Global Mapper Pro Coming Soon

Steps for Extracting from a DEM Elevation Data from Point Grid within an Irregular Polygon ?

Hi,

 I working on a geomorphic analysis the landforms of a part of Louisiana using Global Mapper 17 and the lidar DEMs from the Louisiana Atlas website. 

 What are the precise steps that can be used to create a point grid with regular rows and columns for an entire irregular polygon, which enclose a landform of interest and extract elevation grids from these point grids? I would like to do something similar to what what was done with slope, except with elevation, in the May 1, 2016 Blue Marble video, “Analyzing Terrain in Global Mapper,” starting at 1:02:00

I intend to use this elevation data for statistical analyzes, such as a frequency plot and calculation of the median value and interquartile range of elevations for each polygon. Can Global Mapper do such analyses? If not, what software is compatiable with data exported from Global Mapper?

An example of the type of analyses that the data will be used for is illustrated by: 

Hassenruck-Gudipati, H.J., Ellis, T.S., Goudge, T.A. and Mohrig, D., 2021. A multi-proxy assessment of terrace formation in the lower Trinity River valley, Texas. Earth Surface Dynamics Discussions, pp.1-22.

An example of one of the irregular polygons that I am interested in extracting gridded elevation data from is selected in the below screen save from Global Mapper 17.


Any help that can be given would greatly appreciated.

Answers

  • MicheleMichele Posts: 61
    Hi,
    Maybe the simplest way is:
    with the cropping shape selected, create a grid. In the grid options choose to create only points at the intersections. Also choose to create the grid only inside the selected area.
    Now you will have points equally spaced over the elevation grid.
    Select the points and calculate slopes and elevation attributes from the elevation grid.
    Now you can export the points to csv and continue with any calculations you want to do in excel or keep working on the attributes in GM.
    Best regards
  • It is stated above:

    "with the cropping shape selected, create a grid. In the grid options choose to create only points at the intersections."

    How does a person specifically carry out these operations, in terms of the specific buttons and menu bars used? I have tried to follow these instructions numerous times using different combinations of what seem to be the appropriate buttons and menu items and gotten absolutely nowhere.

    Is there an Youtube or other video that explains or shows this process in detail such that person can see the specific menus and buttons used and in what sequence?
Sign In or Register to comment.