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example_grits.md

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Automatic gridding and filtering of Multibeam data

First, we use the 'multibeam' fetches module as a datalist entry in a waffles command to fetch and grid the multibeam data in our region, then using that result as a datalist entry in a waffles command to grid the data using the 'IDW' waffles gridding module.

waffles -R-123.25/-123/48.25/48.5 -E .11111111s -O mb -p -P epsg:4326 -m -u -M stacks multibeam
waffles -R-123.25/-123/48.25/48.5 -E .11111111s -O mb_idw -p -P epsg:4326 -m -u -M IDW:radius=10 mb19_n48x50_w123x25_2024v1.tif

Figure 1. Auto-gridded raw multibeam data

The above results show some major artifacts from the raw multibeam data, so we then filter that output using the grits 'outlier' filter and re-generate the IDW grid with waffles:

grits mb19_n48x50_w123x25_2024v1_filtered.tif -M outliers
waffles $(dlim -r mb19_n48x50_w123x25_2024v1.tif) -M IDW:radius=5 -O mb_idw -E .11111111s -p -P epsg:4326 mb_data19_n_w_filtered.tif

Figure 2. Auto-grided filtered multibeam data

We can combine all the above steps using a single waffles command to fetch the multibeam, filter it using the grits 'outlier' module with the waffles -T switch and generate an IDW DEM with the waffles 'IDW' module.

waffles -R-123.25/-123/48.25/48.5 -E .11111111s -O mb -p -P epsg:4326 -m -u -M IDW:radius=10 -T outliers:stacks=True multibeam