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Text File | 1994-10-25 | 17KB | 372 lines

RAYSMITH v 1.0 August, 1994 -by Eduardo Bustillo Iceta- 1.INTRODUCTION RAYSMITH is a radiosity and ray tracing program that allows the user to create impressive 3-D images. It was created as an end of university project for my six year degree in mechanical engineering. The program will be released as freeware and its continuity and support will depend on public acceptance. RAYSMITH's main characteristics are: -Geometry input: The geometry file is read from an Autodesk 3D-Studio v2 .3DS file. This provides a very good geometry creation interface, as well as DXF importing facility (in 3DS, not in RAYSMITH). -Radiosity calculations: Implemented using Monte Carlo integration. This permits to have colour bleeding between surfaces, penumbras, refracted shadows, specular and diffuse reflections, blurry reflections, translucency and refractions, texture mapping and any geometry of light sources. The 'disadvantage' is that you won't get sharp shadows as in a pure ray-tracing program. -Adaptive subdivision: Objects with big radiosity gradients inside are dynamically subdivided during the radiosity process. -Ray tracing: A postprocess of ray tracing is used to get the view independent information obtained and create the image file. Among the main characteristics of the algorithm used are: -Depth of field: The camera is not a pinhole model, and it has a user selectable lens radius. -Stochastic anti-aliasing: This eliminates aliasing in a great deal. -Stereo view: As an option you can obtain an image that can be watched with red-green stereo glasses for a more impressive 3-D effect. -Acceleration techniques: Three different techniques are incorporated into RAYSMITH. This makes it one of the fastest programs I have tried (POV 2.2, RAYSHADE, RTRACE...). -Graphic formats: RAYSMITH works in 16.7M colours and only the uncompressed 24 bit TARGA file format is supported. If you want to use files with other file format for textures, you should get ALCHEMY or any other good format exchange program. -Limitations: There are no resolution, number of objects or any other kind of limitations in the program. No arrays have been used in its programming so every piece of memory is dynamically allocated. With the usage of a 386 and a DOS extender compiled version any scene can be rendered. -Minimum system required: IBM-PC compatible with a 386 & 387 or better CPU and 2Mb of RAM. It is recommended to have at least 8Mb of RAM if you're planning to do serious work. It works anyway but disk accessing becomes irritating. -Completely written in ANSI C: It doesn't help in speed but it may be compiled for almost any other platform (DEC OSF/1 and HP-UX versions have been compiled with no modifications). 2. AVAILABLE VERSIONS At present there are two versions available: -GNU gcc 2.6.0 compiled version: It uses DJ Delorie's GO32 DOS extender which provides up to 256Mb of virtual memory. It works under DPMI, but it's faster when DPMI is disabled. -WATCOM C v9.5 compiled version: It provides only 32Mb of virtual workspace and its much bigger as it needs to include the DOS4GW extender. It is slightly faster in the radiosity process but has slower parsing and similar ray-tracing benchmarks. The only difference is that it outputs memory statistics as the program is executing. This lets you know the amount of memory required for rendering a file. 3. COMMAND LINE OPTIONS AND REQUIRED FILES These are the included files in the compressed package: RAYSMITH.EXE -Executable- RAYSMITH.DOC -This file- RAYTRACY.EXE -Distributed raytracer with diffuse effects- RAYTRACY.DOC -Documentation for RAYTRACY- TEXTURES.RAY -Material translating file- DOS4GW.EXE -Only in the WATCOM version- GO32.EXE -Only in the GNU gcc version- MLI2RAY.EXE -3DS material library to TEXTURES.RAY translator- Command line options: RAYSMITH.EXE filename.OPT You don't have to create long command line scripts to activate RAYSMITH's options. Once you have your geometry file, you must create a .OPT text file where you include the options that will be used for rendering. .OPT format: The .OPT file is an ASCII file in which there is an option in each line. INFILE=filename.3DS Here you put your geometry file name. OUTFILE=filename.TGA Output file name. If omitted, the default name given to the file would be the input file name with its extension changed to TGA. HRESOLUTION=640 (default) Horizontal resolution of the image file. There are no limits (only your available time). VRESOLUTION=480 (default) Vertical resolution. MIN_BOUND=0 (default) This affects acceleration. Possible options are: 0: No minimum bounding volume of global scene is computed. 