I am looking to merge these two geometry together and create a smooth connection rather than a sharp edge. (As seen in the second image)
In the past I have been trimming, merging, and then filleting the resulting edge between them to create a smoother intersection where the two geometries morph into each other. In this case, the lateral brep has too many faces for that to be feasible.
Is there either a way to simplify the geometry on the right into one surface? Or instead some other way besides the fillet command to create a smooth connection? (Keeping as a brep vs mesh is not a priority, so a mesh solution would work too)
This method is crude, but works for your case. It boils down to finding the correct concave edge to fillet. I did it by trial & error, which is OK for this simple case, but I expect won’t work well for something like a bridge with potentially many such intersections.
