Spline Interpolation
Points Per Segment
DSFL data files may contain spline features, which are intended to be displayed as smooth curves. Since most GIS formats do not support splines, the FME will turn the spline into a normal line, and approximate the spline curve by interpolating additional points between each value. Larger values create smoother curves, and larger resulting output files.
Output Origin Data
Determines whether or not the origin data is output as a separate features.
By default, this parameter is not selected, so the origin data is merged with other data features.
If this parameter is selected, origin data is output as dsfl_origin feature type, with each feature having its unique index number in dsfl_record_index_number attribute.
Use Search Envelope
Using the minimum and maximum x and y parameters, define a bounding box that will be used to filter the input features. Only features that intersect with the bounding box are returned.
If all four coordinates of the search envelope are specified as 0, the search envelope will be disabled.
Clip to Search Envelope
When selected, this parameter removes any portions of imported features being read that are outside the Search Envelope.
The example below illustrates the results of the Search Envelope when Clip to Search Envelope is not selected (set to No) and when it is selected (set to Yes).
- No: Any features that cross the search envelope boundary will be read, including the portion that lies outside of the boundary.
- Yes: Any features that cross the search envelope boundary will be clipped at the boundary, and only the portion that lies inside the boundary will be read. The underlying function for the Clip to Search Envelope function is an intersection; however, when Clip to Search Envelope is selected, a clipping operation is also performed in addition to the intersection.
Advanced
Preserve Original Null Value For Z
Specifies whether or not to preserve the null value placeholder for z coordinates defined by the %H9 header tag. If Yes, the z coordinate of the geometry will be unchanged; if No, it will be set to 0.
For example, if the %H9 tag is set to -99.00 and, while reading a feature, it encounters a z coordinate of -99.00, then based on the value of this parameter, either the z coordinate will remain as -99.00 (if Yes) or changed to 0.0 (if No).
Edge tolerance for generalizing splines
After the reader has converted splines to straight lines, use this parameter to remove extraneous points. Real values from 0 and higher are acceptable. If a negative number is input, the DSFL reader will ignore it, and not generalize the line. This parameter is valid only if Points Per Segment is at least 1.
This parameter functions similar to a Generalizer transformer using the Douglas algorithm.
A recommended use is to set Points Per Segment to a moderately high number, such as 100, and then generalize to an acceptable precision. This will keep the overall number of points generated down, but will ensure precision is available where it is needed to keep the error down.
Use Comma as a Delimiter
If Yes, this directive tells the reader to also use the comma (,) as a delimiter when separating DSFL tokens as well as when parsing attributes. This setting removes commas from attributes (for example, “Vancouver, Canada” becomes “Vancouver Canada”). If No, the reader keeps the commas in the attributes.
Note that if the DSFL file’s tokens or coordinate points are separated with commas, the reader may not work properly. However, since FME only supports the basic version of DSFL (and commas are not allowed to separate tokens and coordinates in the basic version), this should never be a problem.