Question
"I have performed a Grid Raytrace in my model, and TracePro is reporting multiple "overlapping object" error messages. I have looked over the geometry, and there are several coincident surfaces, but no overlapping objects. What is causing these error messages, and how can this be resolved?"
Synopsis
Overlapping Object Errors with Grid Raytrace
Solution
"I do not believe there is really any overlapping geometry in this model. The problem is a result of the "well-organized rays" of the Grid Raytrace. To analyze the problem, I inserted small spheres in the model at the locations described in the error messages. The spheres are all at "seams" on the grid of objects (view model in X-Y). When a ray enters right at the seam, TracePro is not able to determine if it should be entering one of the adjacent objects or the other. With a set of random rays, it is nearly impossible for a ray to be incident precisely on this seam, but with a Grid Raytrace, it is not. To see this, I changed the Grid Pattern from Circular to Random, and I was able to trace 10,000 rays without an error. Another test is to leave the Grid Pattern as Circular, but to set the X and Y coordinates of the origin to be .001, rather than exactly "0". This ray trace also results in no errors. The solution to this problem is to trace a "realistic" set of rays and avoid the "unrealistic" problem of rays incident exactly at the seams between the objects.
