CompuServe Messages

Rick, For my monitor / scanner a 8.5" X 6.3" photograph fills the background on a 3ds sceen. It may be the same for all but it may change for different scanners, I don't know. The important thing is to center the photo. If you stood in the center of a straight flat road and photographed the road aiming your real camera at the point where the road vanishes into the horizon, this point would be in the center of the photo and the paint lines would be ballanced on both sides of the centerline. Next, if you scanned this photo into 3ds and it tiled, the center of the photo would not be in the center of the monitor. Now assume you place the 3ds camera on the centerline of the model and adjust the camera so that the 3ds camera lines up with the offcenter vanishing point on the photo. The edges of the road will not be ballanced in the 3ds model as they are in the photo. You might be able to move the camera to the side of the road and fudge the error but you are not reprodusing the origional conditions. If the expert on the other side explained this to the jury he would probably feel better about his day in court than you would. Very ungood! The photo in step 2 is the photo or photos you use for the backgrounds. What ever you see in a photo is the light coming into the camera from a unique angle. Think spherical coordnates. You don't have to but, if you placed a long cylinder in the 3ds model, you could move and rotate that cylinder so that in the camera viewpoint you would see a circle, the end of the cylinder, on the point of interest in the photo. The cylinder is now covering all of the possible points where the light could have come from. Where the cylinder intersects an object, flat or hill or any 3d object is where the light came from. If you have two different viewpoints think of two cylinders intersecting and measure the x,y,z of objects that you have no measurements to. As with any triangulation, views at 90 degrees from each other are going to be most accurate. After using this method for awile I did find a paper on it S.A.E. paper930904 It explains the theory but l feel it has shortcommings on the practical application. Use his theory and my method.