Rendering Options

Element type: miSCENE_OPTIONS
Data type: miOptions
Sizes: -
Defaults: as described below

The rendering options were designed to accommodate as wide a range of renderers as possible, from simple wireframe displayers to complex ray tracers. The interpretation of the structure members is left to the renderer. Generally, no renderer will require all provided fields; each renderer may use a different subset.

struct miOptions {
        miBoolean       trace;                  /* 2nd generation ray trace? */
        int             scanline;               /* one of miRENDER_FH_* */
        miUint          motion;                 /* motion blur? : miFALSE */
        miBoolean       shadow_sort;            /* Obsolete! Do not use */
        miBoolean       preview_mode;           /* for future use */
        int             reflection_depth;       /* refl. trace depth : 1 */
        int             refraction_depth;       /* refr. trace depth : 1 */
        int             trace_depth;            /* refl. + refr. depth : 1 */
        int             min_samples;            /* min. sampling level : -2 */
        int             max_samples;            /* max. sampling level : 0 */
        miColor         contrast;               /* sampling contrast: .1 */
        miColor         time_contrast;          /* temporal sampling contrast*/
        miTag           contour_contrast;       /* NULLTAG */
        miTag           contour_store;          /* NULLTAG */
        miBoolean       caustic;                /* enable caustics: miFALSE */
        miBoolean       globillum;              /* enable global il.: miFALSE*/
        int             caustic_accuracy;       /* no. caus. photons in est. */
        float           caustic_radius;         /* maxdist for caus. photons */
        int             globillum_accuracy;     /* no. glob. photons in est. */
        float           globillum_radius;       /* maxdist for glob. photons */
        float           caustic_filter_const;   /* filter const. for caus. */
        float           filter_size_x;          /* filter size in x : 1.0 */
        float           filter_size_y;          /* filter size in y : 1.0 */
        float           jitter;                 /* sample jittering : 1.0 */
        float           shutter;                /* shutter close time: 0 */
        short           grid_res[3];            /* grid resolution */
        short           grid_max_size;          /* max obj. in grid cell */
        short           grid_max_depth;         /* max grid nesting */
        miSint1         def_min_samples;        /* min/max samples for objs */
        miSint1         def_max_samples;        /* without min/max, -128 127 */
        int             space_max_size;         /* space subdiv. leaf size: 4*/
        int             space_max_depth;        /* space subdiv. depth : 25*/
        float           shutter_delay;          /* shutter open time: 0 */
        int             no_images;              /* # images : 1 */
        miApprox        approx;                 /* approximation overrides if*/
        miApprox        approx_displace;        /* style != APPROX_STYLE_NONE*/
        miUint          spare1[19];             /* keep ray33 offsets */
        miTag           images_info;            /* frame buffers */
        miTag           finalgather_file;       /* finalgather map file: 0 */
        miCBoolean      space_shadow_separate;  /* space subdiv shadow struct*/
        miUchar         finalgather_filter;     /* finalgather ray filter */
        char            rast_collect_rate;      /* rasterizer only: */
                                                /* samples per pixel dim. */
        char            rast_motion_resample;   /* rasterizer only: # of */
                                                /* time samples for movng geo*/
        char            use_shadow_maps;        /* 0=off, 1=on, 'o'=opengl*/
                                                /* bit7: only shmap,no render*/
        miCBoolean      rendering_shadow_maps;  /* Shadow map mode? 0 */
        char            recompute_shadow_maps;  /* 'n'o,'y'es (could be Bool)*/
        char            shadow;                 /* shadow casting? : 1 */
                                                /* 0 off, 1 on, 'l' sort, */
                                                /* 's' segments */
        char            caustic_filter;         /* filter-type */
                                                /* 'b' box, 'c' cone, */
                                                /* 'g' gaussian */
        miCBoolean      finalgather_rebuild;    /* rebuild FG ?: on*/
        char            filter;                 /* sample filter type : 'b' */
                                                /* 'b' box, 't' triangle, */
                                                /* 'g' gauss */
        char            acceleration;           /* one of miRENDER_ACCEL_*   */
