Global Mapper v24.0

Image that Crosses International Dateline - mirrored - stretched

maxsquires Global Mapper User
edited July 2008 in Projection Questions

I am wondering if there is a problem with the reading of data that crosses the international dateline.

I am working with a Mercator projected raster image (I can supply it to you via email, but it can also be found by the following method)


Office of Coast Survey - NOAA Raster Navigational Charts

agree to the statements by pressing the "Proceed to NOAA RNC? (BSB) Downloads" button.

press the ~"textual" button

on the following screen select the dropdown toggle that allows you to display more charts on the page.

select "1019"

select the check box next to it
scroll up to top of page and press the "Review Selections>>" button.

on the following screen press the "Order Selections" button.

wait a few moments,

then download the file

The kap file 513.kap, when added to the map dispaly is drawn stretched out to both extents of the map and mirror-imaged.

There are a couple of NOAA Charts that span the dateline in this way and I would love to be able to work with them.

Thanks for your help.



  • global_mapper
    global_mapper Administrator
    edited July 2008

    The problem was that the Mercator projection defined in the chart didnt' specify a central meridian, so 0 was used, which of course does not cross the ATM, hence the strange display of the chart. I have now updated Global Mapper to detect this situation and use a projection with a central meridian at the ATM, which fixes the problem.

    I have placed a new build at with the change for you to try. Simply download that file and extract the contents into your existing v9.xx installation folder to give it a try.

    Let me know if I can be of further assistance.


    Global Mapper Support
Sign In or Register to comment.