In ship hulls, there tend to be large, regular areas that are easy to do and do not create great isocurve density. Here, the closest isocurve spacing is about two feet:
And if the surfaces will not join with a regular matchsrf, and when refine match is required to get them to join, the complexity surges. (EdgeSrf here, NetworkSrf actually produces a simpler surface.)
I assume by isocurve density you are actually concerned about control point density.
The number of control points in the results of EdgeSrf in each direction is determined by the degree of the curves on opposite sides in the direction, and their number of control points/spans of the curves, and the knot spacing if not uniform. The basic rule for degrees is each direction will be the degree of the higher degree edge in that direction. So if the edges in the u direction are degree 3 and degree 5 the surface will be degree 5 in that direction. The rules for number of control points are more complicated but can be summarized as the minimum number results when of control points when opposite edges are the same degree, have the same number of spans/control points and if non-uniform have the same knot spacing. Different degrees, number of spans/control points and/or knot spacing will increase the number of control points with a few exceptions.
The number of control points in the results of MatchSrf depend on the tolerances and the shape of the input curves. Tighter tolerances and greater variation in the shape of the input curves results in more control points.
Keys to reducing control point complexity of complex models are using a larger tolerance which will produce results which meet requirements, the modeling strategy both overall and in complex areas, and simplifying curves and surfaces where possible while maintaining the desired accuracy at every step of model creation and editing.
Attempting to match every offset of a boat or ship almost always leads to complex models, sometimes very complex models. The reality is the physical boat/ship almost certainly did not match every offset when built. Some enthusiasts might be surprised at how large the deviation can be. Whether the added complexity of matching every offset is worthwhile depends on the use of the model and the desires of the modeler.
It does make intuitive sense to keep things simple for Rhno.
Breaking a section into two spans, for example, could avoid seeming to ask Rhino to try to figure out how a flare of bow curve above the waterline relates to the curve of the bulbous bow.*
*for non-naval architects: itâs unrelated, so making that as clear as possible to the surface calculation seems like a good thing.
I donât think it has anything to do with âRhino-friendlyâ or not. Rhino is enabling you to do things to surfaces that alot of other CADâs simply canât do.
What arenât you liking about the isocurve âdensitiesâ? The lack of homogeneousness? You can possibly just match the edges in such a way that theyâre not so ârefinedâ. But you should also consider the results caused from what theyâre being matched to.
It is a bit strange that the density would increase as shown above, in cases where the density seems to increase alot relative to the adjacent surfaces. Iâm wondering if your object property density is 1:1 or not â on each entity.
Why match so âtightlyâ? Are you dealing with ânaked edgesâ that wont go away? Have you tried the ârebuildedgesâ command to find out if your edges are clean?
What degree srfâs/crvâs are you matching too? etcâŚ
Iâm not understanding what you mean to be âtangentâ here.
These all look almost to be âplanarâ and could be much less dense than they look here. Are you not wanting a single âtrimmedâ surface?
Yeah, many folks here like degree 5 srfâs trimmed to oblivion jk.
Idk, they do amazing things with deg 5âs.
I personally donât think thereâs a problem with density unless itâs used inefficiently or obstructing the ability to transform something, but managing the density is all thatâs necessary depending on the situation. You just have to know how to work with it when the situation arises to adapt it or change it. etc.
0.03125" is a large tolerance from a âmachinistâ perspective. The densities issue Iâm seeing would make more sense to me if you were trying to get say 0.0001" tightnesses.
Hence:
I mostly use deg 3. Only recently am I considering deg 5 cause the fancy stuff I see ppl doing here.
But I think itâs more of a short cut to avoid higher density degree 3âs, which I think are fine â imo.
If the network srf tools were more âfriendlyâ with deg 5, then Iâd probably started using higher degrees along time ago. But Iâm pretty sure ânetwrksrfâ turns everything into deg 3 ⌠hence, why I mostly use deg 3
Without seeing an uploaded sample or something, itâs hard to speculate, but thereâs definitely nothing wrong with rebuilding the surface to something that is still within tolerance.
âRebuildingâ is a common part of most of my workflows. I usually prefer homogeneous isocurve density, but it all depends on whatâs necessary for the job at the time.
Sometimes fitting a surface really tight is inevitable if you want the single surface to conform to other adjacent geometry.
jk.