1: Minimum bounding volume is computed and consequently a coordinate system change is performed. Explanation: When objects in the scene are axis aligned, the minimum bounding box has its planes perpendicular to the coordinate system axis, but when objects are in arbitrary positions a coordinate system change must be performed to permit an axis aligned box be the minimum possible bounding box. So, when you have an scene aligned, put 0 (it will be faster), but if the objects are not aligned, use 1. TURBO=0 (default) If 1, computation is much faster. RAYSMITH will try to create a Z-Buffer structure to accelerate calculations. If there's enough memory in your system, ray-tracing may be 3 times faster than usual. VOXEL_RESOLUTION=6 (default) There are two acceleration schemes selectable by the user: -Adaptive Voxel subdivision: Subdivides the space in a tree of voxels adaptively depending on the number of objects inside. It is faster if used wisely, but consumes more memory. A good parameter selection could be: VOXEL_RESOLUTION=6 (or 8) VOXEL_DEPTH_MAX=2 -BOP (Binary Object Partitioning): Creates a tree of planes subdividing the space so that equal number of objects are in each side. This variable "VOXEL_RESOLUTION" affects the number of voxels that are in each step of the subdivision. If you put 10, you will get 10*10*10=1000 boxes each time a subdivision is performed. VOXEL_DEPTH_MAX=2 (default) Maximum depth of the voxel tree. VOXEL_OBJECTS_MIN=16 (default) If VOXEL_OBJECTS_MIN number of objects is reached in a voxel, subdivision is stopped, even if the maximum depth hasn't been used. -Note: If any of the above options concerning voxels is indicated, voxel subdivision will be used as the accelerating technique. If only BOP options are specified, a BOP subdivision scheme is used. If none of the options is selected, the default is voxel subdivision.- BOP_OBJECTS_MIN=12 (default) Minimum number of objects in each leaf of the tree that stops subdivision. BOP_DEPTH_MAX=100 (default) Maximum depth of the tree. If you use a big one (200), the program will never reach it as subdivision stops when it isn't efficient. MAX_NUMBER_RAYS=8000 (default) This is the initial number of rays that will be shot from the lights in the scene. 8000-20000 should be enough to assure a good solution (depending on the number of triangles in the scene). For quick previews 2000-4000 is enough. When adaptive subdivision is activated you should increase this value. MAX_DEPTH=5 (default) Maximum depth of rays shot (if their energy is still enough). For scenes with diffuse and specular reflecting objects 2-3 is enough. When using transparent materials it should be increased to 4-5. INSIGNIFICANCE_THRESHOLD=0.01 (default) Ratio between the ray's energy and its initial energy to stop propagation. BRIGHTNESS=80.0 (default) Used to brighten up scenes that are too dark to watch. It is recommended to use a low resolution to calculate the scene fast until the right level of brightness is found. ADAPTIVE=0 (default) If 0, adaptive subdivision is off. If 1, it is on. SUBDIVIDING_AREA=0.1 (default) When (triangle_area)/(average_area) is higher than SUBDIVIDING_AREA, subdivision may be performed if necessary. DEPTH_OF_FIELD=0 (default) If 0, depth of field is off (pinhole camera). If 1, it is on. LENS_RADIUS=0. (default) Option read only if depth of field is on. ANTI_ALIASING=0 (default) Number of rays per pixel. Possible values: 0->One ray per corner of pixel. Pixel colour averaged. Fast and gives good result in scenes without blur or depth of field. >0->n rays per pixel following a pseudo-Poisson distribution. When using blurry materials or depth of field you should use a high value to achieve good quality. STEREO_VIEW=0 (default) If 0, a normal image is generated. If 1, 3-D red-green stereo glasses must be used to watch it. EYE_SEPARATION=6 (default) Affects the Stereo view option. Example of .OPT file: INFILE=test.3ds HRESOLUTION=640 VRESOLUTION=480 TURBO=1 VOXEL_RESOLUTION=6 VOXEL_DEPTH_MAX=2 VOXEL_OBJECTS_MIN=12 MAX_NUMBER_RAYS=8000 MAX_DEPTH=3 INSIGNIFICANCE_THRESHOLD=0.005 BRIGHTNESS=90.0 ADAPTIVE=1 SUBDIVIDING_AREA=0.01 DEPTH_OF_FIELD=1 LENS_RADIUS=6.0 ANTI_ALIASING=16 4. TEXTURES.RAY This file must be present at runtime for the program to work correctly. It is an ASCII text file with the translation table of the materials used in 3DStudio. Materials in RAYSMITH have additional properties, and this file contains them. NAME TYPE REFLECT SR DR IOR BLUR TRANSM ER EG EB "MIRROR" 0 1 1 1 1 0 0 0 0 0 0 0 0 0 | | | | | | | | | name of the material in 3DStudio between "" | | | | | | | | | | | 0 means pure colour, while 1 means texture mapped material | | | | | | | reflectance of the material in the Red Green Blue bands (max. 1 1 1) (min 0 0 0) | | | | | | | | Specular reflection index (0->1) | | | | | | Diffuse reflection index (SR+DR | should be 1) | | | | | | Index of refraction (only | useful if transmittance >0)| | | | Blur: Value between 0->1. 