Houdini plugin - Camera and object parameters

Owned by
Peter Horvath (Unlicensed)
Last updated: 24 Jan, 2015
4 min read

Camera

Each camera node defined in the scene and marked as rendered will be translated to Maxwell Render by the plug-in, same way as the other renderers (like Mantra) work.

Basic camera parameters such as shutter speed, f-stop or position, rotation, uv coordinates are read from the Houdini camera node itself (see Maxwell Camera (OBJ)). In addition Maxwell has some specific parameters which are not available on Houdini’s default camera node. These can be defined with the Maxwell Camera Params node on the OBJ level which expects the camera node as the input.

Maxwell Render simulates a real camera with the associated lens set, diaphragm, etc. parameters. Special camera parameters are the following:
  • Exposure: presets of commonly used interior and exterior exposure settings. You can define any custom values in Custom mode.
  • Lens: specifies the type of the camera lens. Maxwell Render provides 6 different lens types useful for a range of different scenarios. For more details on the camera lens type, please check the Camera Lenses page.
  • Aperture: specifies the projection angle for Fish Eye, Spherical and Cylindrical type lenses.
  • Use Shutter Speed: camera shutter is different in Houdini and Maxwell. Houdini stores shutter time in 0 – 1 interval, while Maxwell uses shutter speed. Shutter time is translated with a formula (described in the Maxwell Camera section) which has some limitations. If this flag is turned on, the given value will be used as the camera shutter speed in the Maxwell scene.
  • Shutter Speed: specifies shutter speed value of the Maxwell camera.
  • ISO: specifies the film's light- sensitivity. Higher ISO is more sensitive.
  • Response: presets of different real camera curve response settings.

  • Use Rotary Shutter: enables the rotary shutter mode, which mimics the behavior of a film cameras shutter. In this mode the shutter time value is overridden with the value computed from the angle.

  • Shutter Angle: defines how long the film is exposed to light: 90 degrees means that the shutter time is a quarter of the frame time, while a value of 360 degrees means there's no shutter at all and the film is exposed for the whole duration of the frame.

  • Shift Offset: specifies the offset of the lens position horizontally and vertically which can be useful to correct geometric perspective distortion.
  • Aperture: controls the shape of the “bokeh” effect caused by bright spots in the parts of the render that are out of focus. (Circular or Polygonal)
  • Blades: specifies the number of blades for Polygonal diaphragm.
  • Angle: specifies rotation angle of aperture opening for Polygonal diaphragm.
  • Custom Bokeh: enables anamorphic bokeh, allowing you to get a natural anisotropic non-round bokeh.
  • Bokeh Ratio: specifies the aspect ratio of the anamorphic bokeh.
  • Bokeh Angle: specifies the angle of the anamorphic bokeh.

Object

Each geometry node defined in the scene and marked as rendered will be translated to Maxwell Render by the plug-in, same way as the other renderers (like Mantra) work.

Basic geometry parameters such as position, rotation, uv coordinates are read from the node, but Maxwell objects has some specific parameters which are not available on Houdini’s default geometry node. These can be defined with the Maxwell Object Params node on the OBJ level which expects the geometry node as the input.

Maxwell related object settings are the following:

  • Opacity: specifies the opacity of the object.
  • Object ID: specifies the color to identify the object.
  • Backface Material: allows you to map a separate material to the reverse face of a polygons of the object. Read more...
  • Boolean: turns the object to a render boolean, which is an object used to cut other objects in the scene. Read more...
  • Blocked Emitters: specifies the list of lights and emitters which are not lit the object in the render. The plug-in translates Houdini’s light linking setup as blocked emitters.
  • Recalculate Normals: recalculates normal vectors for each vertex when the geometry is translated to Maxwell Render. When this flag is turned off then the plug-in tries to find and use the normal vertex or point attribute associated with the geometry. When the geometry has no normal attribute, then calculates normals from the primitives.
  • Smoothing: the angle of smoothing used when the normals are recalculated by Maxwell.
  • Geometry Vertex Blur: deformation blur if calculated from the position of the vertices if enabled. It can be useful by changing topologies which have no velocity attributes defined.
  • Hidden From Camera: specifies visibility of the object.
  • Hidden From Camera in Shadow Channel: specifies visibility of the object in shadow channel.
  • Hidden From Reflections/Refractions: reflected or refracted objects are hidden.
  • Hidden From Global Illumination: the object will render but will not affect lighting.
  • Hidden From Z-clip Planes: if this option is selected, the object won't be cut by Z-clip planes.