Houdini and ZBrush

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Houdini 11 and ZBrush 4

Video tutorial by Peter Quint at vimeo.com.

Houdini 10

Use the displacement material form the H10-shader-bar.

Houdini 9

Download the shader-archive from 'Houdini Exchange' and install the OTL from the H9-directory. Follow the instruction in the part about Houdini7/8 above.

Houdini 7/8: Basic workflow

Create your poly-model in Houdini.
Export the model in OBJ-format (left click on the last SOP-operator and use in the context-menu 'Save Geometry...')⁽¹⁾.
Start ZBrush and import the OBJ-file ('Tool/Import').
Set the obj into the scene and switch to edit-mode (click on 'Edit'-button).
Subdivide the model (up to level 4 to 6) and detail the geometry in ZBrush.
Set the 'SDiv'-factor back to level 1 ('Tools/Geometry').
Open the 'Displacement'-option in 'Tools' and click the 'Adaptive'-button⁽²⁾. Hit the 'Create Displacement'-button. Wait for ZBrush...
Select the new map in 'Alpha' and change the map with 'Flip V' ⁽³⁾ and export the image with the 'Export'-button (use TIF-format).
Export the detailed geometry in OBJ-format: Use the button 'Tool/Export'.
Change the OBJ-extension to lower case.
Start Houdini, add a geometry-operator and enter the SOP-level.
Add a file-SOP and set the path to the OBJ-file from ZBrush.
Switch to the shaders (SHOP) - open the palette-window (Alt+g or menu 'Tools/Shader Palette ...').
Switch to the directory with the 'VEX_ZBrush_Displacement.palette' - import the shader for the displacement-map (use 'Drag&Drop').
Open the option for the new shader and enter the location for the by ZBrush generated displacement-image - 'D-Map (ZBrush)'.
Go back to the SOP-level and add a shader-SOP to the network. Select in the option-pane (press 'P') the new shader in the 'displacement-field'.
Add a subdivision-SOP to the network.
Render the scene. Refine the displacement-level in the shader-option-pane if necessary and re-render.

⁽¹⁾ Make sure there are no N-gons (polys with more than 4 sides) in the geometry. ZBrush will show a warning if there are n-gons in the geometry and convert this to quads and tri-sided polys.

Don't use this way - expect render-artifacts (check this picture).: A Model with a n-gon (left) will be converted to tri-sided polys by ZBrush (middle) - this geometry will cause render-artifacts in Houdini (right).