Large OS -> Top Layer Oogy

[PenskeGuy]

I'm running a series of parts with 1.4.5.10 in order to evaluate the Loop Gap, and found an anomaly. For these parts, run with natural PLA, I am introducing an optical effect by slicing a fine rez model but lowering the Oversample Resolution, such that the light rays are refracted in a wider dispersion, due to the inner and outer wall surfaces not being parallel. Using a lower OS, however, causes the upper-most layer to drop resolution near to that of a Skirt. All lower layers are as expected, but the top layer goes raspy when OS >= 0.2. Probably is happening at 0.1 (anything > 0.0 makes logical sense) but is at an amount that is masked by the path display resolution aliasing.

[lonesock (Jonathan)]

Is it possible that the top surface is sitting exactly on a slicing plane?  When that is the case, KISSlicer samples the 3D distance to the object and gets a bunch of 0's right where the top surface is, so it has "we are outside" information, but no useful "we are inside" information.  As a test, can you change your slice thickness a tiny bit (like 0.2 mm goes to 0.21 or 0.19).  I still need to think of a good way to handle this particular issue in the general case.

thanks,

Jonathan

[PenskeGuy]

Exactly right. Change to 0.24 or 0.26 and the top layer resolution is smooth.

[lonesock (Jonathan)]

OK, thanks, I will put it back on the ToDo list.

Jonathan