0 means perfectly specular reflection of specularly reflected rays. 1 means diffuse reflection of specularly reflected rays. It affects specular reflection and transmition making them less sharp. Good values for metals are between 0.0005->0.0001. Higher values give unrealistic results. When this value is not 0, anti-aliasing should be 15 to 40 to give the best results. | | Transmittance: Part of the incident energy that is left to | pass in each frontier. Again in the R G B bands. | | R G B Energy emitted by the material. This is the way to define lights in RAYSMITH. Create objects with this material, and they will be lights of any geometry. There is a TEXTURES.RAY example file included in the package so that you can experiment with it and create your owns. Another late hour facility has been included in the package: MLI2RAY.EXE This program lets you convert automatically 3DStudio material libraries (extension .MLI) to TEXTURES.RAY files so that you are able to use any already created material. Usage: MLI2RAY.EXE material_file without extension. It will create a file called material_file.RAY that you will have to rename as TEXTURES.RAY and retouch by hand. 5. CREATING GEOMETRY FILES As it was said before, geometry files have Autodesk's 3DStudio .3DS format. So if you want to create any scene you must have access to it. The only incompatibility with this format has to do with lights. Lights in 3DStudio are point lights, and as RAYSMITH is a radiosity program, it cannot use these lights. To create lights for RAYSMITH you have to assign a luminous texture to the object you want to have as a light. RAYSMITH is a radiosity program so it is difficult to obtain sharp shadows. One reason for this is that lights are not point lights, but the most important one is the polygons size. Using small polygons in shadow boundaries will give the best results, but this is difficult to do when creating a scene the first time. It was because of this that I added a sort of rudimentary adaptive subdivision scheme. Even in scenes with great radiosity gradients and relatively low polygon resolution it gives acceptable results if wisely used and combined with a manual pre-subdivision. Well, it's up to you to send me suggestions and own experiences to improve it. 6. CONTACTING THE AUTHOR I would appreciate any scenes, high-quality renderings, TEXTURES.RAY files, suggestions or comments that anyone interested may send me. Any bugs will be welcome. My address is: Eduardo Bustillo Iceta Part. de Basterra 1 48990 GETXO (VIZCAYA) SPAIN You can also reach me at the following Internet address: (Please only send me messages here): epabuice@s835cc.bi.ehu.es Letters in spanish, english or french will be answered. Have fun! 7. LEGAL INFORMATION DISCLAIMER This software is provided as is without any guarantees or warranty. Although the author has attempted to find and correct any bugs in the package, he is not responsible for any damage or losses of any kind caused by the use or misuse of the package. The author is under no obligation to provide service, corrections, or upgrades to this package. Permission is granted to the user to use RAYSMITH to render images. The use of this software for the purpose of creating images is free. The creator of an image retains all rights to the image created and may use it for any purpose. This software package and all of the files in this archive are copyrighted and can not be distributed or modified without the written permission of the author Eduardo Bustillo Iceta. No portion of this package may be separated from the package and distributed separately without the written permission of the author. This software may not be included in whole or in part in any software without the written permission of the author. This software may not be included in any publication, such as, but not limited to, magazines, books, newspapers, or newsletters, without the written permission of the author. This software may not be included in any software compilation using media such as, but not limited to, CD-ROM, tape backup, optical disks, hard disks, or memory cards, without the written permission of the author.