        char            face;                   /* primitive facing: 'a' */
                                                /* 'f' front, 'b' back, */
                                                /* 'a' all */
        char            field;                  /* field rendering? 0 */
                                                /* 0 off, 'e' even, 'o' odd */
        char            smethod;                /* sampling algorithm: 'q' */
        char            render_space;           /* coordinate space 'o' */
                                                /* 'c' camera space, */
                                                /* 'o' object space, */
                                                /* 'm' mixed space */
        miCBoolean      pixel_preview;          /* pixel selective sampling */
        miCBoolean      task_preview;           /* task selective sampling */
        miCBoolean      visible_lights;         /* any visible area lights? */
        miCBoolean      shadow_map_motion;      /* motion blurred shadowmaps?*/
        int             task_size;              /* image task size : 0 */
        miBoolean       strips;                 /* GAP returns triangles in
                                                 * strips */
        miTag           photonmap_file;         /* photon map file name */
        miBoolean       photonmap_rebuild;      /* photon map rebuild ? */
        int             photon_reflection_depth;/* photon refl. depth */
        int             photon_refraction_depth;/* photon refr. depth */
        int             photon_trace_depth;     /* total photon trace depth */
        int             space_max_mem;          /* maximum bsp memory (mb):0 */
        miColor         caustic_scale;          /* caustic multiplier */
        miColor         globillum_scale;        /* globillum multiplier */
        miColor         finalgather_scale;      /* finalgather multiplier */
        miColor         finalgather_sec_scale;  /* secondary fg multiplier */
        miUint          spare4;
        miColor         photonvol_scale;        /* photon volume multiplier */
        miUint          spare2[6];              /* keep ray33 offsets */
        miTag           spectrum_blueprint;     /* spectrum for render space */
        miTag           input_cprof;            /* input color space, default */
        miTag           white_cprof;            /* white adapt. col. space */
        miTag           render_cprof;           /* color profile render space*/
        miTag           fb_dir;                 /* frame buffer directory */
        miCBoolean      no_lens;                /* disable lens shaders */
        miCBoolean      no_volume;              /* disable volume shaders */
        miCBoolean      no_geometry;            /* disable geometry shaders */
        miCBoolean      no_displace;            /* disable displace shaders */
        miUint1         no_output;              /* disable output shaders */
        miCBoolean      no_merge;               /* disable surface merging */
        miUint1         caustic_flag;           /* def. caustic flag for objs*/
        miUint1         diagnostic_mode;        /* miSCENE_DIAG_* flags */
        int             photonvol_accuracy;     /* no. vol. photons in est. */
        float           photonvol_radius;       /* maxdist for vol. photons */
        miUint1         globillum_flag;         /* def. globil. flag for objs*/
        miCBoolean      samplelock;             /* steady samples?: on */
        miCBoolean      autovolume;             /* internal volumes? */
        miCBoolean      finalgather_view;       /* radii in raster pixels ? */
        miCBoolean      no_hair;                /* disable hair rendering */
        miUint1         n_motion_vectors;       /* global number of motions */
        miCBoolean      no_pass;                /* disable multipass render */
        miCBoolean      photon_autovolume;      /* autovolume for photons */
        miCBoolean      no_predisplace;         /* disable displ presampling */
        miUint1         fg_reflection_depth;    /* finalgather refl. depth */
        miUint1         fg_refraction_depth;    /* finalgather refr. depth */
        miUint1         fg_trace_depth;         /* total fg trace depth */
        float           fg_falloff_start;       /* finalgather falloff start */
        float           fg_falloff_stop;        /* finalgather falloff stop */
        miTag           userdata;               /* optional user data blocks */
        miBoolean       irradiance_particles;   /* irradiance particles on/off */
        miUint4         spare5[23];             /* not used, but keep offsets */
        int             finalgather;            /* 0:off,1:on,'f':fastlookup*/
        int             finalgather_rays;       /* no. rays in final gather */
        float           finalgather_maxradius;  /* maxdist for finalgather */
        float           finalgather_minradius;  /* mindist for finalgather */
        float           diag_photon_density;    /* density for diag */
        float           diag_grid_size;         /* gridsize for diag */
        miBoolean       desaturate;             /* for IMG: fade to white? */
        miBoolean       dither;                 /* for IMG: LSB dithering? */
        miBoolean       nopremult;              /* for IMG: A < rgb="" ok?="" */="" int="" colorclip;="" for="" img:="" miimg_colorclip*="" */="" float="" gamma;="" for="" img:="" gamma,="" default="" 1="" */="" mitag="" inh_funcdecl;="" inheritance="" function="" */="" micolor="" luminance_weight;="" weights="" to="" calc="" intensity="" */="" int="" spare0[2];="" not="" used="" */="" micboolean="" inh_is_traversal;="" inh_funcdecl="" is="" a="" traver-="" */="" sal,="" not="" inheritance,="" shd="" */="" miuint1="" hardware;="" hwrender="" 0="off" 1="on" 3="all" */="" miuint1="" hardware_diagnostic;="" flags="" for="" diagn.="" mode="" */="" miuint1="" shadowmap_flags;="" flag="" for="" shadowmaps="" */="" float="" maxdisplace;="" override="" if="" !="0:" default="" 0*/="" miscalar="" shadowmap_bias;="" move="" shmap="" z="" back="" by="" bias="" */="" miuint1="" hwshader;="" 1="force" */="" 2="cg" 4="oglsl/hlsl" 8="fast" */="" micboolean="" photonmap_only;="" render="" photon="" map="" only="" */="" miuint1="" lightmap;="" 0="off,1=on,2=only" */="" 4="use" any="" host="" (unsafe)="" */="" miuint1="" fg_diffuse_depth;="" #secondary="" fg="" bounces="" */="" mitag="" state_func;="" allow="" user="" to="" init="" state="" */="" float="" fg_presamp_density;="" samples="" density="" for="" precomp.="" *="" finalgather="" points="" */="" float="" rast_shading_samples;="" shading="" samples="" per="" pixel="" */="" default:="" 1.0f="" */="" miuint1="" fb_virtual;="" fb="" mem="" management="" */="" 0="none" 1="mapped" 2="cached" */="" default:="" 1="" */="" micboolean="" spare3[3];="" not="" used="" */="" mitag="" string_options;="" arbitrary="" name-value="" options="" */="" int="" spare[9];="" not="" used="" */="" };="" />

A translator must provide: nothing.

A translator may provide: all fields.

trace
enables ray tracing to compute secondary rendering effects like reflections and refractions.
The default is miTRUE.
scanline
enables a scanline rendering algorithm to accelerate computation of first-hit intersections with primary visible objects. The value can be one of
miRENDER_FH_OFF
to disable scanline rendering,
miRENDER_FH_SCANLINE
to enable scanline rendering,
miRENDER_FH_OPENGL
to use OpenGL hardware of the system for accelerated scanline rendering,
miRENDER_FH_RAST
to utilize the rasterizer for optimized performance together with motion blur.
The default is miRENDER_FH_SCANLINE.
motion
enables computation of motion blur.
The default is miFALSE.
preview_mode
is currently not used.
reflection_depth
limits the ray tracing depth for reflection rays.
The default is 2.
refraction_depth
limits the ray tracing depth for refraction or transparency rays.
The default is 2.
trace_depth
limits the ray tracing depth for the sum of any reflection, refraction, and transparency rays.
The default is 4.
min_samples
specifies the minimum sample level in each direction in recursive oversampling mode. The actual number of samples is computed by 2level in each direction, and determines how many samples are at least taken. See the samples option for further explanation.
The default is -2 (at least 1 sample per 16 pixels).
Does not apply to rasterizer.
max_samples
specifies the maximum sample level in each direction in recursive oversampling mode. The actual number of samples is computed by 2level in each direction, and determines how many samples are at most taken. See the samples option for further explanation.
The default is 0 (at most 1 sample per 1 pixel).
Does not apply to rasterizer.
contrast
specifies the contrast limit above which more spatial samples are taken.
The default is 0.1 0.1 0.1 0.1.
Does not apply to rasterizer.
time_contrast
controls the number of temporal samples used for motion blur rendering. The value is approximately equal to the inverse of the number of the temporal samples. Because of blurring, this can usually be much higher than the spatial contrast.
The default is 0.2 0.2 0.2 0.2.
contour_contrast
specifies a function that computes contrasts in contour rendering mode.
The default is miNULLTAG.
contour_store
specifies a function that collects and stores sample information for use by the contour contrast function, in contour rendering mode.
The default is miNULLTAG.
caustic
specifies whether caustics should be rendered.
The default is miFALSE.
globillum
specifies whether global illumination should be rendered.
The default is miFALSE.
caustic_accuracy
specifies the number of photons to use when estimating radiance for caustics.
The default is 100.
caustic_radius
specifies the maximum distance in which photons used in the radiance estimate for caustics are located. If the radius is 0.0 then an estimate based on the scene extent will be used.
