Approximation of Images
Recently, one of our customers reported a serious issue with the import of large IGES files (~6000 surface patches) in CAESES®. The import was quite slow, and a subsequent shift transformation for optimization purposes almost impossible. After a quick debugging session, we found the bad boys for this behavior and fixed the problems. As a positive result, the accelerated import will now also effect other import types (SAT, STEP, Parasolid) in the upcoming version 4.0.4.
This is the good news. And the bad news? You have to learn something new — but relax, it’s only a very small thing:
Number of Approximation Points
If you apply shift transformations or deformations to your imported surfaces, there is a new attribute now that you have to know: The “Number of Approximation Points”. It controls the accuracy of converting the original surface into the transformed NURBS version. So far, this has been an internal default value (e.g. 100). We kept it very high to prioritize the accuracy. However, in some situations, the accuracy is far too high (e.g. for very simple surfaces), and it slows down everything. This was the case for our customer, when the engineers tried to shift 6000 surface patches at once.… With this new option, the accuracy can now be lowered down to an acceptable level, so that it still balances the shape accuracy with regards to the transformation performance.
This is now available for image surfaces and image surface groups, and taken into account only for shift transformations. For translation, rotation and scaling this input is not used.
Sorry to all our users who observed this painful behavior, it has been a side effect of our new geometry kernel that we introduced some time ago. And thanks for reporting it! Don’t hesitate to get in touch with us if you have questions about this detail. It is merely a small one, but it can be an important one!