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RTRACE.LST
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1992-07-27
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RTRACE(1G)
NAME
rtrace - ray tracing program
SYNOPSIS
rtrace [options] scene image [>log]
AUTHOR
Antonio Costa, INESC-Norte, 1989 1992
DESCRIPTION
_r_t_r_a_c_e command performs ray tracing from a _S_F_F text file
which must describe a scene with objects, lights, surface
definitions, textures, etc. This scene file must be in the
appropriate format, as described bellow.
Basically, ray tracing is an algorithm for the creation of
realistic images from the geometry and attributes of
objects, lights, etc. This ray tracer supports several
types of objects (sphere, box, bicubic patch, cone,
cylinder, polygon, triangle and text), CSG and list opera-
tions, different light types, reasonable surface defini-
tions, lots of textures, several anti-aliasing schemes,
depth of field, stereoscopic image creation and so on...
OPTIONS
[w_i_m_a_g_e-_w_i_d_t_h] [h_i_m_a_g_e-_h_e_i_g_h_t]
The parameters _i_m_a_g_e-_w_i_d_t_h and _i_m_a_g_e-_h_e_i_g_h_t define the image
size. Defaults are 256x256.
[A_a_l_i_a_s_i_n_g-_t_h_r_e_s_h_o_l_d]
[S_s_h_a_d_i_n_g-_t_h_r_e_s_h_o_l_d]
[T_a_m_b_i_e_n_t-_t_h_r_e_s_h_o_l_d]
The parameters _a_l_i_a_s_i_n_g-_t_h_r_e_s_h_o_l_d (pixel supersampling),
_s_h_a_d_i_n_g-_t_h_r_e_s_h_o_l_d (shading rays propagation) and _a_m_b_i_e_n_t-
_t_h_r_e_s_h_o_l_d (ambient rays distribution caching) control the
image quality (0-best, 1-poor). Defaults are 0.05, 0.01 and
0 (no ambient threshold). Good ranges are 0.1-0.03, 0.01-
0.001 and 0.01-0.00001, respectively.
[a_a_n_t_i_a_l_i_a_s_i_n_g-_m_o_d_e]
The parameter _a_n_t_i_a_l_i_a_s_i_n_g-_m_o_d_e chooses adaptive supersam-
pling antialiasing (0-default), semi-adaptive supersampling
antialiasing (1) or normal supersampling antialiasing (2-
should be used with nonzero focal apertures).
[B_m_a_s_k_f_i_l_e]
The parameter _m_a_s_k_f_i_l_e creates a file with a background
mask, suitable for mixing images (it is like an alpha chan-
nel).
[c_c_l_u_s_t_e_r-_s_i_z_e]
The parameter _c_l_u_s_t_e_r-_s_i_z_e controls the enclosing of objects
(number of grouped objects per cluster) in the object
hierarchy. Use a low value for sparse scenes, a high value
for dense scenes (4-default).
[d_a_m_b_i_e_n_t-_l_e_v_e_l_s]
The parameter _a_m_b_i_e_n_t-_l_e_v_e_l_s defines the number of shading
levels (shading tree depth) in which ambient lighting
calculations will be done through ray distribution (0-
default, ie, no ray distribution). Use low values!
[D_a_m_b_i_e_n_t-_s_a_m_p_l_e_s]
The parameter _a_m_b_i_e_n_t-_s_a_m_p_l_e_s defines the maximum number of
distributed rays to be used in ambient lighting calculations
(16-default). Again, use with care.
[i_i_n_t_e_r_s_e_c_t-_m_o_d_e]
The parameter _i_n_t_e_r_s_e_c_t-_m_o_d_e chooses, in adaptive supersam-
pling antialiasing, between testing all scene objects (1) or
only the objects found at the pixel corners and inside (0-
default; this greatly reduces CPU time, but with very small
objects, it sometimes fails).
[I_i_n_t_e_r_s_e_c_t-_a_d_j_u_s_t-_m_o_d_e]
The parameter _i_n_t_e_r_s_e_c_t-_a_d_j_u_s_t-_m_o_d_e avoids some problems
with invalid self-intersections (1) (0-default). Scenes
with text objects should be traced with this parameter equal
to 1.