The default is 0.0.
globillum_accuracy
specifies the number of photons to use when estimating radiance for global illumination.
The default is 500.
globillum_radius
specifies the maximum distance in which photons used in the radiance estimate for global illumination are located. If the radius is 0.0 then an estimate based on the scene extent will be used.
The default is 0.0.
caustic_filter_const
is a constant used when filtering caustics radiance estimates.
The default is 1.1.
filter_size_x
specifies the width of the filter specified in the filter field.
The default is 1.0.
filter_size_y
specifies the height of the filter specified in the filter field.
The default is 1.0.
jitter
is the jitter interval. Jittering displaces samples to avoid sampling artifacts.
The default is 1.0.
shutter
is the shutter close time of the camera if motion blur is enabled. It may not be negative.
The default is 0.0.
grid_res Deprecated
controls the voxel grid resolution in X, Y, and Z directions, if acceleration is set to 'g' (grid). If all three are 0, mental ray uses a default computed from the scene.
The default is 0 0 0.
grid_max_size Deprecated
controls the maximum size of each grid voxel, if acceleration is set to 'g' (grid).
The default is 128.
grid_max_depth Deprecated
controls the maximum nesting depth of grids, if acceleration is set to 'g' (grid).
The default is 2.
def_min_samples
sets a global default value for per object min_samples option. An object may set its local min_samples value to achieve custom oversampling effects in the area of the image that it covers. See the related samples object setting for further explanation. Like the per object min/max samples parameters, the default value should stay within the global sampling range specified in the options with min_samples…max_samples to have an impact on oversampling. A value of -128 turns per object control off; and the global min_samples will be used as usual.
The default is -128.
def_max_samples
sets a global default value for max_samples option on objects. See the related def_min_samples for details. A value of 127 turns per object control off; and the global max_samples will be used as usual.
The default is 127.
space_max_size
is the maximum leaf size for BSP.
The default is 10.
This does not apply to BSP2.
space_max_depth
is the maximum tree depth for BSP.
The default is 40.
This does not apply to BSP2.
shutter_delay
is the shutter open time of the camera if motion blur is enabled. It allows starting the shutter interval late, which ranges from t = shutter_delay to shutter. This is useful for shifting the evaluation time to the center of the frame by setting shutter_delay and shutter to the same value, such as 0.5, and then doing bidirectional postprocessing motion blur.
The default is 0.0.
no_images Deprecated
is always 1. In previous versions it was the number of valid entries in the images_info array described below.
The default is 1.
images_info
is a database array which specifies the frame buffers. There are no_images entries in the array. Each entry has the type miFb_info, which is described below. Frame buffers may be accessed only in output shaders. 
typedef struct miFb_info {
        miImg_type      image_type;             /* image types */
        miUint4         write_image;            /* bits: 0=sample image */
                                                /*       1=write  image */
        miBoolean       interp_image            /* interpolate image? */
} miFb_info;
See the public header file shader.hfor a list of valid image types.
image_types
specifies the image types to be generated during rendering.
The default is miIMG_TYPE_RGBA.
write_image
specifies for each image whether it is sampled (if bit 0 is 1) and written to a file (if bit 1 is 1) after rendering completes. mental ray 2.1 combined both bits into a single boolean.
The default is 3.
interp_image
specifies for each image whether it is to be interpolated. This means that if fewer than one sample per pixel is taken, the holes are filled in.
The default is miTRUE, miFALSE, ....
finalgather_file
is a tag to a database string containing the filename of a file from which a finalgather point map should be loaded (if possible) or otherwise saved to. If this tag is a miNULLTAG then no finalgather map is loaded or saved.
The default is miNULLTAG.
space_shadow_separate
turns on a separate BSP tree for shadow objects in addition to the main BSP tree for traceable geometry. The trace and shadow flags are attributes of geometric objects. Objects that have both flags set will go into both BSP trees, which is less efficient.
The default is miFALSE.
finalgather_filter
specifies the size of the final gathering speckle removal filter. A value of 0 means off; values greater than 4 are not normally useful.
The default is 1.
rast_collect_rate
for the rasterizer specifies the number of samples per pixel dimension. If set to 0 an internal default will be used, which is 3 giving 9 samples per pixel. Note, in contrast to adaptive sampling settings, the number of samples is not given as power of 2.
The default is 0.
rast_shading_samples
for the rasterizer specifies the number of shading calls per pixel. If set to 0 the internal default will be used, which is 1.0.
