Export of large raster file to XYZ grid takes extremely long

Jurgen

When exporting a large 32-bit raster to an XYZ grid file, the process takes an extremely long time—so long that the progress bar doesn’t even begin to move. In previous versions, the same export ran very quickly, even with very large rasters.

As a temporary workaround, I’ve been masking the raster using a coverage-area feature selected in the “Export Bounds” tab. Once the raster is fully masked, the XYZ export completes within seconds.

I also tested this with the latest build (GM 26.2, b111825), but the issue remains.

Is anyone else experiencing this? Could there be a setting I’m overlooking?

Thanks!

bmg_mike

What is the source of the data that you are exporting from? I just tried a local test from a large GMG grid and the XYZ grid export proceeded quickly.

The fact that exporting a masked area makes the process much faster makes me think that perhaps your initial export bounds are much larger than you are expecting. Are you perhaps exporting from an online terrain source, or maybe some other loaded data is making the default bounds much larger?

If this doesn't help, providing your errlog.txt file (see Config -> General -> Advanced dialog for location) should log the basics of the export so I could see if there are any obvious issues there.

Thanks,

Mike

Global Mapper Guru

Jurgen

Hi Mike,

I am using a local geotiff raster for the export to XYZ.

errlog.txt

no use of masked area: (this would take more than 10 hours to export)

2025-11-19_110938.jpg

[19/11/2025 10:59:54] [STATUS] Elevation XYZ Grid Export Starting to <D:\test1.xyz>, Size: 13409x28871, Bounds: (107889.630, 146927.260) - (114593.630, 161362.260)

with the use of masked area: (export within 1 minute)

[19/11/2025 11:10:22] [STATUS] Elevation XYZ Grid Export Starting to <D:\test2.xyz>, Size: 12276x21988, Bounds: (107889.630, 146927.260) - (114027.130, 157920.760)

Jurgen

here's the a visual of the 2 bounds:

bmg_mike

The sizes and bounds look reasonably close, so I don't think that's the issue.

What options are you using when performing the export? Specifically, if the Interpolate Gaps option is set and the data is mostly no-data, I could see a cropped export being faster.

Is it possible for you to provide the data that is causing the issue?

Thanks,

Mike

Global Mapper Guru

Jurgen

Hi Mike,

The issue I’m encountering appears to be a bug. Tech Support has already assigned a bug ticket to it.

Thanks for your help.

Jürgen

bmg_mike

Hi Jürgen,

I have taken a look and found the issue. You need to check the option to 'Export Values in Row-Major Order' and the process will be dramatically faster. The default of column major is incredibly inefficient for this particular data set as it's too large to cache everything in memory so it thrashes through the entire file for each column.

I'm changing the default to Row-Major which matches pretty much every other format and making the setting be remembered between runs.

Thanks,

Mike

Global Mapper Guru

Jurgen

Hi Mike,

That's very good news, thanks so much for your help!

I also found a workaround by creating a point cloud and exporting this layer to an XYZ.

Thanks,

Jürgen