Using the Curve Tool

PhotoModeler’s Curve tool is a useful and powerful modeling tool, but certain conditions should be met and certain steps followed in order to generate quality curves. To model a high quality curve, you must have a well calibrated camera and a proper set of photos. Curves are marked and referenced on two or more oriented photographs. The quality of the curve depends greatly on the strength of the camera orientation. A reliable camera orientation depends on a strong calibrated camera and accurately marked points.

A strong set of photographs is extremely important in calculating curves. PhotoModeler’s curve algorithms depend on strong angular separation between the photos as rotated about the object centerline. The angle ideally should be 90 degrees but you will get good results down to as low as 15 degrees. Curves can be complex – if it is a curve that changes directions considerably it will often have to be marked on three or more photographs. If it is a closed curve, it must be marked on photographs that view the curve from the same side.

You can check if your curves calculated correctly by doing any of the following:

1. Select the Curve on a photo and view the status bar at the bottom of the PhotoModeler screen. It will tell if you the curve is 3D or not.
2. View the results in the 3D Viewer. If they do not appear, they have not calculated. Check the angles of the photos. If only a part of the curve appears, try adding the curve to more photos.
3. Turn on Curve projections in the Visibility dialog. If the projections do not look correct, they have calculated weakly. You will need to add new photos that have better coverage of the curve.