Advanced Unit Settings Dialog

Contains controls for setting the resolution of the design environment, which sets its size and accuracy.

You can access this dialog from the following:

Design File Settings dialog: select Working Units and then click the Edit button

Setting	Description
Unit Type	Determines if the units in this design file are units of measurement or some unit-less representation. Distance — Units are a unit of measurement. Unit-less — Units are something other than a unit of linear measurement. For example, Longitude or Latitude.
Resolution	Determines the accuracy of the design plane/cube. The Resolution setting defines the worst case accuracy for the design environment, which occurs at the very outer limits of the (very large) working area/volume. For example, working to a "worst case" accuracy of 0.0001 meters, the size of the design plane/cube is 900 million kilometers along each axis. Actual accuracy is many millions of times better when drawing near the origin of the design plane/cube, which is the usual situation. CAUTION: Changing the Resolution setting, changes the size of existing geometry in the model.
Working Areas (each axis)	Displays the length of each axis of the working environment (expressed in Miles or Kilometer when Unit Type is Distance) depending on the resolution. This area is recalculated, automatically, if the resolution is changed.
Working Areas (Solids)	This setting is required by the Parasolid solids modeling engine used by the product. It defines an upper bound that limits the extents of any single solid such that it can be modeled to a fixed precision. This precision value is displayed in the Advanced Unit Settings dialog as "Solids Accuracy". What settings you use will depend on whether or not you require compatibility with V7 projects. For best results: In the Resolution section, set storage unit to Meter. In the Working Areas (each axis) section: For V8 projects: Input 1 (Kilometer) For V7 projects: Input 0 With V8 projects, this will set the Solids Accuracy to 1E-008, which also is the Parasolids default. If you then make any changes to the Resolution setting, changing the Solids value back to 1 Kilometer will restore the Solids Accuracy to 1E-008. When you first access the parametric feature tools, in a model for which the Solids Accuracy has not been set, it defaults to the V7 settings. In these cases, an Alert box appears to notify you that the Solids Accuracy of the model can be improved (for V8 projects). It gives you options to update the setting, leave as is, or do nothing for the current session (so that the alert will appear in a future session with the same model). With V7 projects, after entering and accepting 0 for the solids value, the next time that you enter the Advanced Unit Settings dialog, the Solids value will reflect the size of the V7 design cube. When working with parametric elements or features, the Parasolid engine deals with precision issues as follows: All calculations for solids are performed to fixed accuracies called the session precision and session angle precision. In the product's environment, session precision equates to Solids Accuracy, which is determined from both the Resolution setting and the Solids setting in the Advanced Unit Settings dialog. Because solids modeling is very precise, it is important that design data is constructed at an accuracy that is at least as accurate as that required by the solids. With solids modeling: Session precision (or Solids Accuracy) is the linear precision of the modeler. Distances less than this value are treated as zero and distances that differ by no more than this value are treated as equal. Typically, points are not considered coincident unless they are less than 1.0E-8 units apart (linear precision). Session angle precision is the smallest angle (in radians) that is treated as different from zero. Angles less than this value are treated as zero and angles that differ by no more than this value are treated as equal. Directions are considered to be parallel if they differ by less than 1.0E-11 units. If possible, in order to enhance the reliability of solids, it is also recommend that you do not construct solids with geometry dimensions at or near to the linear and angular precisions. That is: Vertices that are not intended to be coincident are separated by more than 100 times linear precision (10-6 for session precision). Edges that are not intended to be parallel are separated by more than 100 times angular precision (10-9 for session angle precision). To handle the precision of arcs correctly, the radius used when creating an arc must be less than a factor of 10 times the dimension of the size box.