RT(1)

selects auto-sizing, and gives the view azimuth in degrees. Used with -e and conflicts with -M .

is sometimes useful for debugging. A single ray is fired at the specified linear pixel index or X and Y pixel coordinates. This is best when accompanied by debugging options. Because getopt(3) only allows one option parameter, coordinate pairs must be enclosed in double quotes. This option must follow any viewing parameters.

is for specifying commands for rt to run prior to ray tracing. The "script_command" can be a single command or a semi-colon separated list of commands. The commands available are the same commands that may appear in a -M command script.

selects auto-sizing, and gives the view elevation in degrees. Used with -a and conflicts with -M .

sets the grid cell width, in millimeters. Ordinarily, the cell width is computed by dividing the view size by the number of pixels of width, so this option need not be used. To obtain exactly 1 inch ray spacing, specify -g25.4 . If the grid cell width is specified and the grid cell height (which would be set using -G) is not specified, the grid cell height defaults to be the same as the width.

enables an exponential shading of the void between the eye and the first hit location. This allows a cheap simulation of atmospheric haze with lower performance impact than explicit modeling of the air volume. The haze is computed using the form:

enables incremental mode processing. (First, a single ray is fired. Then, the screen is subdivided into four parts by evenly subdividing in the vertical and horizontal directions. The previously fired ray was the lower left corner; three more rays are fired. This process recurses until full resolution has been reached. Assumes square image. Also assumes fast path between CPU and display hardware.)

enables processing of just a sub-rectangle, located within the rectangle (0,0) (width-1,height-1), and whose screen coordinates (lower left and upper right corners) are provided in the argument. Ray-tracing will be limited to just those pixels within the sub-rectangle, and only those pixels will be transmitted to the framebuffer. The corner pixels (xmin,ymin) and (xmax,ymax) are included in the sub-rectangle. This option exists primarily for mged(1) to allow sweeping out a rectangular portion of the view for ray-tracing.

enables the use of a cutting plane. The xdir, ydir, zdir, and dist define a plane (equivalent to a halfspace primitive with the same parameters). The vector (xdir, ydir, zdir) is normal to the plane and points away from the space to be subtracted. The dist parameter specifies the distance from the origin to the plane in the normal direction. The resulting image approximates subtracting the halfspace from the objects being raytraced. The x,y,z,nx,ny,nz specifies the same plane using a point and a normal rather than the halfspace style specifier. The x,y,z form is shorthand for a point-normal plane whose point and normal both use the supplied vector, with the normal unitized internally. Note that this is not exactly the same as actually subtracting the halfspace, but it is faster. If explicit lights are used, objects that are cut away by the cutting plane will still cast shadows.

selects lighting model. Default is 0. Model 0 is a full lighting model with the ability to implement Phong shading, transparent and reflective objects, shadow penumbras, texture maps, etc. In addition to ambient light, a small amount of light is supplied from eye position. All objects in the active model space with a material property string of "light" represent additional light sources (up to 16 are presently permitted), and shadow computations will be initiated automatically. (This mechanism is subject to further change.) Model 1 is a diffuse-lighting model only, and is intended for debugging. Model 2 displays the surface normals as colors, and is useful for examining curvature and surface orientation. Model 3 is a three-light brighter lighting model. Model 4 is a curvature debugging display, showing the inverse radius of curvature. Model 5 is a curvature debugging display, showing the principal direction vector. Model 6 is for debugging the UV parameterization used for surface texturing. It is exactly the same as applying the texture 'testmap' to every region. The U parameter is displayed in the red channel and the V parameter is displayed in the blue channel. Model 7 is for using photon mapping to simulate global illumination and caustics in a given scene. Model 8 is a heat-graph diagnostic mode that records the high-resolution current-thread CPU time needed by the rendering worker to render each fully shaded pixel and maps those timings to a grayscale image; brighter pixels took longer to render. If a current-thread CPU timer is not available, rt falls back to wall-clock timing. Timings include shader work such as light visibility and shadow rays, and the grayscale image is normalized for comparative display rather than absolute timing. Heat-graph output is written through the same output destinations as normal rt rendering, including -o image files and -F framebuffers. Options to photon mapping are passed through the -l parameter in the following format:

defines the height of the image as a number of scanlines.

specifies the name of a file to store your output data file. For example, if you specify your output as image.pix, it will write out an image file in the pix(5) file format. If you specify an image.png file, it will write out an image file in the PNG file format. The pix-fb(1) and png-fb(1) utilities can be used to display ".pix" and ".png" files respectively.

sets the perspective, in degrees, with 0 < = # < 180

requests that overlapping regions be reported (on by default); opposite of -R .

specifies the number of rays to fire in the X and Y directions on a square grid. The default size is 512 (i.e., 512 x 512).

causes reversal of the order of grid traversal (default is not to do that)

specifies units, with "model" being used for the units of the local model

sets the output verbosity level for rt. You can use -v 0 for no/minimal output or add -v repeatedly up through four levels (e.g., -vvvv) to see all available output. Default is all available output. The -v option will also take a specific hexadecimal value to turn on specific message categories (e.g., -v 0xFF010030) of output.

defines the width of each scanline in pixels.

