Rhino claims 1 extra item than there actually are

So I have a very strange and very confusing problem.

I have exported a DXF from the software QGIS, this dxf is of building footprints.

Within the Qgis software it is a .gpkg vector file of polygons and states the “feature count” is 7519.
But when I export the layer as a DXF and then open it in Rhino, Rhino states there are 7520 hatches.

This is a huge problem when I am trying to extrude the buildings to a list of their heights and only have 7519 values for that so the data tree is ruined.

What is more bizarre is that sometimes when i select the all of the hatches in rhino it claims there are only 7519 hatches but then instantly if I deselect them and select them again it will say there are 7520.

I have done a number of things to work out what is happening:

  • SelDup - but there are no dupicates apparently.
  • I exploded the hatches and then checked the bounds of the areas of the surfaces (in GH), there was 1 surface with an area of 0.000807, but when i culled this from the list and baked the extruded geometry and cross checked the correctness of the building heights they was not the correct so I dont believe this tiny surface was the problem, because the item also showed up in the feature count in QGIS.
  • I have tried importing the dxf in all the different ways but no luck.

I have now run out of ideas and was hoping somone might have any thoughts.

Here is the .dxf attached.

GB-CMD_1_B_211115_OSOM2.dxf (2.8 MB)

Hi @samuel2
I see the same tiny sliver (in the upper left corner) and I suspect it’s the culprit. My guess is that it comes from QGIS and it somehow “offsets” the list of heights by being in the feature count, but not in the list of heights - and that is why you are seeing the buildings of the wrong height when you delete it. I would go back to QGIS and see if you can solve the problem there. Can you see if the tiny hatch has a height assigned in QGIS?
HTH, Jakob

Hi Samuel -

I can confirm that both Inkscape and DWG Trueview create 7519 objects from that DXF file.
And the tiny footprint is also present there - I’ve inserted a screenshot of DWG Trueview into the Rhino viewport and offset that a bit so that they are not in the way of each other. Next to the small Grasshopper green object somewhat in the center, there is a tiny spot from DWG Trueview:

At any rate, I’ve thrown this on the list as RH-66380 to be taken a closer look at by a developer.

Would there be any possibility of a “disjoint” hatch being split by Rhino or something like that? Don’t even know if that’s possible, but that’s one way one object could become two…

OK. I’ve narrowed down the problem. There is one entity that has 2 loops in it. Because the loops touch at a vertex the inner one is not treated as a hole and is added as a second hatch.

This is the “hole” loop. You can see it as a hole if you open in acad. Is that supposed to be there?