The default is 0.
rast_motion_resample
for the rasterizer controls the number of samples in time.
The default is 0.
use_shadow_maps
if miTRUEenables shadowmaps to be used for the light sources which have shadowmaps specified. If set to 'o' shadowmaps are computed using OpenGL. mental ray allows setting bit 7 independently to only render shadowmaps to files, if applicable, but omit the main rendering stage (similar to -shadowmap only on the command line of standalone mental ray). This flag applies to all shadowmaps in the scene.
The default is 0 (off).
rendering_shadow_maps
is set to miTRUE by mental ray when shadowmaps are being rendered. This option is internal to RC and only used to optimize the rendering of shadowmaps.
The default is miFALSE.
recompute_shadow_maps
can be 'y' or 'n'. 'y' means that all shadowmaps are recomputed even if they could have been loaded from a file. 'n' means that shadowmaps are only computed if they could not be re-used or loaded from a file (shadowmaps are recomputed "intelligently" meaning that the shadowmap code tries to identify those light sources for which a new shadowmap needs to be recomputed. This recomputation currently only applies to light sources for which the position or direction of the emitted light - ie. the transformation matrix - changes in an animation).
shadow
(default 1) controls shadow casting. It is one of 0 (no shadows), 1 (normal shadows), 's' (shadow segments with separate volume shaders), and 'l' (shadow intersections sorted from the light source towards the illumination point).
caustic_filter
is the type of filter used: 'b' box filter, 'c' cone filter and 'g' gauss filter.
finalgather_rebuild
(default miFALSE) if set to miTRUE then final gathering is re-computed in every frame of an animation.
filter
(default 'b') is one of 'b' (box filter), 't' (triangle filter), 'g' (Gaussian filter), 'm' (Mitchell filter), or 'l' (Lanczos filter).
acceleration
(default 'b') is one of 'b' (space subdivision, BSP), 'l' (large-scene BSP), and 'g' (grid).
face
(default 'a') enables backface culling, one of 'f' (front-facing only), 'b' (back-facing only), and 'a' (both). During rendering, mental ray 3.x copies the face flag to the shader state to make it controllable by shaders.
field
is not used.
smethod
is not used.
render_space
(default 'c') is 'o' for object space (recommended) or 'c' for camera space (default).
pixel_preview
is set when pixel previewing should be used. The default is off.
task_preview
is set when task previewing should be used. The default is off.
visible_lights
is set if there are any area lights with the 'visible' flag. This option is internal to RC and used to optimize rendering.
shadow_map_motion
enables motion blurring of shadowmap shadows. The default is on.
task_size
(default 0) is the size of the image tasks to be rendered. If it is zero, a heuristic based on the image resolution will be used in RC in order to calculate an appropriate value. task_size can also be specified explicitly.
strips
specifies whether the approximated geometry is represented as triangle strips and fans. The default is off.
photonmap_file
is a string containing the filename of a file from which a photon map should be loaded (if possible) or otherwise saved to. If this tag is a miNULLTAG then no photon map is loaded or saved.
photonmap_rebuild
will, if true, enforce a recomputation of the photon map even if it could have been loaded from a file.
photon_reflection_depth
controls the trace depth of reflected photons. The default is 5.
photon_refraction_depth
controls the trace depth of refracted photons. The default is 5.
photon_trace_depth
controls the combined trace depth of reflected and refracted photons. The default is 5.
space_max_depth
is not used.
caustic_scale
is multiplied into the indirect illumination from caustics. Values greater than 1 increase the brightness of the effect. If just this option is changed, it is correct to re-render scene with photonmap_rebuild set to false.
globillum_scale
is multiplied into the irradiance obtained from global illumination photonmap lookup. Values greater than 1 increase the brightness of the effect. If just this option is changed, it is correct to re-render scene with photonmap_rebuild set to false.
finalgather_scale
is multiplied into the indirect illumination obtained from final gathering. This allows fast artistic tuning of indirect illumination. If just this option is changed, it is correct to re-render scene with finalgather_rebuild set to false, saving the finalgather preprocessing step.
finalgather_sec_scale
is multiplied into the indirect illumination obtained from secondary bounces of final gathering. This allows fast artistic tuning of indirect illumination. If just this option is changed, it is correct to re-render scene with finalgather_rebuild set to false, saving the finalgather preprocessing step.
