Contour Lines

global_noobieglobal_noobie Global Mapper UserPosts: 15Trusted User
edited April 2014 in Elevation Data
I just downloaded the "os terrain 50" data of the UK from ordanace, it came in two types.

[ESRI ® Shape (Contours): 1.1 Gb]
&
[ASCII Grid and GML (Grid): 162 Mb]

If I converted the contour data to ascii grid, would this offer me a potentially better quality data the equiv of better resolution or not?

I think not, but someone on a more generalist forum said it would so I was hoping to get a fianl answer here.

One last thing, the grid data I downloaded from above seems to have a slightly disjointed look about it.
Is this because of how they did it, something I have not set in GM, or can this be rectified by using the contour data and converting it?

I also provided that sample data in the picture just in case it was required.
Free large file exchange service without size limits (134kb)
425hty807

Thanks.

Comments

  • global_noobieglobal_noobie Global Mapper User Posts: 15Trusted User
    edited April 2014
    The picture is here...
    View image: seam
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2014
    You will lost some information going from a contour to a grid vs. getting the grid directly (assuming it wasn't generated from contours) as the contour lines don't have any information about the terrain between the contours, whereas the grid has everything. I would suggest downloading the ASCII Grid files and then batch converting them to Global Mapper Grid files to make them much smaller and faster to load.

    I would then create a map catalog (File->Create New Map Catalog) from all of the grid files. The seam that you are seeing is a visual effect caused by shadowing and interpolation not working across file boundaries unless the grid files are known "siblings", such as if they are all in a map catalog or tiles from an online layer. So using the map catalog should help with that, or exporting all of the data to a single large GMG file.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    geohelp@bluemarblegeo.com
    Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
  • global_noobieglobal_noobie Global Mapper User Posts: 15Trusted User
    edited April 2014
    Thanks admin, one day I hope to be able to post a question you don't know the answer to :)
  • 946946 Global Mapper User Posts: 132Trusted User
    edited April 2014
    I hope for that day also..
    the next issue that I ll have related to GM it will be in my native language! Noroc Mike !!
    ha ha
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2014
    Eu pot oferi sprijin în toate limbile.
Sign In or Register to comment.