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.\" RCSid "$Id" |
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.\" RCSid "$Id$" |
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.TH RPICT 1 2/26/99 RADIANCE |
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.SH NAME |
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rpict - generate a RADIANCE picture |
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to the letter 'c'. |
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This view is like a standard perspective vertically, but projected |
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on a cylinder horizontally (like a soupcan's-eye view). |
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Two fisheye views are provided as well; 'h' yields a hemispherical fisheye |
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view and 'a' results in angular fisheye distortion. |
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Three fisheye views are provided as well; 'h' yields a hemispherical fisheye |
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view, 'a' results in angular fisheye distortion, and 's' |
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results in a planisphere (stereographic) projection. |
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A hemispherical fisheye is a projection of the hemisphere onto a circle. |
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The maximum view angle for this type is 180 degrees. |
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An angular fisheye view is defined such that distance from the center of |
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the image is proportional to the angle from the central view direction. |
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An angular fisheye can display a full 360 degrees. |
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A planisphere fisheye view maintains angular relationships between lines, |
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and is commonly used for sun path analysis. |
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This is more commonly known as a |
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"stereographic projection," but we avoid the term here so as not to |
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confuse it with a stereoscopic pair. |
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A planisphere fisheye can display up to (but not including) 360 degrees, |
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although distortion becomes extreme as this limit is approached. |
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Note that there is no space between the view type |
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option and its single letter argument. |
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.TP |
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.BI -vd " xd yd zd" |
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Set the view direction vector to |
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.I "xd yd zd". |
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The length of this vector indicates the focal distance as needed by the |
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.I \-pd |
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option, described below. |
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.TP |
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.BI -vu " xd yd zd" |
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Set the view up vector (vertical direction) to |
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rendering an image a piece at a time. |
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A value of 1 means that the rendered image starts just to the right of |
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the normal view. |
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A value of -1 would be to the left. |
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A value of \-1 would be to the left. |
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Larger or fractional values are permitted as well. |
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.TP |
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.BI -vl \ val |
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.BI -vf \ file |
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Get view parameters from |
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.I file, |
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which may be a picture or a file created by rview (with the "view" command). |
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which may be a picture or a file created by rvu (with the "view" command). |
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.TP |
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.BI -x \ res |
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Set the maximum x resolution to |
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.I \-pm |
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option, to avoid the ghosting effect of too few time samples. |
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.TP |
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.BI -pd \ dia |
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Set the pixel depth-of-field aperture to a diameter of |
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.I dia |
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(in world coordinates). |
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This will be used in conjunction with the view focal distance, indicated |
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by the length of the view direction vector given in the |
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.I \-vd |
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option. |
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It is not advisable to use this option in combination with the |
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.I pdfblur(1) |
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program, since one takes the place of the other. |
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However, it may improve results with |
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.I pdfblur |
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to use a very small fraction with the |
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.I \-pd |
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option, to avoid the ghosting effect of too few samples. |
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.TP |
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.BI -dj \ frac |
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Set the direct jittering to |
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.I frac. |
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.I frac |
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is too large. |
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It is usually wise to turn off image sampling when using |
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direct jitter by setting -ps to 1. |
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direct jitter by setting \-ps to 1. |
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.TP |
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.BI -ds \ frac |
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Set the direct sampling ratio to |
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.I \-i |
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option so that light sources do not appear in the output. |
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.TP |
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.BI -sj \ frac |
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Set the specular sampling jitter to |
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.I frac. |
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This is the degree to which the highlights are sampled |
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for rough specular materials. |
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A value of one means that all highlights will be fully sampled |
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using distributed ray tracing. |
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.BI -ss \ samp |
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Set the specular sampling to |
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.I samp. |
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For values less than 1, this is the degree to which the highlights |
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are sampled for rough specular materials. |
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A value greater than one causes multiple ray samples to be sent |
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to reduce noise at a commmesurate cost. |
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A value of zero means that no jittering will take place, and all |
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reflections will appear sharp even when they should be diffuse. |
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This may be desirable when used in combination with image sampling |
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.TP |
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.BR -bv |
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Boolean switch for back face visibility. |
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With this switch off, back faces of opaque objects will be invisible |
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to all rays. |
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With this switch off, back faces of all objects will be invisible |
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to view rays. |
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This is dangerous unless the model was constructed such that |
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all surface normals on opaque objects face outward. |
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all surface normals face outward. |
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Although turning off back face visibility does not save much |