photonvol_scale
is multiplied into the indirect illumination obtained from volume photons. Values less than 1 decrease the contribution of the effect.
spectrum_blueprint
input_cprof
is a tag associated with a color profile describing the color space for input images like textures. If this value is not set, then no color space transformation is performed but input textures are assumed to be given in the render color space.
white_cprof
is a tag associated with a color profile used to perform all white point adaptions when transforming from the rendering color space to the output color profile. If this value is not set, then any white point adaptions are performed in mental rays internal color space.
render_cprof
is a tag associated with a color profile describing the rendering color space. If this value is not set, then rendering is performed in a device dependent color space which is identical with the output color space. If the value is set to a valid color profile, then rendering is performed in this color space. The results in the color frame buffer are stored in mental rays internal color space.
fb_dir
is a string containing the directory for frame buffer files on disk. If this is a null tag then defaults are taken from environment variables.
no_lens
if miTRUEdisables all lens shaders. The default is miFALSE.
no_volume
if miTRUEdisables all volume shaders. The default is miFALSE.
no_geometry
if miTRUEdisables all geometry shaders. The default is miFALSE.
no_displace
if miTRUEdisables all displacement shaders. The default is miFALSE.
no_output
is a bitmap. Bit zero, it set, disables all output shaders. Bit one, if set, disables writing of output image files. The default is zero for both bits.
no_merge
if miTRUEdisables all edge merging and adjacency detection. The default is miFALSE.
caustic_flag
is the default caustic flag for objects. The default value is 3, making all objects caustic generators and caustic receivers.
diagnostic_mode
controls alternate rendering modes for diagnostic purposes. It is a bitmap. The only currently supported bit is miSCENE_DIAG_SAMPLES which, when set, turns on sample view mode. The default value is zero for all bits.
photonvol_accuracy
specifies the number of photons to use when estimating radiance inside participating media.
photonvol_radius
specifies the maximum distance in which photons used in the radiance estimate for participating media are located. If the radius is 0.0 then an estimate based on the scene extent will be used.
cut_windows
2.1 enables rendering every image as n × n cut windows if set greater than zero.
cut_expand
2.1 increases the cut window frustum by a factor all around the frustum if greater than zero, to catch invisible outside geometry that becomes visible because it is displaced into the frustum. The default is 0.1. It has an effect only if cut windows are enabled.
globillum_flag
is the default globillum flag for objects. The default value is 3, making all objects globillum generators and receivers.
samplelock
(default miTRUE) uses the same sampling sequences for every frame, causing sampling noise to remain unchanged in unchanged parts of the scene. If set to miFALSE, the sequences are initialized with the frame number to cause moving noise.
autovolume
(default miFALSE enables automatic volume tracking by mental ray. This allows managing overlapping volumes and a camera that is inside one or more volumes, to always call the correct volume shaders.
finalgather_view
(default miFALSE) switches the final gather radius parameters from world space to projected raster space.
no_hair
if set, disables hair rendering.
n_motion_vectors
3.1 specifies the number of curve segments into which motion transformations should be subdivided to create a smooth curved motion path. This must be a number in the range 1..15. The default is 1. The scene language equivalent is motion steps.
no_pass
3.1 disables sample pass rendering. All pass statements in the camera will be ignored.
photon_autovolume
enables autovolume mode for photons. Autovolume mode keeps track of the volumes or list of volumes that a photon is in, depending on volume shaders and their mixing properties on materials.
no_predisplace
turns off displacement presampling, which normally attempts to improve bounding box quality by checking a number of displaced points for extreme values.
fg_reflection_depth
is a trace depth for reflected finalgather rays. This implements multi-generation final gathering in a way similar to reflection_depth for regular rays.
fg_refraction_depth
is a trace depth for refracted finalgather rays.
fg_diffuse_depth
is a trace depth for secondary diffuse bounces.
fg_trace_depth
is a total trace depth for reflected and refracted finalgather rays.
fg_falloff_start
specifies the starting distance for finalgather falloff.
fg_falloff_stop
specifies the stopping distance for finalgather rays. The total length of finalgather rays cannot exceed the stop distance, and is attenuated with a linear falloff curve between the start and stop distances. If both are set to 0.0, no falloff takes place.
approx
overrides all base surface approximations in objects, both free-form surfaces and polygonal, if the approximation style is not miAPPROX_STYLE_NONE. This style is the default, and all other fields are 0. Use the miAPPROX_DEFAULT macro to activate this approximation. See the miApprox data structure description above.
