I am modelling a section of an airport check in area. If I use round objects elliptical - flat for all large vertical support columns the calculation time is 4.5 hours. If I remove the columns the calculation time is 1 to 2 minutes. Surely the calculation routine for round surfaces can be simplified. Please advise if there is a way around the problem.
One possible factor is the setting for 'Initial Curve Increment', in the Advanced Settings dialog box.
It's got a figure of 15, which means that when it gets a curved, circle or elliptical object it breaks the curve into flattened surfaces at 15 degree increments. So an ellipse or circle which encompass 360 degrees are broken into 24 surfaces, but if you changed it to 30 degrees (and re-created the objects, as changing the figure does not retroactively change previously created objects/rooms) you would get it broken down into 12 surfaces.
A rectangular room has some reasonably simple sets of trigonometric calculations between fixtures and surfaces, but if you go adding in ovoid elliptical curved surfaces you're going to add to the calc time.
Whether this truly accounts for the time blowout you're seeing I can't tell - it may be another factor (perhaps you've got hundreds of these support columns).
I do know that I got a little intricate on some custom symbols for highways one time and using a low number for initial curve increment really took its toll on calculation time and even preparation time for calcs (such as going into render mode). Putting a higher number into the initial curve increment definitely reduced the calc times, and you can't tell the difference in the renders of the fixtures.