ShapeAn arbitrary curved shape which can be either flat (ribbon) or thick. Useful for modeling hair. The curve can be specified in various ways (Bezier, B-Spline, Catmull-Rom, etc.)
Describes how the curve is formed from the control points. Can choose from Bezier, B-Spline, Catmull-Rom, Linear.
Ribbon mode is recommended for fine geometry such as realistic hair, fur or fields of grass. These curves are rendered as camera-facing flat ribbons. For secondary and shadow rays, they face the incoming ray direction. This mode doesn't look so good for very wide hairs or dramatic zoom-ins because of the flat appearance. This mode works best with a proper hair shader (perhaps based on a Kay-Kajiya or Marschner specular model).
Thick mode resembles spaghetti. It has a circular cross section, and a normal vector that varies across the width of the hair. Thick hairs look great when zoomed in, and are specially useful for effects work, but their varying normals make them more difficult to antialias when they are small. You can use any shader with this rendering mode, including lambert, phong, etc.
If this value is non-zero, curves with a small on-screen width will be automatically enlarged so that they are at least the specified size in pixels. The enlargement fraction is then used in the hair shader to adjust the opacity so that the visible thickness of the hair remains the same. For a given number of AA samples, this makes it a lot easier to antialias fine hair, at the expense of render time (because of the additional transparency/depth complexity). Good values are in the range 0.2 to 0.7. Values closer to 0 are faster to render but need more AA samples. So if your scene already uses very high AA settings, you should use a low value like 0.1. For best results, you may need to increase the auto-transparency depth, and/or lower the auto-transparency threshold, but watch the effect on render times. Note that this parameter currently works with the ribbon mode only.
You can selectively disable an object's visibility for the various types of rays in the renderer. By default, objects are visible to all types of rays. Camera - Camera rays (i.e., primary or view rays). Shadow - Shadow rays fired in the direct lighting calculations. Reflected - Mirror reflection rays. Refracted - Refraction rays. Diffuse - Indirect diffuse rays (i.e. global illumination, hemi, or GI rays). Glossy - Indirect specular rays (i.e. glossy reflection rays).
Just like you can disable the visibility for specific ray types, you can also change an object's sidedness depending on the ray type. By default, objects are double-sided for all rays. By unclicking any of these checkboxes, the object will become single-sided, which means that those parts of the object whose normal vector points away from the incoming ray direction will not be rendered.
Determines whether or not the object picks up shadows from other objects.
Determines whether or not the object casts shadows on itself.
Invert normals (so that normals face inwards and not outwards).
Raytrace bias value specified for the object.
Transformation matrix. This can be either a single matrix or an array of matrices that define the SRT motion of the object for the current frame. (The matrices define the motion for the full frame, not just between the shutter open - close time.)
An array of nodes pointing to the shader or shaders in the case of per-face shader assignment.
The opaqueness (transparency) of the object. By default all objects are marked as opaque, because that speeds up the rendering considerably. Note that this flag is not set automatically by adding a transparent material to the object, it has to be set manually!
A boolean to enable selective light linking
An array of nodes pointing to the lights that will affect the node if use_light_group is enabled.
A boolean to enable selective shadow linking.
An array of nodes pointing to the lights that will not cast shadows on the polymesh, if use_shadow_group is enabled.
An array of strings each of which names a trace set. A custom shader must be used to make an effective use of these strings via the AiShaderGlobalsSetTraceSet and the AiShaderGlobalsUnsetTraceSet API calls.
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Unique ID for a node in the Arnold scene.