Deborah R. Fowler
Houdini Lighting - Solaris/Karma
Posted Dec 2 2019
Updated on Dec 8 2019
Render Basics - Karma
Assigning a shader (desktop Solaris view):
http://www.sidefx.com/docs/houdini/nodes/lop/assignmaterial.html
To assign a shader to your object use can use the
assignmaterial node (also called a lop) or the materiallibrary
lop.
This assumes you are in the lopnet (or stage) context and you
have set up your scene for lighting using USD. You will also need
an available material.
materialibrary - to create materials, dive inside
this node - you can copy them from the /mat context or tab create,
for example principled or classic.
Option 1: Click Auto-fill Materials. Drag your mesh to the
geometry path.
Option 2: Use the assignmaterial by dragging the mesh you
want to assign to the primitive and dragging the material from the
Scene Graph Tree.
ADVANCED TIP: Similar to
Mantra, you can override properties of the classic shader.
In this case you create a vexpression and bind it to the
parameter. You must promote the parameter first.
This also works with the principledshader but the property is
basecolor not diff_color.
To promote a parameter
Shadows:
- you can use shadow color (this really should be
defined by the fill lights, but may in some cases want to add a
wee little touch of color - for example (.01,.007, .01)).
- Parameter was added as of H12.5 and up and exists in H18
- This parameter is useful for two things:
- when the lighting is perfect but the shadow is a bit drab or dingy
- when you are debugging - crank it up to red for example (less useful now that we can easily use the lightmixer to disable and solo lights.
Lightmixer: allows you to manipulate lights easily,
including solo and disable - there is also a sheet tab if you have
many many lights (similar to the old data tree)
In the figure I have two rules, one enabled to turn the light off of the sphere.
see also H18 Launch Presentation at timestamp 28:02
Shadow masks - can do this in the lightlinker ALT drag the lights into the middle to get the shadow linking properties (it will appear purple rather than gray)
Render Nodes - Karma settings
For the preview render in the viewport, you can hit d
and it will bring up the options. For quick preview set samples
to 2.
TIP: remember to create your render folder AND to specify your
Images/Output Picture (it defaults to ip which does not work)
For an actual render - note the karma lop (node). Specify where you want to save the image and then click Save to Disk. This will create your rendered image (a process husk.exe is run)
NOTE: you must create your render folder manually as of
H18.0.287 unlike mantra which creates it for you automatically
TIP: create your render
folder AND to specify your Images/Output Picture (it
defaults to ip which does not work, but you can use the dropdown
menu)
