EMAIL:avara@aydin.com NAME: Al Vara TOPIC: Night COPYRIGHT: I SUBMIT TO THE STANDARD RAYTRACING COMPETITION COPYRIGHT. TITLE: Bad Night COUNTRY: USA WEBPAGE: none RENDERER USED: Povray 3.0 for DOS TOOLS USED: Corel 5.0 Win, Moray 2.5 for DOS, Terrain Maker 2.0 DOS RENDER TIME: 6 Hours 5 Minutes 27 Seconds HARDWARE USED: 486DX100, 8 MB RAM IMAGE DESCRIPTION: My vivid memory of the surprises in the night. It was the first image that entered my mind. I could not imagine tring to capture this subject matter in any of my other favorite medias: pencil, pen & ink, or watercolor. Photography presents significant undesirable drawbacks too, if you get my meaning. DESCRIPTION OF HOW THIS IMAGE WAS CREATED: This is the second POV raytrace I have attempted, so I did a lot of problem solving that I am sure is old hat to most of you. I'll describe my efforts to help other newbies. The mirror was easy to build (three flat shaped sweeps), but hard to align. I went through a lot of trial and error until I developed a technique. I made a mirror group to allow rotations about the group center, rather than the origin. Pointing the mirror was made easier by temporarily adding a high ambient sphere near the mirror and in line with the desired center of the police car image. This made finding a reflection easier. Successively moving the sphere back clearly showed the direction for the necessary mirror rotation improvements. The police car started as a Corel clipart of a taxi. I made a mask of the car shape in black and white and used it to produce a heightfield, with a waterlevel set to leave the car shape. Placing the headlights (spotlights with high ambient cubes) was a nightmare of trial and error. Then I got smart and added the headlight opening to the outline mask. Now the headlights were moved behind the opening in the heightfields and alignment was automatic. The resulting police car image is flat, but being dimly lit with all that surrounding glare, it seemed passable. The rotating police lights are colored spotlights centered inside of semi- transparent cubes which have high ambient. Tilted, white disks were added to simulate the internal light reflectors. Finding the best rotation angles was fun. Playing with the atmosphere was sheer magic. The speed sign started out as a Corel clipart. A high ambient image map makes it seem like it had reflective paint. Early in my creating, I developed a great heightfield for the roadside cliff using Terrain Maker. As more complex shapes were added to the project, I ran out of memory. Weeks were spent trying to find a way to only use the front portion of the heightfield instead of the full 512x512 file size. I was never able to achieve complete success but I'll describe the method that worked best for me. If anyone knows a better way, let me know. If anyone wants a description of what doesn't work, I can bore you ad infinitum. The output of Terrain Maker is a GIF file. If you use a colored version, you get random color indexes assigned when you import the image into Corel. These color indexes become the height values, so using color is a no-no. Fortunately Terrain Maker lets you steal a color pallette and apply it to its images. In a 8 bit grayscale image, I drew a gray shaded fill using all 256 values. This was saved as a GIF. In Terrain Maker, I opened my cliff file, then changed the color map to that of the all gray GIF. This was then saved. This GIF has gray indexes corresponding to the height 256 possible height values. In Corel this image was cropped, converted to 8 bit gray scale and saved as a TGA (TGA format allowed easier positioning later, since Moray can read and display TGA, but not GIF). You would think I had a perfect cropped image at this point, but using it in leiu of the full image showed unsightly distortions, after I re-scaled the heightfield volume to compensate for the cropping. The good news is that I had saved enough data points to fit everything into memory at the same time. I had to go back to Corel and do a minimal blur on the cliff image data. This lost me the nice rocky edges Terrain Maker had provided, but the overall shape was still there. I played with the texture and normals to get some of the rocky appearance back. The car hood and dash are patches. To reduce memory demands and take advantage of the symmetry, only the left halves were modeled. A reference copy of each was made with a negative scale value to reverse it. Grid snap lets you butt the halves perfectly. POVRAY complained when I used the patches in a CSG, trying to cut the hood and dash along the same oval shape, but it did a fine job. Other cuts were made in these CSGs to provide more details. Black blockers were needed behind these cutouts to prevent underlying surfaces fropm showing through. Grass is hard to do. Heightfields made from random dots looked poor. Texture controls I tried did not come close. I settled for a tiled Corel photo of some grass. The image was not seamless but the low angle and some games I played adding normal wrinkles, hid most of the tile edges. If anyone has a better way, pass it along. I'll list some other tricks I taught myself along the way to help other newbies get started. 1) Always do a small 80x60 thumbnail image before a bigger rendering. It catches lots of problems and saves wasted time. 2) Extra cameras don't take much memory and are great for evaluating complex 3D shapes. Use them all over. 3) On slow computers, put a few objects into a temporary group and use the Moray "file - save select" feature to make a test model. Unfortunately the camera cannot be put into the temporary group, so write a note so you can re-create it in the position and angles you need. Now work on just these objects, without the rendering overhead of all the other the objects. The group can then be merged back into the original model after your refinements are finished. 4) When your limited RAM computer complains of running out of memory while rendering using Moray's render button, don't give up. Export the POV/INC files instead of rendering and then exit Moray. This frees up the memory Moray holds on to. Now move to the directory you exported the files to and start the POVRAY from the command line prompt. 5) Povray has a feature that lets you final render just a samll portion of the image. I would have never completed this in time without it. 6) When your new at something, you never know if something is too hard to do, when you start. Use that as an advantage. Come up with your image without concern for the work involved. In the middle of this project, I had my doubts my little computer could ever finish the job. But wanting to create my vision bad enough, helped me fight through all the problems.