Global Mapper Pro

Elevation mosaic does not feather properly upon export

Discovery Global Mapper User

Hi All,

I am attempting to blend 2 elevation datasets (XML format) using seamlines and feathering but the output is not feathered properly, unlike what is shown in the workspace. These are my choices for blending and output:

- lower resolution data as the base layer

- higher resolution data is middle layer. It uses the valid data extent polys for inside feathering (25m). Water is set to NoData.

- lower resolution data as the upper. It uses the valid data extent polys of the high resolution data for outside feathering (25m).

- Exported to gridfloat

- tested on Global Mapper 16 and 17.2.

This arrangement appears to work nicely as visible in the workspace. The elevation data is smoothed out and the elevation values reported during mouse-over look ok. Unfortunately, the exported version has "pits" along the feather polygons. These pits appear to range from -9999 up to the valid value.

Does anyone know how to avoid this?   The attached image shows the process.

side note: Some of the minor polygons in the example aren't being honored as feathering seeds for the upper layer, but that is easily fixed by making the polys larger. There must be a size threshold in place.


  • bmg_bob
    bmg_bob Global Mapper Programmer

    I suggest that you download the latest version of Global Mapper 17 to see if this problem has been fixed.  If the problem persists, please send a detailed description of your workflow and the results, along with sample data that will reproduce the problem to Blue Marble Geographics Support (  This will ensure that the support team sees the problem and provide a timely response.


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