Global Mapper v25.0

Create rectangle based on centre coordinate and W x H?

BillB
BillB Global Mapper UserTrusted User
edited August 2013 in Technical Support
Hi, we quite often know where the centre of our site is and then want to define a study area (rectangle) that we know will fit on a sheet later, so maybe 15x12km.

Is there any current way to create a rectangle like this?

Thanks

Bill

Comments

  • global_mapper
    global_mapper Administrator
    edited August 2013
    Bill,

    Yes, you can right-click in the Digitizer Tool and under the Create Areas Features submenu select to create a rectangle/square by specifying coordinates. You can specify a corner and width and height there.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • BillB
    BillB Global Mapper User Trusted User
    edited August 2013
    Hi Mike, thanks for the response. Sorry to be picky, but specifying a corner + width x height is not quite the same thing. I know where the centre of my site is. I'm trying to avoid calculating corner coordinates by being able to define width and height relative to the centre. Rather like the Range Ring function: click a point (or enter exact coordinates) then enter width and height to create a rectangle aligned to the current coordinate system.

    Thanks, Bill
  • kentman
    kentman Global Mapper User Trusted User
    edited August 2013
    Hi Bill,

    There is a way to do this by a grid 1 column by 1 row at a specified height and width: Select the digitize tool > select the create regular grid button and then click anywhere (or specifically the center of your site) and fill in the details:

    Attachment not found.

    If you want to input coordinates, click the 'Anchor point' button and enter your site coordinates and you with produce your rectangle at the size you want at in the position you require.

    Attachment not found.

    Hope that helps,

    Kent
  • BillB
    BillB Global Mapper User Trusted User
    edited August 2013
    Hi Kent, thanks for your suggestions - couldn't read the attachments but get the description, thank you. Unless I am misunderstanding, creating a grid doesn't quite do the job, because the grid is created below right of the anchor point. There is no option for the anchor point to be at the centre of the grid. However, if I make a 2 row x 2 col grid of the the required overall size, I can then move it, using the middle of the grid (like cross-hairs) onto my site centre. I can then snap a rectangle onto the outer corners of the grid. Not perfect, but a good start.

    I'm really looking for something more like the range-ring function. Maybe the grid dialog could have an option "Anchor point at centre of grid"?

    Cheers

    Bill
  • BillB
    BillB Global Mapper User Trusted User
    Thought I had found an answer to this with the Range Ring option "Create bounding rectangle instead of rings" but it appears to create the rectangle on the lat-long axes rather than the local grid. Any way to create the "range-ring" rectangle aligned ot the local grid?
  • Ice Age Mark
    Ice Age Mark Global Mapper User Trusted User
    Bill,

    It looks like the rotation isn't working when a rectangle is created instead of an ellipse. If this were fixed, it should do what you want by specifying the rotation of your grid.

    Regards,

    Mark
  • BillB
    BillB Global Mapper User Trusted User
    edited July 2015
    Thanks Mark

    I tried it again with both elipse and rectangle and they definitely align to lat-long grid, not local grid.

    GM/BM people, could there be an option in the Range Ring dialog to align with Local Grid? It obviously didn't matter where "0" was when we were only creating circles for range rings, but now we have elipses and rectangles, it certainly does matter.

    Bill
  • bmg_bob
    bmg_bob Global Mapper Programmer
    Hi Bill,

    I have added item #16042 to our task list requesting an option to align rectangular range rings with the local grid.

    Cheers,

    Bob
  • BillB
    BillB Global Mapper User Trusted User
    So how long will it take to get through the other 16,041 tasks?
    Or have you already started?
    ;-)
  • Ice Age Mark
    Ice Age Mark Global Mapper User Trusted User
    Hello there bmg_bob,

    Just following up here to see if this ticket includes the bug issue that the rotation function works for an ellipse, but not for a rectangle when that box is checked; or if a separate one needs to be made?

    Thanks and regards,

    Mark
  • kbellis
    kbellis Global Mapper User Trusted User
    Hello BillB - Great idea! Thank you for suggesting this!! Sorry it took me 5 years to comment !


    Hello Mark,

    RE: v19.1, the request that BillB had initially made, and the bug report that you mentioned above, apparently haven't been addressed yet. Not being privy to the cited bug's details of three years ago, the bug that I'm seeing in v19.1 (b080618) is a bit nuanced.

    I had originally gone looking through the forum postings for any ideas to help me create a GSD and Overlap script that would facilitate, as a starting point, rectangular area creation predicated a few variables including; i.e., PrinciplePointPosition (GPSLongitude, GPSLatitude, and RelativeAltitude); GimbalYawDegree; and a few givens; i.e., image dimensions in pixels (imageX, imageY), crop factor, focal length in mm, and CCD sensor size CCDx and CCDy in mm.

    The rectangular range rings rotation angle are not being applied correctly; 1.) the rectangle isn't rotating when the rotation values are changed; 2.) the slight rotation that all rectangles do share in the example above is due to the influence of the projection (UTM, in this case) as when in geographic projection, they are clearly showing the axis on cardinal points; 3) and probably the most curious, the rotation angle is somehow screwing up the axis dimensions.

    The idea for GSD and Overlap areas are actually byproducts. The initial idea arises after talking with a forester friend who was a bit disappointed that that he couldn't properly place his forest photos in scale on an averaged projected plane and in correct rotation. So the Overlap script would then have a variant added to it; with the placement of the actual image rotated and scaled into the Global Mapper workspace.

    Lastly, we'll need to lobby the developers for a new export type: multi-layered .psd (Photoshop Document) which would then facilitate masks, blending treatments, and other editing techniques in PS to deal with seams and the always radical changes in perspective from image to image. For example:


    Kind regards,

    Kelly


  • kbellis
    kbellis Global Mapper User Trusted User
    edited August 2018
    I'm not sure how long the ring ellipses/ bounding rectangles issues have been present, probably since before v20; however, it's worth discussing them this morning - better late than never.

    1) Even though the general Measure/Units settings are related to all things being on grid, the ellipses and their associated bounding rectangles are not.

    2) The bounding rectangles' axis are not paralleling the ellipses; instead and undesirably, remain parallel with the meridian.