VW23 - changing units changes geometry / shading

[bjoerka]

does anyone else have seen something similar before?

i imported an ifc file from a client. quite heavy with 640mb. took about 30minutes. the building itself is an existing which is getting refurbed.

 

after the import the geometry was far of the internal origin. it took me several attempts to place the user origin near the geometry.

vectorworks sometimes suddenly blanks out the rulers, no geometry could be seen anymore and after selecting all on the active layer (wanted to zoom to activated objects) it crashes.

well after i managed to see the imported geometry i switched to shaded. my file was still in mm units and i switched to m units.

after that a prompt appears telling me the document is being updated. never seen this before. on the bottom right in the status line was written "geometry" and the green progress bar was running.

but on my screen i could see that each part of the geometry was differing from a second before.

after the process was done, which took about 6 minutes, my model looked different, but more complete but also things disappeared that are there in reality...

what´s the thing that it a) takes so long to change units in a cad system and b) that geometry can differ with two different unit settings?

i guess it relates to the distance to the internal origin, but how do i get an imported ifc file direct after import close to the user origin?

 

see the screenshots attached, that show the difference in shaded view.

 

first on is units set to millimeters

second one is units set to meter

 

 

 

 

 

 

Edited March 31, 2023 by bjoerka

[LarryO]

In the second instance you are decreasing the accuracy in the file and there likely numerous points close together given the file size. Those points may now be perceived as being in the same location but in reality are not, just very close together. When calculating the object geometry potentially small surface triangles are no longer perceived as have a surface area and curves are not curved anymore, etc and would be causing geometric calculation errors like division by zero, etc. and they disappear or appear malformed with one or more points placed near infinity. Similar issues can occur when exporting to dxf/dwg if you don't have accuracy to at least 6 decimal places when using imperial units. If you have the ability to exclude small items from an import/export of a site it can help. Things like screws, faucets and floor drains that may have been imported from a manufacturers' library which were created with very high or very crude definitions. I've also seen company logos and converted font characters cause numerous problems when they were flattened and embedded into the file somewhere.