Novapoint Landscape Library

Converting a 2D arc element into a 3D polyline requires the arc element to be replaced by a series of straight lines. This adds more break points and the resultant line follows the original arc relatively well.

• The dialog box 'TenTable - Lines Only' will pop up with the button 'Lines Only' of the dialog box 'Create 3D - Line'. The settings to convert the selected 2D entity (lines/arcs/circles/transition curves/polyline) to a series of straight-lines (2D) are to be defined in this dialog box.
  

  

The length of the straight-lines resulting from the conversion to straight lines is controlled with this option.

• Define the length (meter) of each elemental straight-line.

• If the value is 5.0m, which is the default value, none of the resulting straight-lines will be longer than 5.0m.

• This does not mean that all the lines are 5.0m long, but none of the lines will be longer than 5.0m.

There is no rule so that an appropriate value can be used, 5.0m is perhaps sufficient for long lines.

• However, 5.0m is too small for sub-division of edge lines, traffic islands, traffic intersections, etc. 0.5m is perhaps a better value in these cases.

Degree of accuracy determines the number of elemental straight-lines, the selected 2D entity to be sub-divided.

• The function suggests a default value of 1.00.

• If this value is increased, accuracy is increased and arcs are subdivided into more straight-lines.

• Smaller values give fewer lines.

• Large arcs require greater accuracy than small arcs.

• Degree of accuracy must therefore be evaluated from case to case.

• Any value from 0.1 to 3.0 can be used.

In most cases, an accuracy of 1.00 is more than sufficient.

I *f an accuracy of 1.00 does not give sufficient detail, a higher accuracy level can be specified.

• An accuracy of 2.00 subdivides arcs and transition curves into twice as many straight-lines as an accuracy of 1.00.
  • 0.1 Very low accuracy.
  • 3.0 Very high accuracy.
  • 0.5 Half accuracy.
  • 2.0 Double accuracy.

If a circle in plan with a radius of 10.0m is converted to straight-lines.

Accuracy 1.0 Maximum deviation between radius and line segment: 3.1 mm, segment length 0.499m.

Accuracy 2.0 Maximum deviation between radius and line segment: 0.78 mm, segment length 0.249m.

Accuracy 0.5 Maximum deviation between radius and line segment: 12.4 mm, segment length 0.997m.

See the below illustration where deviation and segment length are graphically represented. The parameter 0,0031m is deviation and 0,4986m is segment length.