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computation time under most circumstances, it may be useful as a |
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tool for scene debugging, or for seeing through one-sided walls from |
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the outside. |
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This option has no effect on transparent or translucent materials. |
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.TP |
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.BI -av " red grn blu" |
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Set the ambient value to a radiance of |
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.BI -ab \ N |
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Set the number of ambient bounces to |
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.I N. |
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This is the maximum number of diffuse bounces |
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computed by the indirect calculation. |
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A value of zero implies no indirect calculation. |
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This is the maximum number of diffuse bounces computed by the indirect |
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calculation. A value of zero implies no indirect calculation. |
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.IP |
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This value defaults to 1 in photon mapping mode (see |
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.I -ap |
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below), implying that global photon irradiance is always computed via |
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.I one |
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ambient bounce; this behaviour applies to any positive number of ambient |
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bounces, regardless of the actual value specified. A negative value enables |
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a preview mode that directly visualises the irradiance from the global |
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photon map without any ambient bounces. |
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.TP |
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.BI -ar \ res |
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Set the ambient resolution to |
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.I Getinfo(1) |
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may be used to print out this information. |
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.TP |
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.BI -ae \ mat |
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.BI -ae \ mod |
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Append |
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.I mat |
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.I mod |
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to the ambient exclude list, |
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so that it will not be considered during the indirect calculation. |
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This is a hack for speeding the indirect computation by |
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ignoring certain objects. |
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Any object having |
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.I mat |
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.I mod |
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as its modifier will get the default ambient |
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level rather than a calculated value. |
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Any number of excluded materials may be given, but each |
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Any number of excluded modifiers may be given, but each |
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must appear in a separate option. |
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.TP |
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.BI -ai \ mat |
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.BI -ai \ mod |
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Add |
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.I mat |
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.I mod |
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to the ambient include list, |
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so that it will be considered during the indirect calculation. |
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The program can use either an include list or an exclude |
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.BI -aE \ file |
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Same as |
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.I \-ae, |
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except read materials to be excluded from |
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except read modifiers to be excluded from |
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.I file. |
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The RAYPATH environment variable determines which directories are |
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searched for this file. |
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The material names are separated by white space in the file. |
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The modifier names are separated by white space in the file. |
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.TP |
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.BI -aI \ file |
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Same as |
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.I \-ai, |
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except read materials to be included from |
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except read modifiers to be included from |
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.I file. |
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.TP |
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.BI -ap " file [bwidth1 [bwidth2]]" |
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Enable photon mapping mode. Loads a photon map generated with |
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.I mkpmap(1) |
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from |
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.I file, |
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and evaluates the indirect irradiance depending on the photon type |
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(automagically detected) using density estimates with a bandwidth of |
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.I bwidth1 |
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photons, or the default bandwidth if none is specified (a warning will be |
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issued in this case). |
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.IP |
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Global photon irradiance is evaluated as part of the ambient calculation (see |
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.I \-ab |
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above), caustic photon irradiance is evaluated at primary rays, and |
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indirect inscattering in |
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.I mist |
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is accounted for by volume photons. Contribution photons are treated as |
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global photons by |
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.I rpict. |
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.IP |
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Additionally specifying |
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.I bwidth2 |
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enables bias compensation for the density estimates with a |
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minimum and maximum bandwidth of |
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.I bwidth1 |
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and |
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.I bwidth2, |
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respectively. |
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.IP |
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Global photon irradiance may be optionally precomputed by |
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.I mkpmap(1), |
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in which case the bandwidth, if specified, is ignored, as the nearest photon |
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is invariably looked up. |
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.IP |
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Using direct photons replaces the direct calculation with density estimates |
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for debugging and validation of photon emission. |
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.TP |
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.BI -am " frac" |
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Maximum search radius for photon map lookups. Without this option, an |
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initial maximum search radius is estimated for each photon map from the |
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average photon distance to the distribution's centre of gravity. It is then |
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adapted to the photon density in subsequent lookups. This option imposes a |
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global fixed maximum search radius for |
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.I all |
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photon maps, thus defeating the automatic adaptation. It is useful when |
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multiple warnings about short photon lookups are issued. Note that this |
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option does not conflict with the bandwidth specified with the |
