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2020-04-07
05:43 PM
- last edited on
2023-05-23
05:55 PM
by
Rubia Torres
2021-01-19 08:41 AM
2021-01-19 10:50 AM
2021-01-22 07:14 PM - edited 2023-09-10 07:07 PM
Archicad uses a surface modeler, which means that curved surfaces are approximate by 3D polygonal planes, and 3D curves are approximate by 3D lines. This is why you see that those curved geometries in 3D and in Sections look like they are segmented.
After a bit of research, I believe that curves defined in the Profile Manager are approximated in a similar fashion. Archicad has a built-in value of how much the lines/planes approximating the curves/surfaces can deviate from those curves/surfaces.
If you go to the Design > "Magic Wand Settings" Dialog, you will find that the "Deviation From Curves" option offers similar functionality, for example when you use the Line tool with the Magic Wand to approximate a curve.
What I just found now is that you cannot enter a value smaller than 1.0 mm into the "Deviation From Curves" options' "Less than" field. So Archicad has this hard-coded limit that you cannot approximate curves with lines so they deviate less than 1.0 mm from those curves.
Having such a limit may make sense since you would not want to allow people to set the value to 0.1 mm or 0.01 mm and then curves would be approximated my hundreds of lines, 3D curved surfaces would be approximated by thousands or tens of thousands of planes, and the program would quickly reach its limits in terms of polygon count in 3D.
The reason this is important comes into play when you have very small curves. When you have a curve with a 250 mm radius, Archicad can easily approximate it using 36 line segments (the default).
But when you have a curve with a 100 mm radius, Archicad can approximate it only with 24 line segments because if it used more segments, the deviation of the line segments from the curve would be much less than 1.0 mm. So Archicad calculates the lowest number of segments using which the deviation from the curve is less than 1.0 mm and uses that (or the default 36, whichever of these two values is smaller).
As you go smaller, Archicad can use a decreasing number of segments and still meet the above limitation. For example, if you have a curve with a 20 mm radius, Archicad can use only 12 line segments, if you have a curve with a 10 mm radius, Archicad can use only 8 line segments. I think 8 segments is the minimum Archicad will use to approximate a full circle. This is why you see that the smaller curved geometries are the more segmented they look because they bump into this limitation of the program.
It may worth noting that Archicad was meant to be an architectural program so its accuracies are set based on that. For example, in settings, you can set 0.1 mm as the highest accuracy in Working Units.
2021-01-28 02:10 AM
2021-01-28 12:39 PM
2021-01-28 02:57 PM
Jeff wrote:This was what Vistasp was suggesting by using the Magic Wand. You need to draw your circles (pipe in / out), then using the magic wand set to "Segments Along Circles" and a suitable value, you can then select the polyline tool and click on the circle to trace it using the Magic Wand. This will create a polygon to represent the circle. If you find the edges are too small to process then you can make the circles say 10x bigger, trace them and then reduce the polygon back to the required size. As far as I know the polylines should remain unchanged in the Complex Profile, although they will revert to separate line segments. Having got the polygons in the CP you can then create the required fill. I haven't used this for CP's but I do use it to improve curved profiles when using the shell tool.
...it would look better if the inner and outer curves of the pipe section had the same number of segments at least.
2021-01-28 11:49 PM
2021-01-29 02:38 AM
DGSketcher wrote:
This was what Vistasp was suggesting by using the Magic Wand. You need to draw your circles (pipe in / out), then using the magic wand set to "Segments Along Circles" and a suitable value, you can then select the polyline tool and click on the circle to trace it using the Magic Wand. This will create a polygon to represent the circle. If you find the edges are too small to process then you can make the circles say 10x bigger, trace them and then reduce the polygon back to the required size.
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2021-01-29 11:38 AM
Lingwisyer wrote:Ok back to square one... I am sure there was a thread about CPs, resolution and hidden edges not too long ago but I can't find it just now.
How do you deal with the edge lines?