sets the librt(3) debug flags to the given hexadecimal bit vector. See raytrace.h for the bit definitions. (Notice that -! # sets the libbu(3) debug flags to the given hexadecimal bit vector. See bu.h for the bit definitions.)

enables (-z1) or disables (-z0) OpenCL accelerated raytracing. OpenCL must be enabled at compilation time for this option to have any effect.

specifies a material density definitions file, used by analysis-oriented views (such as rtweight(1)) to map region material codes to densities.

sets the number of entries used from the random-number half-table. The value must be greater than 0 and no larger than the compiled-in maximum. This is primarily of interest when tuning reproducibility of dithering and sampling.

reads the list of objects (treetops) to raytrace from the named text file, one object name per line, instead of (or in addition to) naming them on the command line.

sets the ambient light intensity, as a fraction of the total light in the scene in the range of 0.0 to 1.0 .

turns on the "benchmark" flag. This causes all intentional random effects such as ray dither, color dither, etc., to be turned off to allow benchmark timing comparison and benchmark result comparison.

sets the background color to the RGB value //#, where each # is in the range of 0 to 255 or 0.0 to 1.0. All non-background colors will be dithered away from this value.

This is the "desired frame" flag, specifying the frame number to start with. Used with animation scripts; specify the desired ending (kill-after) frame with -K # .

sets the distance from the eye point to the center of the model RPP; default is the square root of 2. Only useful with auto-sizing, and conflicts with -M .

indicates that the output should be sent to the indicated framebuffer. For remote framebuffer access, this may be a TCP-style specification (for example, host:port or port) or an IPC address using the form ipc:*addr. See *brlcad(1) for more details on framebuffer naming.

sets the grid cell height, in millimeters. If the grid cell height is specified and the grid cell width (which would be set using -g) is not specified, the grid cell width defaults to be the same as the height.

This is the "hypersample" flag, specifying number of extra rays to fire for each pixel to obtain more accurate results without needing to store the extra pixels. Automatically invokes -J 1. The final colors of all rays are averaged together. Better results can be obtained by simply increasing the resolution, and decimating the results with a filter such as pixhalve(1).

This is the "jitter" flag, which is a bit vector. If one (-J 1), it randomizes the point from which each ray is fired by +/- one half of the pixel size. Useful if doing your own post-filtering for antialiasing, or to eliminate systematic errors. This has been useful in obtaining more accurate results in a volume-calculating raytrace as well. If two (-J 2), it shifts the origin of the output frame once for each frame. The shift is along a circular path in the plane of the frame, with a period of ten seconds, and a radius of +/- 1/4 pixel width. If three (-J 3), it performs both operations.

sets the final (kill-after) frame number. Used with animation scripts in conjunction with -D # .

causes reading of animation (model2view) matrix or animation script from standard input. Conflicts with -a and -e options.

sets the NMG_debug flags to the given hexadecimalbit vector. See h/nmg.h for the bit definitions.

specifies the name of a file in which to store a double-precision floating-point version of the image in dpix(5) format. dpix-pix(1) can be used to later convert the file to pix(5) format output.

Specify the maximum number of processor cores to be used on multicore systems. The default is the maximum number of cores available for the machine. Negative numbers indicate using all except for the count specified.

selects pixel ray for query with debugging. The option is used to specify a single pixel for which the debug flags should be turned on. The computation of all other pixels will be performed without debugging. This is similar to the -b option, except that it does not limit rendering to the single ray. The entire image is computed. This option is useful in debugging problems which arise from specific computation sequences (such as the order of random numbers previously drawn).

requests that overlapping regions not be reported; opposite of -r .

turns on stereo viewing. The left-eye image is drawn in red, and the right-eye image is drawn in blue.

sets the calculation tolerances used by librt(3). If only one number is given, it specifies the distance tolerance. Any two entities closer than this distance are considered to be the same. The default distance tolerance is 0.0005mm. If the second number is given, it specifies the value of the dot product below which two lines are to be considered perpendicular. This number should be near zero, but in any case should be less than 1. The default perpendicular tolerance is 1e-6. If both calculation tolerances are provided, they shall be separated by either a slash ("/") or a comma (","), with no white space between them. For example, the default tolerances would be specified as -T0.0005/1e-6 on the command line.

sets the Boolean variable use_air to the given value. The default is 0, which ignores regions that have non-zero aircode values.

sets the view aspect. This is the ratio of width over height and can be specified as either a fraction or a colon-separated ratio. For example, the NTSC aspect ratio can be specified by either -V1.33 or -V4:3 .

specifies rendering on a white background. this option sets the image background color to pure white. This is equivalent to setting -c "set background=1.0/1.0/1.0".

sets the liboptical program debugging flags to the given hexadecimal bit vector. See raytrace.h for the meaning of these bits.

turns on the libbu(3) library debugging flags. See bu.h for the meaning of these bits. In particular, specifying -!1 will cause bu_bomb() to dump core, rather than logging the error and exiting. This is useful with dbx(1) or gdb(1) for debugging. (Notice that -x # sets the librt(3) debug flags to the given hexadecimal bit vector. See raytrace.h for the bit definitions.)

specifies (with the argument "t") that output is text rather than binary (the default is binary). No other argument value is accepted.

selects the space-partitioning algorithm. This option is temporarily disabled and currently causes rt to exit with an error if used.

prints a usage summary listing all options and exits.