Global Mapper Pro

Create Perpendicular Lines Along Selected Line - Further Options

KurtM
KurtM Water Resources EngineerTrusted User
edited February 2013 in Suggestion Box
I was excited to see the addition of the new tools Create Skeleton and Create Perpendicular Lines along a Line tools during yesterday’s webinar.

I envision myself using these tools as follows.
  1. Create an area by tracing a river boundary from a raster image.
  2. Create a skeleton along the river – this will be the river CL
  3. Create perpendicular lines along the CL to be stationing markers.
  4. Use measure tool to measure from a surveyed cross section to the nearest perpendicular line (station marker) in order to determine stationing of the surveyed cross section

In the example below, I used the Perpendicular Lines tool three times to create Major (100 m spacing at 30 m width), Intermediate (50 m spacing at 15 m width), and Minor (10 m spacing at 5 m width). This worked out well, but I ended up with overlapping lines at the intermediate and major lines. It would be great to see the tool expanded so that all the options are available in one menu as follows:
  • Specify Major perpendicular line spacing, and line width
  • Specify Intermediate perpendicular line spacing, and line width
  • Specify Minor perpendicular line spacing, and line width
  • Create additional perpendicular line at all line intersections along said line (yes / no check box)

This combination of options would allow for the creation of an alignment and would assign stationing to points along the alignment without having to use the measure tool.

Ultimately, I’d be very excited to be able to load a group of surveyed points, and have GlobalMapper assign a station and offset to each point – that would be so cool!

Thanks for the webinar,
Kurt

Comments

  • global_mapper
    global_mapper Administrator
    edited February 2013
    Kurt,

    That is a nice image. I have added a todo item (#11470) for adding support for multiple line lengths/styles for the perpendicular lines.

    The last option to create an additional perpendicular line I didn't understand though. What purpose would it serve? Wouldn't you just have overlapped lines if you did that?

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.bluemarblegeo.com/
  • KurtM
    KurtM Water Resources Engineer Trusted User
    edited February 2013
    Hey Mike,

    Thanks for the quick reply. Maybe I should go into a little more detail about my application (see revised image). The dark blue lines are cross sections that I surveyed in the field. I now need to associate each cross section with station for input into a hydraulic model (HEC-RAS, or River 1D for example). For the bottom cross section (JF0500W-actual), I can see that it's between Sta 2600 and 2700, but I'm not exactly sure where. So, I can use the measure tool and subtract the distance from 2700, or add the distance from 2600. This is okay for only a few cross sections. If you’re surveyed cross section is at a point where the CL is quite curved, it’s more tedious to measure along a curved line, than a straight line. In the end if you’re off a little bit, it’s no big deal, but it’s nice to be as accurate as possible.

    If GM could create a line perpendicular to the River CL at intersection of the river CL and JF0500W-actual, I could simply read it's title to determine the sta of JF0500w-actual without using the measure command. So the software would have to look for intersections along the line, and create additional perpendicular lines at said intersection.

    If my surveyed cross section was perfectly square to the river CL, you're right, I would have overlapping lines. However, they're always skewed a little bit – off by a few degrees. In which case, I would have three lines intersecting at one point: the river CL, the original surveyed cross section, and the newly created perpendicular line, which is almost parallel to the surveyed cross section, but not quite.

    Thanks for adding my suggest as a To-Do.

    Kurt



    GM-screen1.png
  • global_mapper
    global_mapper Administrator
    edited February 2013
    Kurt,

    Thanks for the explanation, I understand the utility of the extra perpendicular line now. I'll add that to the todo item as well.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.bluemarblegeo.com/
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