Volume Density to 0. This tells Mantra to treat the volume as just the surface where the value crosses zero, and to not treat it as a true volume. (This should probably be the default behaviour for SDF volumes, but isn't currently; sorry!)

Long version of the second approach jsmack described:

If you dive down in the network editor into the object containing the skull, there'll be a node somewhere with a big blue and purple circle behind it and a section of the node will be blue. This is the displayed node. Click on the output of that node, then hit Tab, type “ConvertVDB”, and hit Shift+Enter (this creates the node and moves the display flag; Enter just creates the node). Change “Convert To” to “Polygons”. Now, the VDB volume is converted to polygons and should render as polygons, instead of as a volume.

Hopefully that gets you what you need, and feel free to ask any more questions you might have along the way! Sorry that the paragraphs above are pretty verbose; describing UI clearly in text is tough.