DXFtoLFH

1. When importing a set of splines, the program brings in the control points for the curves rather than the actual curves. The DXFtoLFH converter is only concerned with line, polyline and arc entities to describe the sections of a ship or yacht. Spline entities are not dealt with as such, and only their control points are imported. A workaround consists in saving a file containing spline entities as an Autocad version 12 DXF. This can be done, for example, via Autocad and Rhinoceros.

2. When importing a set of sections, some are brought in as longitudinals. When importing a DXF file, the DXFtoLFH converter will identify a line, polyline or arc entity as a section if the following conditions hold:

• the largest variance on X (max-min) is within a user-defined tolerance, normally 1mm, AND
• section points have a non-negative Y value.

If any negative Y points exist, these can be removed via Tools, Delete Negative Y Points. See also FAQ 3. below.

3. How does the ‘Largest Variance on X’ parameter work? The ‘Largest Variance on X (max-min)’ is used for setting the maximum variance in the longitudinal or X direction (post mapping) of a line. If the maximum minus the minimum value of X is less than or equal to the value it will be set as a section to output in the LFH file. This is useful if there is a slight variance in the X-values set in the DXF file.

4. If there is a variance in the X-values of a DXF section, what is the longitudinal position, or ‘X-position’ of the section output in the LFH file? The X-position of the first point defined on the line.

5. When should I use the ‘Guess Mapping’ option of the Map Curves dialog? The option guesses the best mapping function for the entire set of curves, based on their X, Y and Z variances. This functionality can be used after importing a set of DXF lines, if the coordinate system does not appear to be correct. Also, it should be used after geometry clean-ups, such as Tools, Remove Short Intervals to refresh the lines and the list of curves in the main window.