[j_j_i_t_t_e_r_i_n_g-_m_o_d_e]
The parameter _j_i_t_t_e_r_i_n_g-_m_o_d_e chooses jittered sampling (1)
or not (0-default). Sometimes, activating it produces better
images from scenes with small tricky details.
[l_l_i_g_h_t_i_n_g-_m_o_d_e]
The parameter _l_i_g_h_t-_m_o_d_e controls the generation of shadow
rays through non-opaque objects: 0-none (default), 1-
partial, 2-full. If a scene has translucent objects, to
obtain realism one should use 1 or 2 (better).
[m_s_h_a_d_i_n_g-_m_o_d_e]
The parameter _s_h_a_d_i_n_g-_m_o_d_e chooses between shading models:
0-normal phong, 1-strauss (default but slower) (note: this
model was developed by Paul Strauss of SGI).
[n_n_o_r_m_a_l-_m_o_d_e]
The parameter _n_o_r_m_a_l-_m_o_d_e controls the correction of surface
normals, so that it points against the incident ray: 0-
always (default), 1-only inside objects. With "correct"
objects, it is good to use 1.
[z_n_o_r_m_a_l-_c_h_e_c_k-_m_o_d_e]
The parameter _n_o_r_m_a_l-_c_h_e_c_k-_m_o_d_e controls the correction of
surface normals when textures that modify the normal are
used, as they may sometimes create strange surface effects.
This tends to happen if the scale of the normal perturbation
is big. 0-no correction (default), 1-correction.
[R_r_a_w_f_i_l_e]
The parameter _r_a_w_f_i_l_e creates a raw image file, without any
antialiasing (all defects show up!).
[p_s_a_m_p_l_i_n_g-_l_e_v_e_l_s]
The parameter _s_a_m_p_l_i_n_g-_l_e_v_e_l_s controls the amount of sam-
pling levels inside pixels: 0-none ... 3-maximum (default).
A reasonable value is 2 for high resolutions, but for small
ones 3 gives better (and slower) results.
[s_s_h_a_d_i_n_g-_l_e_v_e_l_s]
The parameter _s_h_a_d_i_n_g-_l_e_v_e_l_s establishes a maximum shading
tree depth (default is 8). When a scene has
transparent/reflective objects, it may be important to lower
this parameter, or else the tracing never stops. In the
other cases, there should be no problem allowing it to be
big.
[t_t_e_x_t_u_r_e-_m_o_d_e]
The parameter _t_e_x_t_u_r_e-_m_o_d_e allows the definition of
texture(s) for the objects: 0-no textures (default), 1-with
textures defined inside objects field, 2-with textures
defined after objects field. As textures may consume much
CPU time, they should be activated only for final images.
[v_v_i_e_w-_m_o_d_e]
The parameter _v_i_e_w-_m_o_d_e chooses the view mode: 0-normal
(default), 1-left eye, 2-right eye.
[P_f_o_c_a_l-_a_p_e_r_t_u_r_e]
The parameter _f_o_c_a_l-_a_p_e_r_t_u_r_e defines the focal aperture of
the camera (default 0.0, ie, pinhole camera). If different
than zero, there is depth of field, and so adaptive super-
sampling antialiasing will not work well.
[F_f_o_c_a_l-_d_i_s_t_a_n_c_e]
The parameter _f_o_c_a_l-_d_i_s_t_a_n_c_e defines the focal distance of
the camera (default is the distance from the eye point to
the look point).
[E_s_t_e_r_e_o-_s_e_p_a_r_a_t_i_o_n]
The parameter _s_t_e_r_e_o-_s_e_p_a_r_a_t_i_o_n controls the separation
between the left and the right eye. If negative, it
represents a percentage of the gaze distance.
[O_o_u_t_p_u_t-_f_o_r_m_a_t]
The parameter _o_u_t_p_u_t-_f_o_r_m_a_t chooses between the PIC format
(0-default) or the PPM format (1).
[V_v_e_r_b_o_s_e-_m_o_d_e]
The parameter _v_e_r_b_o_s_e-_m_o_d_e supresses any messages (0) or
shows listing of parameters (1), previous plus statistics
(2-default) or previous plus a line by line echo of the
tracing (3-default on DOS and trans