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.I \-ap |
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option; the number of photons found will not exceed the latter, but may be |
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lower if the maximum search radius contains fewer photons, thus resulting in |
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short lookups. Setting this radius too large, on the other hand, may |
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degrade performance. |
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.TP |
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.BI -ac " pagesize" |
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Set the photon cache page size when using out-of-core photon mapping. The |
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photon cache reduces disk I/O incurred by on-demand loading (paging) of |
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photons, and thus increases performance. This |
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is expressed as a (float) multiple of the density estimate bandwidth |
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specified with |
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.I \-ap |
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under the assumption that photon lookups are local to a cache page. Cache |
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performance is sensitive to this parameter: larger pagesizes will reduce the |
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paging frequency at the expense of higher latency when paging does occur. |
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Sensible values are in the range 4 (default) to 16. |
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.TP |
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.BI -aC " cachesize" |
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Set the total number of photons cached when using out-of-core photon |
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mapping, taking into account the pagesize specified by |
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.I \-ac. |
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Note that this is approximate as the number of cache pages is rounded to |
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the nearest prime. This allows adapting the cache to the available physical |
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memory. In conjunction with the |
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.I \-n |
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option, this is the cache size |
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.I per parallel process. |
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Cache performance is less sensitive to this parameter, |
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and reasonable performance can obtained with as few as 10k photons. The |
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default is 1M. This option recognises multiplier suffixes (k = 1e3, M = |
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1e6), both in upper and lower case. |
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.TP |
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.BI -me " rext gext bext" |
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Set the global medium extinction coefficient to the indicated color, |
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in units of 1/distance (distance in world coordinates). |
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.I \-dv |
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option (above) may be used to override this. |
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.TP |
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.BR \-u |
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Boolean switch to control uncorrelated random sampling. |
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When "off", a low-discrepancy sequence is used, which reduces |
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variance but can result in a dithered appearance in specular highlights. |
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When "on", pure Monte Carlo sampling is used in all calculations. |
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.TP |
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.BI -lr \ N |
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Limit reflections to a maximum of |
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.I N. |
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> |
.I N, |
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if N is a positive integer. |
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If |
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.I N |
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is zero, then Russian roulette is used for ray |
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termination, and the |
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.I -lw |
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setting (below) must be positive. |
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If N is a negative integer, then this sets the upper limit |
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of reflections past which Russian roulette will be used. |
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In scenes with dielectrics and total internal reflection, |
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a setting of 0 (no limit) may cause a stack overflow. |
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.TP |
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.BI -lw \ frac |
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Limit the weight of each ray to a minimum of |
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.I frac. |
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During ray-tracing, a record is kept of the final contribution |
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a ray would have to the image. |
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If it is less then the specified minimum, the ray is not traced. |
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During ray-tracing, a record is kept of the estimated contribution |
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(weight) a ray would have in the image. |
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If this weight is less than the specified minimum and the |
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.I -lr |
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setting (above) is positive, the ray is not traced. |
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Otherwise, Russian roulette is used to |
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continue rays with a probability equal to the ray weight |
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divided by the given |
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.I frac. |
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.TP |
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.BI -S \ seqstart |
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Instead of generating a single picture based only on the view |
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A progress report writes the number of rays traced, the percentage |
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completed, and the CPU usage to the standard error. |
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Reports are given either automatically after the specified interval, |
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or when the process receives a continue (-CONT) signal (see |
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or when the process receives a continue (\-CONT) signal (see |
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.I kill(1)). |
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A value of zero turns automatic reporting off. |
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.TP |
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The default is to print warnings, so the first appearance of |
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this option turns them off. |
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.SH EXAMPLE |
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rpict -vp 10 5 3 -vd 1 -.5 0 scene.oct > scene.pic |
| 887 |
> |
rpict \-vp 10 5 3 \-vd 1 \-.5 0 scene.oct > scene.hdr |
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.PP |
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< |
rpict -S 1 -o frame%02d.pic scene.oct < keyframes.vf |
| 889 |
> |
rpict \-S 1 \-o frame%02d.hdr scene.oct < keyframes.vf |
| 890 |
> |
.PP |
| 891 |
> |
To render ambient illuminance in photon mapping mode from a global photon |
| 892 |
> |
map global.pm via one ambient bounce, and from a caustic photon map |
| 893 |
> |
caustic.pm: |
| 894 |
> |
.IP "" .2i |
| 895 |
> |
rpict -ab 1 -ap global.pm 50 -ap caustic.pm 50 -vf scene.vf scene.oct > |
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> |
scene.hdr |
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.SH ENVIRONMENT |
| 898 |
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RAYPATH the directories to check for auxiliary files. |
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.SH FILES |
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< |
/usr/tmp/rtXXXXXX common header information for picture sequence |
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> |
/tmp/rtXXXXXX common header information for picture sequence |
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.br |
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rfXXXXXX temporary name for recover file |
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.SH DIAGNOSTICS |
| 913 |
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.SH AUTHOR |
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Greg Ward |
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.SH "SEE ALSO" |
| 916 |
< |
getinfo(1), lookamb(1), oconv(1), pfilt(1), pinterp(1), pmblur(1), |
| 917 |
< |
printf(3), ra_rgbe(1), rad(1), rtrace(1), rview(1) |
| 916 |
> |
getinfo(1), lookamb(1), mkpmap(1), oconv(1), pdfblur(1), pfilt(1), |
| 917 |
> |
pinterp(1), pmblur(1), printf(3), ra_rgbe(1), rad(1), rpiece(1), rtpict(1), rtrace(1), rvu(1) |