approx_displace
is the same thing for displacement approximations.
finalgather
enables final gathering. The default is off.
finalgather_rays
is the number of rays shot in each final gather. The default is 1000.
finalgather_maxradius
is the maximum radius in which a final gather result can be used for interpolation or extrapolation. If this radius is 0.0 then an estimate based on the scene extent will be used.
finalgather_minradius
indicates that a final gather result must be used for interpolation or extrapolation if it is within this distance. If this radius is 0.0, it will be set to 10% of finalgather_maxradius.
diag_photon_density
scales the diagnostic photon density mode by defining the density where the diagnostic color range peaks.
diag_grid_size
defines the grid width of the diagnostic grid mode.
desaturate
used to be set with mi_img_mode2.1. If enabled, colors exceeding the 0..1 range will not be clipped per component, but the whole color is faded to white. This has an effect only when storing colors in 8-bit or 16-bit color frame buffers.
dither
was also handled by mi_img_mode2.1. It enables LSB dithering when storing colors in 8-bit or 16-bit color frame buffers, to avoid color banding.
nopremult
was also handled by mi_img_mode2.1. It turns off premultiplication when storing colors in the frame buffer.
colorclip
was also handled by mi_img_mode2.1. Sets the color clipping when storing colors in 8-bit or 16-bit color frame buffers to miIMG_COLORCLIP_RGB (preserve RGB and adjust alpha), miIMG_COLORCLIP_ALPHA (preserve alpha and adjust RGB), or miIMG_COLORCLIP_RAW (disable color clipping).
gamma
was also handled by mi_img_mode2.1. It applies gamma correction if gamma is less than or greater than 1.0, when storing colors in 8-bit or 16-bit color frame buffers.
inh_funcdecl
contains the inheritance function.
luminance_weight
(default 0.33, 0.33, 0.33) controls the weights that mi_luminance will assign to R, G, and B, respectively, to compute the luminance value.
split_obj_no_triangs
is not used.
split_obj_no_faces
is not used.
inh_is_traversal
3.1 (mental ray 3.1.2), if true, switches the inheritance function described by inh_funcdecl to a traversal shader. It works the same way but gets a different argument set that is more powerful. New projects should rely on traversal functions instead of inheritance functions.
hardware Deprecated
is used for internal purposes only. It controls when mental ray will use hardware shaders: never, if available, or always (even if the shading result can only be approximated).
hardware_diagnostic Deprecated
is reserved.
shadowmap_flags
is a bitmap of bits 0 (shadowmap merge), and bit 3 (shadowmap only). The other bits must be cleared.
maxdisplace
if set to a value other than zero, overrides the maxdisplace values when approximating a displaced object. This is useful if an old scene without object maxdisplace values must be rendered without truncating all displacement to zero.
shadowmap_bias
supplies a shadowmap bias value to all shadowmaps attached to light sources. This is a simple way to switch all of mental ray to biased shadowmaps without modifying all lights.
hwshader Deprecated
is a bitmap of hardware allowed shading modes that mental ray will try in turn until one succeeds:
photonmap_only
if true, means that only the photon maps and not the camera images are rendered. The default is false.
lightmap
flag controls rendering of lightmaps. The settings are 0 (off), 1 (on), and 2 (only). By default, lightmaps are enabled. If this option is set to 2 only the lightmaps and not the camera images are rendered.
state_func
is the tag of the optional state shader that is called at the beginning and end of the lifetime of a state or a primary ray or similar shader call.
fg_presamp_density
controls the density of initial finalgather points. It increases (decreases if fg_presamp_density < 1) the number of finalgather points computed in the initial stage approximately fg_presamp_density times.
rapid_shading_samples
sets the number of shading samples per pixel for the rasterizer (default is 1.0). Only has an effect for scanline = miRENDER_FH_RAST.
fb_virtual
controls whether frame buffers are maintained in memory (0), or memory-mapped to disk in single potentially large chunks (1), or cached to disk in pieces (2). The default is 1, which allows an arbitrary number of frame buffers or arbitrary resolution without filling up physical memory on 64bit systems. On 32bit systems with limited memory address space mode 2 may be more appropriate. For certain applications such as fast preview rendering it may be desirable to keep the framebuffer in main memory by setting this flag to 0.

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