By choosing the analysis of upskins and downskins, you can identify the top and bottom surfaces of your part. You find out precisely which surface areas of your part are below a certain angle in relation to the bottom plane of the platform (X/Y plane). All areas below this angle are either an upskin or a downskin, depending on their orientation upwards or downwards.
This analysis can be very important, as, for example, some production methods have a different quality for upskins and downskins and it may make sense to rotate parts to minimize those areas.
In a dialog box, you can enter the settings for the up/downskin analysis. First, you can tick boxes to analyze upskins, downskins or both.
To the right, enter the threshold angles. If you enter 0°, only absolutely flat areas will be defined as upskins and downskins. If you enter 90°, everything between the flat areas and horizontal planes are defined as upskins or downskins.
In the parameters, you can edit the minimum component size and choose to filter small triangles:
The minimum component size determines how big the upskin or downskin areas must be. Sometimes, it is possible that very small areas, for example single triangles, are within the specified angle. If the size of connected upskin or downskin areas is below the minimum component size, the areas are not classified as upskins or downskins.
The dialog box for the Upskin and Downskin Analysis.
With Filter small triangles, small triangles which are within an upskin or downskin area, but which are not within the specified angle, are filtered and are still classified as upskins or downskins. That way, wrongly oriented triangles, like greases or similar, do not disrupt the upskins and downskins.
In the analyses screen, the main area of the part is grey, the upskins are green and the downskins are red. In the tabsheet, you get a field for the analysis, where, for both upskins and downskins, the angle, overall area and number of components is specified and you get single fields for all upskin and downskin components, in which their area is specified.
You always get back to this particular upskin/downskin analysis, if you click on it in the tree or in the tabsheet.
Left: The upskin of this sphere is colored green, the downskin is colored red. Right: This part has two upskin components.