CompuServe Messages

Rick, and Nancy Fulton for your next book if you are out there, I am an Engineer working near Albany, NY. While I am sure that I will continue to learn this is how I take measurements from photographs with 3ds: 1. Find the size of the background on your monitor. Do this by scanning graph paper into a tif file, bringing the tif file in as the background and rendering the scene. Count the squares on the graph paper to determine the size of your background. Write this down and save it. 2. Scan a photo into a tif file the exact size as your background. This will require adding a border on two sides and scaling the photo up. The important thing is to have the photo centered on the screen when it is rendered Do not trim and do not allow more than minor tiling as the photo will not be centered. 3. Create a 3d model of the scene. I use auto cadd and dxf into 3ds. The data for the model usualy comes from record plans, surveys or measured points in the field. 4. Cover the 3d objects, usually the road / curb /tree trunks /poles with a material and modify the material in the scene to a 50% transparency. 5. Bring the police photos of the scene in as backgrounds as described above. 6. Create a camera. 7. As you know manual methods involve marking grids on an uncut photo to a vanishing point (center of photo).It is still best to have an uncut photo for the background but if it was basically cut out of the center of the origional negitive it will work. The center of the photo is the place in the model were your camera target should be. Place the camera about where you think the photographer was when the photo was taken. using the photo as the background render the scene. 8. You will see the background through a 3ds model. Adjust the camera position, target position and lens untill the two match up. You are in the same position as the photographer. 9. Objects on 3d surfaces (skidmarks) can be measured by placing an object on the surface and then viewing from above. Objects in space need to be set up with photos from 2 angles. I hope this helps, John