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In order to get more accurate Iso-Area results, users may need to densify their Network Layer input using the Densify by interval algorithm.
I tested the algorithm by constructing a few very long lines with few vertices and calculating Iso-Areas at intervals that would fall in between distant vertices. Since the algorithm first calculates a point cloud using all the vertices in the network and does not create any new points , it means that the outer-most iso-area contour or polygon may underestimate cost by as much as the longest segment of a line.
Most network inputs will already have reasonably dense vertices: this is only a problem if you have some very long, straight line segments.
E.g. see below, the 2500m Iso-Area point cloud and interpolation originating at the red hospital icon:
and the same result after using Densify network:
(I'm not sure what happened to the interpolation at the southern end of this figure... there are rows of nodata, but nonetheless you can see the difference in the point cloud)
The text was updated successfully, but these errors were encountered:
Thank you for pointing this out - I will still mark this as wontfix because it is the users responsibility to prepare his/her datasets in a reasonable manner (in the same way as with adding reasonable cost values or oneway information). This case is certainly not a common one and therefore has to be preprocessed by the user. Furthermore, adding the parameters for a user side densification would result in unnecessarily complex algorithm input UIs (...and they are already pretty complex).
In order to get more accurate Iso-Area results, users may need to densify their Network Layer input using the Densify by interval algorithm.
I tested the algorithm by constructing a few very long lines with few vertices and calculating Iso-Areas at intervals that would fall in between distant vertices. Since the algorithm first calculates a point cloud using all the vertices in the network and does not create any new points , it means that the outer-most iso-area contour or polygon may underestimate cost by as much as the longest segment of a line.
Most network inputs will already have reasonably dense vertices: this is only a problem if you have some very long, straight line segments.
E.g. see below, the 2500m Iso-Area point cloud and interpolation originating at the red hospital icon:
and the same result after using Densify network:
(I'm not sure what happened to the interpolation at the southern end of this figure... there are rows of nodata, but nonetheless you can see the difference in the point cloud)
The text was updated successfully, but these errors were encountered: