|On this page|
This node can be used to measure the distance along a surface (aka the geodesic distance), which is useful for doing masking operations based on distance. It assigns to each point its distance to the point in the source group that is closest to it geodesically. Exact computation of distances along polygonal surfaces is computationally expensive. This node uses a method based on the heat diffusion to approximate these distances with often high accuracy. In addition, it allows for a natural smoothing of the computed distance field which, if calculated in full accuracy, may have cusps and sharp changes which could be undesirable for some use cases.
Points that are not reachable from any of the points in the source group will be assigned a distance of -1.
This method only works for distances along manifold surfaces, meaning distances cannot be tracked across nonmanifold edges or points. So, nonmanifold edges and points are interpreted as though being cut away from the surface, leaving narrow slits or tiny holes in their places.
This node is similar in function to Distance along Geometry which also approximates geodesic distances. It is expected to be considerably slower than Distance along Geometry, particularly if it is used only once (see the next tip) but it is more accurate and can handle complicated polygonal shapes better.
This node is particularly useful and efficient if the source points are needed to be modified frequently, e.g. in a loop network. It maintains a cache that allows it, upon modification to the source group, to recompute the distance field very quickly and with the same accuracy.
On very large meshes, the heat diffusion method may fail numerically, in which case it is possible that the results for points at a certain distance value or higher to be calculated incorrectly. In such cases, adding a little bit of smoothing can often resolve the issue.
A subset of points in the input geometry whose attribute value will be set. Leave this blank to affect the attribute value for all points in the input.
Start points to measure distance from.
This is the name of the distance attribute to create.
Control the smoothing of the generated distance values. Increasing the smoothing reduces the chances of numerical failure but makes the computed distance values less accurate. This may however be desireable since the true distance field tends to be naturally non-smooth at points which have two or more different shortest paths to the source set.
Boundary Balance (advanced)
Presence of surface boundaries may interfere with the discretization in the formulation of the heat method and affect the computation of the ditsnaces in the vicinity of boundary edges, particularly when very large amounts of smoothing is applied. In this case the natural tendency of the solution (balance value of 0) is to make distance levels to be orthogonal to the boundary curves. Alternatively, the node can force trivial boundary values (balance value of 1) which may appear unnatural. Nearly always, 0.5 will be the best balance.